From 53c29e9261cce3b8401a74823b571b6a32e065e8 Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Thu, 12 Sep 2024 18:40:21 +0200
Subject: [PATCH 01/26] Introduce lowercase-string

---
 src/PhpDoc/TypeNodeResolver.php               |  11 +-
 src/Type/Accessory/AccessoryArrayListType.php |   5 +
 .../Accessory/AccessoryLiteralStringType.php  |   5 +
 .../AccessoryLowercaseStringType.php          | 378 ++++++++++++++++++
 .../Accessory/AccessoryNonEmptyStringType.php |   5 +
 .../Accessory/AccessoryNonFalsyStringType.php |   5 +
 .../Accessory/AccessoryNumericStringType.php  |   5 +
 src/Type/Accessory/HasOffsetType.php          |   5 +
 src/Type/Accessory/HasOffsetValueType.php     |   5 +
 src/Type/Accessory/NonEmptyArrayType.php      |   5 +
 src/Type/Accessory/OversizedArrayType.php     |   5 +
 src/Type/ArrayType.php                        |   5 +
 src/Type/CallableType.php                     |   5 +
 src/Type/ClassStringType.php                  |   5 +
 src/Type/ClosureType.php                      |   5 +
 src/Type/Constant/ConstantStringType.php      |   5 +
 src/Type/FloatType.php                        |   5 +
 src/Type/IntersectionType.php                 |   5 +
 src/Type/IterableType.php                     |   5 +
 src/Type/JustNullableTypeTrait.php            |   5 +
 src/Type/MixedType.php                        |  17 +
 src/Type/NeverType.php                        |   5 +
 src/Type/NullType.php                         |   5 +
 src/Type/ObjectType.php                       |   5 +
 src/Type/StaticType.php                       |   5 +
 src/Type/StrictMixedType.php                  |   5 +
 src/Type/StringType.php                       |   5 +
 src/Type/Traits/LateResolvableTypeTrait.php   |   5 +
 src/Type/Traits/ObjectTypeTrait.php           |   5 +
 src/Type/Type.php                             |   2 +
 src/Type/UnionType.php                        |   5 +
 src/Type/VoidType.php                         |   5 +
 32 files changed, 547 insertions(+), 1 deletion(-)
 create mode 100644 src/Type/Accessory/AccessoryLowercaseStringType.php

diff --git a/src/PhpDoc/TypeNodeResolver.php b/src/PhpDoc/TypeNodeResolver.php
index c0fa6c5585..06098d7938 100644
--- a/src/PhpDoc/TypeNodeResolver.php
+++ b/src/PhpDoc/TypeNodeResolver.php
@@ -46,6 +46,7 @@
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\Accessory\AccessoryArrayListType;
 use PHPStan\Type\Accessory\AccessoryLiteralStringType;
+use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
 use PHPStan\Type\Accessory\AccessoryNonFalsyStringType;
 use PHPStan\Type\Accessory\AccessoryNumericStringType;
@@ -216,9 +217,11 @@ private function resolveIdentifierTypeNode(IdentifierTypeNode $typeNode, NameSco
 				]);
 
 			case 'string':
-			case 'lowercase-string':
 				return new StringType();
 
+			case 'lowercase-string':
+				return new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]);
+
 			case 'literal-string':
 				return new IntersectionType([new StringType(), new AccessoryLiteralStringType()]);
 
@@ -287,10 +290,16 @@ private function resolveIdentifierTypeNode(IdentifierTypeNode $typeNode, NameSco
 				]);
 
 			case 'non-empty-string':
+				return new IntersectionType([
+					new StringType(),
+					new AccessoryNonEmptyStringType(),
+				]);
+
 			case 'non-empty-lowercase-string':
 				return new IntersectionType([
 					new StringType(),
 					new AccessoryNonEmptyStringType(),
+					new AccessoryLowercaseStringType(),
 				]);
 
 			case 'truthy-string':
diff --git a/src/Type/Accessory/AccessoryArrayListType.php b/src/Type/Accessory/AccessoryArrayListType.php
index 511087818d..d32cc8882c 100644
--- a/src/Type/Accessory/AccessoryArrayListType.php
+++ b/src/Type/Accessory/AccessoryArrayListType.php
@@ -387,6 +387,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createNo();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createNo();
diff --git a/src/Type/Accessory/AccessoryLiteralStringType.php b/src/Type/Accessory/AccessoryLiteralStringType.php
index dd4af579ac..110fbea58c 100644
--- a/src/Type/Accessory/AccessoryLiteralStringType.php
+++ b/src/Type/Accessory/AccessoryLiteralStringType.php
@@ -297,6 +297,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createYes();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createMaybe();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createMaybe();
diff --git a/src/Type/Accessory/AccessoryLowercaseStringType.php b/src/Type/Accessory/AccessoryLowercaseStringType.php
new file mode 100644
index 0000000000..0e66c5d021
--- /dev/null
+++ b/src/Type/Accessory/AccessoryLowercaseStringType.php
@@ -0,0 +1,378 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Type\Accessory;
+
+use PHPStan\Php\PhpVersion;
+use PHPStan\PhpDocParser\Ast\Type\IdentifierTypeNode;
+use PHPStan\PhpDocParser\Ast\Type\TypeNode;
+use PHPStan\TrinaryLogic;
+use PHPStan\Type\AcceptsResult;
+use PHPStan\Type\BenevolentUnionType;
+use PHPStan\Type\BooleanType;
+use PHPStan\Type\CompoundType;
+use PHPStan\Type\Constant\ConstantArrayType;
+use PHPStan\Type\Constant\ConstantIntegerType;
+use PHPStan\Type\ErrorType;
+use PHPStan\Type\FloatType;
+use PHPStan\Type\GeneralizePrecision;
+use PHPStan\Type\IntegerType;
+use PHPStan\Type\IntersectionType;
+use PHPStan\Type\MixedType;
+use PHPStan\Type\ObjectWithoutClassType;
+use PHPStan\Type\StringType;
+use PHPStan\Type\Traits\MaybeCallableTypeTrait;
+use PHPStan\Type\Traits\NonArrayTypeTrait;
+use PHPStan\Type\Traits\NonGenericTypeTrait;
+use PHPStan\Type\Traits\NonIterableTypeTrait;
+use PHPStan\Type\Traits\NonObjectTypeTrait;
+use PHPStan\Type\Traits\NonRemoveableTypeTrait;
+use PHPStan\Type\Traits\UndecidedComparisonCompoundTypeTrait;
+use PHPStan\Type\Type;
+use PHPStan\Type\UnionType;
+use PHPStan\Type\VerbosityLevel;
+
+class AccessoryLowercaseStringType implements CompoundType, AccessoryType
+{
+
+	use MaybeCallableTypeTrait;
+	use NonArrayTypeTrait;
+	use NonObjectTypeTrait;
+	use NonIterableTypeTrait;
+	use UndecidedComparisonCompoundTypeTrait;
+	use NonGenericTypeTrait;
+	use NonRemoveableTypeTrait;
+
+	/** @api */
+	public function __construct()
+	{
+	}
+
+	public function getReferencedClasses(): array
+	{
+		return [];
+	}
+
+	public function getObjectClassNames(): array
+	{
+		return [];
+	}
+
+	public function getObjectClassReflections(): array
+	{
+		return [];
+	}
+
+	public function getConstantStrings(): array
+	{
+		return [];
+	}
+
+	public function accepts(Type $type, bool $strictTypes): TrinaryLogic
+	{
+		return $this->acceptsWithReason($type, $strictTypes)->result;
+	}
+
+	public function acceptsWithReason(Type $type, bool $strictTypes): AcceptsResult
+	{
+		if ($type instanceof MixedType) {
+			return AcceptsResult::createNo();
+		}
+		if ($type instanceof CompoundType) {
+			return $type->isAcceptedWithReasonBy($this, $strictTypes);
+		}
+
+		return new AcceptsResult($type->isLiteralString(), []);
+	}
+
+	public function isSuperTypeOf(Type $type): TrinaryLogic
+	{
+		if ($type instanceof CompoundType) {
+			return $type->isSubTypeOf($this);
+		}
+
+		if ($this->equals($type)) {
+			return TrinaryLogic::createYes();
+		}
+
+		return $type->isLiteralString();
+	}
+
+	public function isSubTypeOf(Type $otherType): TrinaryLogic
+	{
+		if ($otherType instanceof UnionType || $otherType instanceof IntersectionType) {
+			return $otherType->isSuperTypeOf($this);
+		}
+
+		return $otherType->isLiteralString()
+			->and($otherType instanceof self ? TrinaryLogic::createYes() : TrinaryLogic::createMaybe());
+	}
+
+	public function isAcceptedBy(Type $acceptingType, bool $strictTypes): TrinaryLogic
+	{
+		return $this->isAcceptedWithReasonBy($acceptingType, $strictTypes)->result;
+	}
+
+	public function isAcceptedWithReasonBy(Type $acceptingType, bool $strictTypes): AcceptsResult
+	{
+		return new AcceptsResult($this->isSubTypeOf($acceptingType), []);
+	}
+
+	public function equals(Type $type): bool
+	{
+		return $type instanceof self;
+	}
+
+	public function describe(VerbosityLevel $level): string
+	{
+		return 'lowercase-string';
+	}
+
+	public function isOffsetAccessible(): TrinaryLogic
+	{
+		return TrinaryLogic::createYes();
+	}
+
+	public function isOffsetAccessLegal(): TrinaryLogic
+	{
+		return TrinaryLogic::createYes();
+	}
+
+	public function hasOffsetValueType(Type $offsetType): TrinaryLogic
+	{
+		return $offsetType->isInteger()->and(TrinaryLogic::createMaybe());
+	}
+
+	public function getOffsetValueType(Type $offsetType): Type
+	{
+		if ($this->hasOffsetValueType($offsetType)->no()) {
+			return new ErrorType();
+		}
+
+		return new StringType();
+	}
+
+	public function setOffsetValueType(?Type $offsetType, Type $valueType, bool $unionValues = true): Type
+	{
+		$stringOffset = (new StringType())->setOffsetValueType($offsetType, $valueType, $unionValues);
+
+		if ($stringOffset instanceof ErrorType) {
+			return $stringOffset;
+		}
+
+		if ($valueType->isLowercaseString()->yes()) {
+			return $this;
+		}
+
+		return new StringType();
+	}
+
+	public function setExistingOffsetValueType(Type $offsetType, Type $valueType): Type
+	{
+		return $this;
+	}
+
+	public function unsetOffset(Type $offsetType): Type
+	{
+		return new ErrorType();
+	}
+
+	public function toNumber(): Type
+	{
+		return new ErrorType();
+	}
+
+	public function toAbsoluteNumber(): Type
+	{
+		return new ErrorType();
+	}
+
+	public function toInteger(): Type
+	{
+		return new IntegerType();
+	}
+
+	public function toFloat(): Type
+	{
+		return new FloatType();
+	}
+
+	public function toString(): Type
+	{
+		return $this;
+	}
+
+	public function toBoolean(): BooleanType
+	{
+		return new BooleanType();
+	}
+
+	public function toArray(): Type
+	{
+		return new ConstantArrayType(
+			[new ConstantIntegerType(0)],
+			[$this],
+			[1],
+			[],
+			TrinaryLogic::createYes(),
+		);
+	}
+
+	public function toArrayKey(): Type
+	{
+		return $this;
+	}
+
+	public function isNull(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
+	public function isConstantValue(): TrinaryLogic
+	{
+		return TrinaryLogic::createMaybe();
+	}
+
+	public function isConstantScalarValue(): TrinaryLogic
+	{
+		return TrinaryLogic::createMaybe();
+	}
+
+	public function getConstantScalarTypes(): array
+	{
+		return [];
+	}
+
+	public function getConstantScalarValues(): array
+	{
+		return [];
+	}
+
+	public function isTrue(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
+	public function isFalse(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
+	public function isBoolean(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
+	public function isFloat(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
+	public function isInteger(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
+	public function isString(): TrinaryLogic
+	{
+		return TrinaryLogic::createYes();
+	}
+
+	public function isNumericString(): TrinaryLogic
+	{
+		return TrinaryLogic::createMaybe();
+	}
+
+	public function isNonEmptyString(): TrinaryLogic
+	{
+		return TrinaryLogic::createMaybe();
+	}
+
+	public function isNonFalsyString(): TrinaryLogic
+	{
+		return TrinaryLogic::createMaybe();
+	}
+
+	public function isLiteralString(): TrinaryLogic
+	{
+		return TrinaryLogic::createMaybe();
+	}
+
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createYes();
+	}
+
+	public function isClassStringType(): TrinaryLogic
+	{
+		return TrinaryLogic::createMaybe();
+	}
+
+	public function getClassStringObjectType(): Type
+	{
+		return new ObjectWithoutClassType();
+	}
+
+	public function getObjectTypeOrClassStringObjectType(): Type
+	{
+		return new ObjectWithoutClassType();
+	}
+
+	public function hasMethod(string $methodName): TrinaryLogic
+	{
+		return TrinaryLogic::createMaybe();
+	}
+
+	public function isVoid(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
+	public function isScalar(): TrinaryLogic
+	{
+		return TrinaryLogic::createYes();
+	}
+
+	public function looseCompare(Type $type, PhpVersion $phpVersion): BooleanType
+	{
+		return new BooleanType();
+	}
+
+	public function traverse(callable $cb): Type
+	{
+		return $this;
+	}
+
+	public function traverseSimultaneously(Type $right, callable $cb): Type
+	{
+		return $this;
+	}
+
+	public function generalize(GeneralizePrecision $precision): Type
+	{
+		return new StringType();
+	}
+
+	public static function __set_state(array $properties): Type
+	{
+		return new self();
+	}
+
+	public function exponentiate(Type $exponent): Type
+	{
+		return new BenevolentUnionType([
+			new FloatType(),
+			new IntegerType(),
+		]);
+	}
+
+	public function getFiniteTypes(): array
+	{
+		return [];
+	}
+
+	public function toPhpDocNode(): TypeNode
+	{
+		return new IdentifierTypeNode('lowercase-string');
+	}
+
+}
diff --git a/src/Type/Accessory/AccessoryNonEmptyStringType.php b/src/Type/Accessory/AccessoryNonEmptyStringType.php
index 16566ee530..b911c21fbb 100644
--- a/src/Type/Accessory/AccessoryNonEmptyStringType.php
+++ b/src/Type/Accessory/AccessoryNonEmptyStringType.php
@@ -294,6 +294,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createMaybe();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createMaybe();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createMaybe();
diff --git a/src/Type/Accessory/AccessoryNonFalsyStringType.php b/src/Type/Accessory/AccessoryNonFalsyStringType.php
index dacccd3e31..5703420e9f 100644
--- a/src/Type/Accessory/AccessoryNonFalsyStringType.php
+++ b/src/Type/Accessory/AccessoryNonFalsyStringType.php
@@ -294,6 +294,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createMaybe();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createMaybe();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createMaybe();
diff --git a/src/Type/Accessory/AccessoryNumericStringType.php b/src/Type/Accessory/AccessoryNumericStringType.php
index 9d37625612..9cb274782d 100644
--- a/src/Type/Accessory/AccessoryNumericStringType.php
+++ b/src/Type/Accessory/AccessoryNumericStringType.php
@@ -296,6 +296,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createMaybe();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createMaybe();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createNo();
diff --git a/src/Type/Accessory/HasOffsetType.php b/src/Type/Accessory/HasOffsetType.php
index 5ed39d9797..2194a10cef 100644
--- a/src/Type/Accessory/HasOffsetType.php
+++ b/src/Type/Accessory/HasOffsetType.php
@@ -297,6 +297,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createMaybe();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createMaybe();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createMaybe();
diff --git a/src/Type/Accessory/HasOffsetValueType.php b/src/Type/Accessory/HasOffsetValueType.php
index ae1ef84f56..853645c91a 100644
--- a/src/Type/Accessory/HasOffsetValueType.php
+++ b/src/Type/Accessory/HasOffsetValueType.php
@@ -353,6 +353,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createMaybe();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createMaybe();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createMaybe();
diff --git a/src/Type/Accessory/NonEmptyArrayType.php b/src/Type/Accessory/NonEmptyArrayType.php
index 1f2abd69b6..293e1f111f 100644
--- a/src/Type/Accessory/NonEmptyArrayType.php
+++ b/src/Type/Accessory/NonEmptyArrayType.php
@@ -364,6 +364,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createNo();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createNo();
diff --git a/src/Type/Accessory/OversizedArrayType.php b/src/Type/Accessory/OversizedArrayType.php
index 2e9da3ae05..fa64240e89 100644
--- a/src/Type/Accessory/OversizedArrayType.php
+++ b/src/Type/Accessory/OversizedArrayType.php
@@ -360,6 +360,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createNo();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createNo();
diff --git a/src/Type/ArrayType.php b/src/Type/ArrayType.php
index d2eaf1bc24..4543e36b77 100644
--- a/src/Type/ArrayType.php
+++ b/src/Type/ArrayType.php
@@ -358,6 +358,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createNo();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createNo();
diff --git a/src/Type/CallableType.php b/src/Type/CallableType.php
index ce30d8983c..82b3645a27 100644
--- a/src/Type/CallableType.php
+++ b/src/Type/CallableType.php
@@ -591,6 +591,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createMaybe();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createMaybe();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createMaybe();
diff --git a/src/Type/ClassStringType.php b/src/Type/ClassStringType.php
index 802d17e162..eaca9d4572 100644
--- a/src/Type/ClassStringType.php
+++ b/src/Type/ClassStringType.php
@@ -69,6 +69,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createMaybe();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createMaybe();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createYes();
diff --git a/src/Type/ClosureType.php b/src/Type/ClosureType.php
index 967b850525..e55847aae0 100644
--- a/src/Type/ClosureType.php
+++ b/src/Type/ClosureType.php
@@ -713,6 +713,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createNo();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createNo();
diff --git a/src/Type/Constant/ConstantStringType.php b/src/Type/Constant/ConstantStringType.php
index fcd467fbbb..4c42ce01d4 100644
--- a/src/Type/Constant/ConstantStringType.php
+++ b/src/Type/Constant/ConstantStringType.php
@@ -343,6 +343,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createYes();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createFromBoolean(strtolower($this->value) === $this->value);
+	}
+
 	public function hasOffsetValueType(Type $offsetType): TrinaryLogic
 	{
 		if ($offsetType->isInteger()->yes()) {
diff --git a/src/Type/FloatType.php b/src/Type/FloatType.php
index 2111d4d912..0ffa96e002 100644
--- a/src/Type/FloatType.php
+++ b/src/Type/FloatType.php
@@ -229,6 +229,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createNo();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createNo();
diff --git a/src/Type/IntersectionType.php b/src/Type/IntersectionType.php
index 8bf38bddda..7a81ed039c 100644
--- a/src/Type/IntersectionType.php
+++ b/src/Type/IntersectionType.php
@@ -637,6 +637,11 @@ public function isLiteralString(): TrinaryLogic
 		return $this->intersectResults(static fn (Type $type): TrinaryLogic => $type->isLiteralString());
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return $this->intersectResults(static fn (Type $type): TrinaryLogic => $type->isLowercaseString());
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return $this->intersectResults(static fn (Type $type): TrinaryLogic => $type->isClassStringType());
diff --git a/src/Type/IterableType.php b/src/Type/IterableType.php
index f36cab2e7f..6ef8ff5ee3 100644
--- a/src/Type/IterableType.php
+++ b/src/Type/IterableType.php
@@ -372,6 +372,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createNo();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createNo();
diff --git a/src/Type/JustNullableTypeTrait.php b/src/Type/JustNullableTypeTrait.php
index 294b7d1d2b..7f48131262 100644
--- a/src/Type/JustNullableTypeTrait.php
+++ b/src/Type/JustNullableTypeTrait.php
@@ -147,6 +147,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createNo();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createNo();
diff --git a/src/Type/MixedType.php b/src/Type/MixedType.php
index 865611056f..f72e8f3d76 100644
--- a/src/Type/MixedType.php
+++ b/src/Type/MixedType.php
@@ -21,6 +21,7 @@
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\Accessory\AccessoryArrayListType;
 use PHPStan\Type\Accessory\AccessoryLiteralStringType;
+use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
 use PHPStan\Type\Accessory\AccessoryNonFalsyStringType;
 use PHPStan\Type\Accessory\AccessoryNumericStringType;
@@ -916,6 +917,22 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createMaybe();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		if ($this->subtractedType !== null) {
+			$lowercaseString = TypeCombinator::intersect(
+				new StringType(),
+				new AccessoryLowercaseStringType(),
+			);
+
+			if ($this->subtractedType->isSuperTypeOf($lowercaseString)->yes()) {
+				return TrinaryLogic::createNo();
+			}
+		}
+
+		return TrinaryLogic::createMaybe();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		if ($this->subtractedType !== null) {
diff --git a/src/Type/NeverType.php b/src/Type/NeverType.php
index 5d488d319c..1523562cab 100644
--- a/src/Type/NeverType.php
+++ b/src/Type/NeverType.php
@@ -476,6 +476,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createNo();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createNo();
diff --git a/src/Type/NullType.php b/src/Type/NullType.php
index a59f86e868..ab50c2040e 100644
--- a/src/Type/NullType.php
+++ b/src/Type/NullType.php
@@ -295,6 +295,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createNo();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createNo();
diff --git a/src/Type/ObjectType.php b/src/Type/ObjectType.php
index 1732c3c627..b756e3f77d 100644
--- a/src/Type/ObjectType.php
+++ b/src/Type/ObjectType.php
@@ -1045,6 +1045,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createNo();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createNo();
diff --git a/src/Type/StaticType.php b/src/Type/StaticType.php
index bb55a6c9fa..e0d2924951 100644
--- a/src/Type/StaticType.php
+++ b/src/Type/StaticType.php
@@ -565,6 +565,11 @@ public function isLiteralString(): TrinaryLogic
 		return $this->getStaticObjectType()->isLiteralString();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return $this->getStaticObjectType()->isLowercaseString();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return $this->getStaticObjectType()->isClassStringType();
diff --git a/src/Type/StrictMixedType.php b/src/Type/StrictMixedType.php
index cc114d5c34..00a9141233 100644
--- a/src/Type/StrictMixedType.php
+++ b/src/Type/StrictMixedType.php
@@ -275,6 +275,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createNo();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createNo();
diff --git a/src/Type/StringType.php b/src/Type/StringType.php
index 5fe9ae444a..9fcd1e1895 100644
--- a/src/Type/StringType.php
+++ b/src/Type/StringType.php
@@ -240,6 +240,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createMaybe();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createMaybe();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createMaybe();
diff --git a/src/Type/Traits/LateResolvableTypeTrait.php b/src/Type/Traits/LateResolvableTypeTrait.php
index bff88f730e..fb03a4d170 100644
--- a/src/Type/Traits/LateResolvableTypeTrait.php
+++ b/src/Type/Traits/LateResolvableTypeTrait.php
@@ -452,6 +452,11 @@ public function isLiteralString(): TrinaryLogic
 		return $this->resolve()->isLiteralString();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return $this->resolve()->isLowercaseString();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return $this->resolve()->isClassStringType();
diff --git a/src/Type/Traits/ObjectTypeTrait.php b/src/Type/Traits/ObjectTypeTrait.php
index 0c37e439c7..8ca9c69c29 100644
--- a/src/Type/Traits/ObjectTypeTrait.php
+++ b/src/Type/Traits/ObjectTypeTrait.php
@@ -198,6 +198,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createNo();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createNo();
diff --git a/src/Type/Type.php b/src/Type/Type.php
index 727e2f8a31..398529994e 100644
--- a/src/Type/Type.php
+++ b/src/Type/Type.php
@@ -261,6 +261,8 @@ public function isNonFalsyString(): TrinaryLogic;
 
 	public function isLiteralString(): TrinaryLogic;
 
+	public function isLowercaseString(): TrinaryLogic;
+
 	public function isClassStringType(): TrinaryLogic;
 
 	public function isVoid(): TrinaryLogic;
diff --git a/src/Type/UnionType.php b/src/Type/UnionType.php
index af4ede1b40..08b8d2c186 100644
--- a/src/Type/UnionType.php
+++ b/src/Type/UnionType.php
@@ -612,6 +612,11 @@ public function isLiteralString(): TrinaryLogic
 		return $this->notBenevolentUnionResults(static fn (Type $type): TrinaryLogic => $type->isLiteralString());
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return $this->notBenevolentUnionResults(static fn (Type $type): TrinaryLogic => $type->isLowercaseString());
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return $this->notBenevolentUnionResults(static fn (Type $type): TrinaryLogic => $type->isClassStringType());
diff --git a/src/Type/VoidType.php b/src/Type/VoidType.php
index 8cbd1076ba..add4ffca45 100644
--- a/src/Type/VoidType.php
+++ b/src/Type/VoidType.php
@@ -207,6 +207,11 @@ public function isLiteralString(): TrinaryLogic
 		return TrinaryLogic::createNo();
 	}
 
+	public function isLowercaseString(): TrinaryLogic
+	{
+		return TrinaryLogic::createNo();
+	}
+
 	public function isClassStringType(): TrinaryLogic
 	{
 		return TrinaryLogic::createNo();

From 148ee3070affc9191720d57f39833fb2a4a9e6cf Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Fri, 13 Sep 2024 09:09:21 +0200
Subject: [PATCH 02/26] Update signature

---
 resources/functionMap.php | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/resources/functionMap.php b/resources/functionMap.php
index b79549a45d..80c57788d6 100644
--- a/resources/functionMap.php
+++ b/resources/functionMap.php
@@ -6361,7 +6361,7 @@
 'mb_strripos' => ['0|positive-int|false', 'haystack'=>'string', 'needle'=>'string', 'offset='=>'int', 'encoding='=>'string'],
 'mb_strrpos' => ['0|positive-int|false', 'haystack'=>'string', 'needle'=>'string', 'offset='=>'int', 'encoding='=>'string'],
 'mb_strstr' => ['string|false', 'haystack'=>'string', 'needle'=>'string', 'part='=>'bool', 'encoding='=>'string'],
-'mb_strtolower' => ['string', 'str'=>'string', 'encoding='=>'string'],
+'mb_strtolower' => ['lowercase-string', 'str'=>'string', 'encoding='=>'string'],
 'mb_strtoupper' => ['string', 'str'=>'string', 'encoding='=>'string'],
 'mb_strwidth' => ['0|positive-int', 'str'=>'string', 'encoding='=>'string'],
 'mb_substitute_character' => ['mixed', 'substchar='=>'mixed'],
@@ -12085,7 +12085,7 @@
 'strstr' => ['string|false', 'haystack'=>'string', 'needle'=>'mixed', 'before_needle='=>'bool'],
 'strtok' => ['non-empty-string|false', 'str'=>'string', 'token'=>'string'],
 'strtok\'1' => ['non-empty-string|false', 'token'=>'string'],
-'strtolower' => ['string', 'str'=>'string'],
+'strtolower' => ['lowercase-string', 'str'=>'string'],
 'strtotime' => ['int|false', 'time'=>'string', 'now='=>'int'],
 'strtoupper' => ['string', 'str'=>'string'],
 'strtr' => ['string', 'str'=>'string', 'from'=>'string', 'to'=>'string'],

From 85180dc1073578a90d6d697ae41669f0ba1a86bf Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Fri, 13 Sep 2024 09:10:19 +0200
Subject: [PATCH 03/26] Update StrCaseReturnType

---
 .../StrCaseFunctionsReturnTypeExtension.php   | 38 +++++++++++--------
 tests/PHPStan/Analyser/nsrt/str-casing.php    | 37 ++++++++++++------
 2 files changed, 49 insertions(+), 26 deletions(-)

diff --git a/src/Type/Php/StrCaseFunctionsReturnTypeExtension.php b/src/Type/Php/StrCaseFunctionsReturnTypeExtension.php
index 39355b579e..01f2fb8006 100644
--- a/src/Type/Php/StrCaseFunctionsReturnTypeExtension.php
+++ b/src/Type/Php/StrCaseFunctionsReturnTypeExtension.php
@@ -5,6 +5,7 @@
 use PhpParser\Node\Expr\FuncCall;
 use PHPStan\Analyser\Scope;
 use PHPStan\Reflection\FunctionReflection;
+use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
 use PHPStan\Type\Accessory\AccessoryNonFalsyStringType;
 use PHPStan\Type\Accessory\AccessoryNumericStringType;
@@ -65,9 +66,14 @@ public function getTypeFromFunctionCall(
 		}
 
 		$modes = [];
+		$keepLowercase = false;
+		$forceLowercase = false;
+
 		if ($fnName === 'mb_convert_case') {
 			$modeType = $scope->getType($args[1]->value);
 			$modes = array_map(static fn ($mode) => $mode->getValue(), TypeUtils::getConstantIntegers($modeType));
+			$forceLowercase = count(array_diff($modes, [MB_CASE_LOWER, MB_CASE_LOWER_SIMPLE])) === 0;
+			$keepLowercase = count(array_diff($modes, [MB_CASE_LOWER, MB_CASE_LOWER_SIMPLE, MB_CASE_FOLD, MB_CASE_FOLD_SIMPLE])) === 0;
 		} elseif (in_array($fnName, ['ucwords', 'mb_convert_kana'], true)) {
 			if (count($args) >= 2) {
 				$modeType = $scope->getType($args[1]->value);
@@ -75,6 +81,10 @@ public function getTypeFromFunctionCall(
 			} else {
 				$modes = $fnName === 'mb_convert_kana' ? ['KV'] : [" \t\r\n\f\v"];
 			}
+		} elseif (in_array($fnName, ['strtolower', 'mb_strtolower'])) {
+			$forceLowercase = true;
+		} elseif (in_array($fnName, ['lcfirst', 'mb_lcfirst'])) {
+			$keepLowercase = true;
 		}
 
 		$constantStrings = array_map(static fn ($type) => $type->getValue(), $argType->getConstantStrings());
@@ -101,25 +111,23 @@ public function getTypeFromFunctionCall(
 			}
 		}
 
-		if ($argType->isNumericString()->yes()) {
-			return new IntersectionType([
-				new StringType(),
-				new AccessoryNumericStringType(),
-			]);
+		$accessoryTypes = [];
+		if ($forceLowercase || ($keepLowercase && $argType->isLowercaseString()->yes())) {
+			$accessoryTypes[] = new AccessoryLowercaseStringType();
 		}
 
-		if ($argType->isNonFalsyString()->yes()) {
-			return new IntersectionType([
-				new StringType(),
-				new AccessoryNonFalsyStringType(),
-			]);
+		if ($argType->isNumericString()->yes()) {
+			$accessoryTypes[] = new AccessoryNumericStringType();
+		} elseif ($argType->isNonFalsyString()->yes()) {
+			$accessoryTypes[] = new AccessoryNonFalsyStringType();
+		} elseif ($argType->isNonEmptyString()->yes()) {
+			$accessoryTypes[] = new AccessoryNonEmptyStringType();
 		}
 
-		if ($argType->isNonEmptyString()->yes()) {
-			return new IntersectionType([
-				new StringType(),
-				new AccessoryNonEmptyStringType(),
-			]);
+		if (count($accessoryTypes) > 0) {
+			$accessoryTypes[] = new StringType();
+
+			return new IntersectionType($accessoryTypes);
 		}
 
 		return new StringType();
diff --git a/tests/PHPStan/Analyser/nsrt/str-casing.php b/tests/PHPStan/Analyser/nsrt/str-casing.php
index df4883845a..3f0c76f250 100644
--- a/tests/PHPStan/Analyser/nsrt/str-casing.php
+++ b/tests/PHPStan/Analyser/nsrt/str-casing.php
@@ -8,13 +8,14 @@ class Foo {
 	/**
 	 * @param numeric-string $numericS
 	 * @param non-empty-string $nonE
+	 * @param lowercase-string $lowercaseS
 	 * @param literal-string $literal
 	 * @param 'foo'|'Foo' $edgeUnion
 	 * @param MB_CASE_UPPER|MB_CASE_LOWER|MB_CASE_TITLE|MB_CASE_FOLD|MB_CASE_UPPER_SIMPLE|MB_CASE_LOWER_SIMPLE|MB_CASE_TITLE_SIMPLE|MB_CASE_FOLD_SIMPLE $caseMode
 	 * @param 'aKV'|'hA'|'AH'|'K'|'KV'|'RNKV' $kanaMode
 	 * @param mixed $mixed
 	 */
-	public function bar($numericS, $nonE, $literal, $edgeUnion, $caseMode, $kanaMode, $mixed) {
+	public function bar($numericS, $nonE, $lowercaseS, $literal, $edgeUnion, $caseMode, $kanaMode, $mixed) {
 		assertType("'abc'", strtolower('ABC'));
 		assertType("'ABC'", strtoupper('abc'));
 		assertType("'abc'", mb_strtolower('ABC'));
@@ -37,51 +38,65 @@ public function bar($numericS, $nonE, $literal, $edgeUnion, $caseMode, $kanaMode
 		assertType("'Abc123アガば漢'|'Ａｂｃ１２３あか゛ば漢'|'Ａｂｃ１２３アカ゛ば漢'|'Ａｂｃ１２３アガば漢'|'Ａｂｃ１２３ｱｶﾞﾊﾞ漢'", mb_convert_kana('Ａｂｃ１２３ｱｶﾞば漢', $kanaMode));
 		assertType("non-falsy-string", mb_convert_kana('Ａｂｃ１２３ｱｶﾞば漢', $mixed));
 
-		assertType("numeric-string", strtolower($numericS));
+		assertType("lowercase-string&numeric-string", strtolower($numericS));
 		assertType("numeric-string", strtoupper($numericS));
-		assertType("numeric-string", mb_strtolower($numericS));
+		assertType("lowercase-string&numeric-string", mb_strtolower($numericS));
 		assertType("numeric-string", mb_strtoupper($numericS));
 		assertType("numeric-string", lcfirst($numericS));
 		assertType("numeric-string", ucfirst($numericS));
 		assertType("numeric-string", ucwords($numericS));
 		assertType("numeric-string", mb_convert_case($numericS, MB_CASE_UPPER));
-		assertType("numeric-string", mb_convert_case($numericS, MB_CASE_LOWER));
+		assertType("lowercase-string&numeric-string", mb_convert_case($numericS, MB_CASE_LOWER));
 		assertType("numeric-string", mb_convert_case($numericS, $mixed));
 		assertType("numeric-string", mb_convert_kana($numericS));
 		assertType("numeric-string", mb_convert_kana($numericS, $mixed));
 
-		assertType("non-empty-string", strtolower($nonE));
+		assertType("lowercase-string&non-empty-string", strtolower($nonE));
 		assertType("non-empty-string", strtoupper($nonE));
-		assertType("non-empty-string", mb_strtolower($nonE));
+		assertType("lowercase-string&non-empty-string", mb_strtolower($nonE));
 		assertType("non-empty-string", mb_strtoupper($nonE));
 		assertType("non-empty-string", lcfirst($nonE));
 		assertType("non-empty-string", ucfirst($nonE));
 		assertType("non-empty-string", ucwords($nonE));
 		assertType("non-empty-string", mb_convert_case($nonE, MB_CASE_UPPER));
-		assertType("non-empty-string", mb_convert_case($nonE, MB_CASE_LOWER));
+		assertType("lowercase-string&non-empty-string", mb_convert_case($nonE, MB_CASE_LOWER));
 		assertType("non-empty-string", mb_convert_case($nonE, $mixed));
 		assertType("non-empty-string", mb_convert_kana($nonE));
 		assertType("non-empty-string", mb_convert_kana($nonE, $mixed));
 
-		assertType("string", strtolower($literal));
+		assertType("lowercase-string", strtolower($literal));
 		assertType("string", strtoupper($literal));
-		assertType("string", mb_strtolower($literal));
+		assertType("lowercase-string", mb_strtolower($literal));
 		assertType("string", mb_strtoupper($literal));
 		assertType("string", lcfirst($literal));
 		assertType("string", ucfirst($literal));
 		assertType("string", ucwords($literal));
 		assertType("string", mb_convert_case($literal, MB_CASE_UPPER));
-		assertType("string", mb_convert_case($literal, MB_CASE_LOWER));
+		assertType("lowercase-string", mb_convert_case($literal, MB_CASE_LOWER));
 		assertType("string", mb_convert_case($literal, $mixed));
 		assertType("string", mb_convert_kana($literal));
 		assertType("string", mb_convert_kana($literal, $mixed));
 
+		assertType("lowercase-string", strtolower($lowercaseS));
+		assertType("string", strtoupper($lowercaseS));
+		assertType("lowercase-string", mb_strtolower($lowercaseS));
+		assertType("string", mb_strtoupper($lowercaseS));
+		assertType("lowercase-string", lcfirst($lowercaseS));
+		assertType("string", ucfirst($lowercaseS));
+		assertType("string", ucwords($lowercaseS));
+		assertType("string", mb_convert_case($lowercaseS, MB_CASE_UPPER));
+		assertType("lowercase-string", mb_convert_case($lowercaseS, MB_CASE_LOWER));
+		assertType("string", mb_convert_case($lowercaseS, $mixed));
+		assertType("lowercase-string", mb_convert_case($lowercaseS, rand(0, 1) ? MB_CASE_LOWER : MB_CASE_LOWER_SIMPLE));
+		assertType("string", mb_convert_kana($lowercaseS));
+		assertType("string", mb_convert_kana($lowercaseS, $mixed));
+
 		assertType("'foo'", lcfirst($edgeUnion));
 	}
 
 	public function foo() {
 		// invalid char conversions still lead to non-falsy-string
-		assertType("non-falsy-string", mb_strtolower("\xfe\xff\x65\xe5\x67\x2c\x8a\x9e", 'CP1252'));
+		assertType("lowercase-string&non-falsy-string", mb_strtolower("\xfe\xff\x65\xe5\x67\x2c\x8a\x9e", 'CP1252'));
 		// valid char sequence, but not support non ASCII / UTF-8 encodings
 		assertType("non-falsy-string", mb_convert_kana("\x95\x5c\x8c\xbb", 'SJIS-win'));
 		// invalid UTF-8 sequence

From 716942ef51b211686085d6c39586f3dc751e8aad Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Fri, 13 Sep 2024 10:06:11 +0200
Subject: [PATCH 04/26] Fix tests

---
 src/Rules/Api/ApiInstanceofTypeRule.php            |  2 ++
 src/Type/Constant/ConstantStringType.php           |  5 +++++
 src/Type/IntersectionType.php                      |  3 +++
 .../Php/StrCaseFunctionsReturnTypeExtension.php    | 14 ++++++++++++--
 src/Type/VerbosityLevel.php                        |  2 ++
 .../Analyser/LegacyNodeScopeResolverTest.php       |  2 +-
 tests/PHPStan/Analyser/ScopeTest.php               |  6 +++---
 tests/PHPStan/Analyser/nsrt/bug-2911.php           |  2 +-
 tests/PHPStan/Analyser/nsrt/bug7856.php            |  2 +-
 tests/PHPStan/Analyser/nsrt/non-empty-string.php   |  8 ++++----
 tests/PHPStan/Analyser/nsrt/non-falsy-string.php   |  4 ++--
 tests/PHPStan/PhpDoc/TypeDescriptionTest.php       |  2 ++
 tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php |  2 +-
 .../Type/Constant/ConstantStringTypeTest.php       |  4 ++--
 .../Type/Constant/OversizedArrayBuilderTest.php    |  4 ++--
 tests/PHPStan/Type/TypeToPhpDocNodeTest.php        |  8 +++++++-
 16 files changed, 50 insertions(+), 20 deletions(-)

diff --git a/src/Rules/Api/ApiInstanceofTypeRule.php b/src/Rules/Api/ApiInstanceofTypeRule.php
index 1ae24aa0ca..225e65b000 100644
--- a/src/Rules/Api/ApiInstanceofTypeRule.php
+++ b/src/Rules/Api/ApiInstanceofTypeRule.php
@@ -11,6 +11,7 @@
 use PHPStan\Rules\RuleErrorBuilder;
 use PHPStan\Type\Accessory\AccessoryArrayListType;
 use PHPStan\Type\Accessory\AccessoryLiteralStringType;
+use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
 use PHPStan\Type\Accessory\AccessoryNonFalsyStringType;
 use PHPStan\Type\Accessory\AccessoryNumericStringType;
@@ -84,6 +85,7 @@ final class ApiInstanceofTypeRule implements Rule
 		AccessoryArrayListType::class => 'Type::isList()',
 		AccessoryNumericStringType::class => 'Type::isNumericString()',
 		AccessoryLiteralStringType::class => 'Type::isLiteralString()',
+		AccessoryLowercaseStringType::class => 'Type::isLowercaseString()',
 		AccessoryNonEmptyStringType::class => 'Type::isNonEmptyString()',
 		AccessoryNonFalsyStringType::class => 'Type::isNonFalsyString()',
 		HasMethodType::class => 'Type::hasMethod()',
diff --git a/src/Type/Constant/ConstantStringType.php b/src/Type/Constant/ConstantStringType.php
index 4c42ce01d4..6468944221 100644
--- a/src/Type/Constant/ConstantStringType.php
+++ b/src/Type/Constant/ConstantStringType.php
@@ -20,6 +20,7 @@
 use PHPStan\ShouldNotHappenException;
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\Accessory\AccessoryLiteralStringType;
+use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
 use PHPStan\Type\Accessory\AccessoryNonFalsyStringType;
 use PHPStan\Type\Accessory\AccessoryNumericStringType;
@@ -455,6 +456,10 @@ public function generalize(GeneralizePrecision $precision): Type
 				$accessories[] = new AccessoryNonEmptyStringType();
 			}
 
+			if (strtolower($this->getValue()) === $this->getValue()) {
+				$accessories[] = new AccessoryLowercaseStringType();
+			}
+
 			return new IntersectionType($accessories);
 		}
 
diff --git a/src/Type/IntersectionType.php b/src/Type/IntersectionType.php
index 7a81ed039c..49647a52cd 100644
--- a/src/Type/IntersectionType.php
+++ b/src/Type/IntersectionType.php
@@ -21,6 +21,7 @@
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\Accessory\AccessoryArrayListType;
 use PHPStan\Type\Accessory\AccessoryLiteralStringType;
+use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
 use PHPStan\Type\Accessory\AccessoryNonFalsyStringType;
 use PHPStan\Type\Accessory\AccessoryNumericStringType;
@@ -328,6 +329,7 @@ private function describeItself(VerbosityLevel $level, bool $skipAccessoryTypes)
 				|| $type instanceof AccessoryLiteralStringType
 				|| $type instanceof AccessoryNumericStringType
 				|| $type instanceof AccessoryNonFalsyStringType
+				|| $type instanceof AccessoryLowercaseStringType
 			) {
 				if ($type instanceof AccessoryNonFalsyStringType) {
 					$nonFalsyStr = true;
@@ -1119,6 +1121,7 @@ public function toPhpDocNode(): TypeNode
 				|| $type instanceof AccessoryLiteralStringType
 				|| $type instanceof AccessoryNumericStringType
 				|| $type instanceof AccessoryNonFalsyStringType
+				|| $type instanceof AccessoryLowercaseStringType
 			) {
 				if ($type instanceof AccessoryNonFalsyStringType) {
 					$nonFalsyStr = true;
diff --git a/src/Type/Php/StrCaseFunctionsReturnTypeExtension.php b/src/Type/Php/StrCaseFunctionsReturnTypeExtension.php
index 01f2fb8006..376080e3ef 100644
--- a/src/Type/Php/StrCaseFunctionsReturnTypeExtension.php
+++ b/src/Type/Php/StrCaseFunctionsReturnTypeExtension.php
@@ -72,8 +72,18 @@ public function getTypeFromFunctionCall(
 		if ($fnName === 'mb_convert_case') {
 			$modeType = $scope->getType($args[1]->value);
 			$modes = array_map(static fn ($mode) => $mode->getValue(), TypeUtils::getConstantIntegers($modeType));
-			$forceLowercase = count(array_diff($modes, [MB_CASE_LOWER, MB_CASE_LOWER_SIMPLE])) === 0;
-			$keepLowercase = count(array_diff($modes, [MB_CASE_LOWER, MB_CASE_LOWER_SIMPLE, MB_CASE_FOLD, MB_CASE_FOLD_SIMPLE])) === 0;
+			if (count($modes) > 0) {
+				$forceLowercase = count(array_diff($modes, [
+						MB_CASE_LOWER,
+						MB_CASE_LOWER_SIMPLE,
+					])) === 0;
+				$keepLowercase = count(array_diff($modes, [
+						MB_CASE_LOWER,
+						MB_CASE_LOWER_SIMPLE,
+						MB_CASE_FOLD,
+						MB_CASE_FOLD_SIMPLE,
+					])) === 0;
+			}
 		} elseif (in_array($fnName, ['ucwords', 'mb_convert_kana'], true)) {
 			if (count($args) >= 2) {
 				$modeType = $scope->getType($args[1]->value);
diff --git a/src/Type/VerbosityLevel.php b/src/Type/VerbosityLevel.php
index d9724fc64d..086401052f 100644
--- a/src/Type/VerbosityLevel.php
+++ b/src/Type/VerbosityLevel.php
@@ -4,6 +4,7 @@
 
 use PHPStan\Type\Accessory\AccessoryArrayListType;
 use PHPStan\Type\Accessory\AccessoryLiteralStringType;
+use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
 use PHPStan\Type\Accessory\AccessoryNonFalsyStringType;
 use PHPStan\Type\Accessory\AccessoryNumericStringType;
@@ -101,6 +102,7 @@ public static function getRecommendedLevelByType(Type $acceptingType, ?Type $acc
 				|| $type instanceof AccessoryNonFalsyStringType
 				|| $type instanceof AccessoryLiteralStringType
 				|| $type instanceof AccessoryNumericStringType
+				|| $type instanceof AccessoryLowercaseStringType
 				|| $type instanceof NonEmptyArrayType
 				|| $type instanceof AccessoryArrayListType
 			) {
diff --git a/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php b/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
index 234bbb82d3..f03df64fa6 100644
--- a/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
+++ b/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
@@ -8093,7 +8093,7 @@ public function dataArrayKeysInBranches(): array
 				'$arrayAppendedInForeach',
 			],
 			[
-				'non-empty-array<int<0, max>, literal-string&non-falsy-string>', // could be 'array<int<0, max>, \'bar\'|\'baz\'|\'foo\'>'
+				'non-empty-array<int<0, max>, literal-string&lowercase-string&non-falsy-string>', // could be 'array<int<0, max>, \'bar\'|\'baz\'|\'foo\'>'
 				'$anotherArrayAppendedInForeach',
 			],
 			[
diff --git a/tests/PHPStan/Analyser/ScopeTest.php b/tests/PHPStan/Analyser/ScopeTest.php
index 99bba5ea9b..fe0644cd30 100644
--- a/tests/PHPStan/Analyser/ScopeTest.php
+++ b/tests/PHPStan/Analyser/ScopeTest.php
@@ -29,7 +29,7 @@ public function dataGeneralize(): array
 			[
 				new ConstantStringType('a'),
 				new ConstantStringType('b'),
-				'literal-string&non-falsy-string',
+				'literal-string&lowercase-string&non-falsy-string',
 			],
 			[
 				new ConstantIntegerType(0),
@@ -139,7 +139,7 @@ public function dataGeneralize(): array
 					new ConstantIntegerType(1),
 					new ConstantIntegerType(1),
 				]),
-				'non-empty-array<literal-string&non-falsy-string, 1>',
+				'non-empty-array<literal-string&lowercase-string&non-falsy-string, 1>',
 			],
 			[
 				new ConstantArrayType([
@@ -154,7 +154,7 @@ public function dataGeneralize(): array
 					new ConstantIntegerType(1),
 					new ConstantIntegerType(2),
 				]),
-				'non-empty-array<literal-string&non-falsy-string, int<1, max>>',
+				'non-empty-array<literal-string&lowercase-string&non-falsy-string, int<1, max>>',
 			],
 			[
 				new UnionType([
diff --git a/tests/PHPStan/Analyser/nsrt/bug-2911.php b/tests/PHPStan/Analyser/nsrt/bug-2911.php
index 1544279ea2..1d75efdcbe 100644
--- a/tests/PHPStan/Analyser/nsrt/bug-2911.php
+++ b/tests/PHPStan/Analyser/nsrt/bug-2911.php
@@ -59,7 +59,7 @@ private function getResultSettings(array $settings): array
 
 		$settings['remove'] = strtolower($settings['remove']);
 
-		assertType("non-empty-array<string, mixed>&hasOffsetValue('remove', string)", $settings);
+		assertType("non-empty-array<string, mixed>&hasOffsetValue('remove', lowercase-string)", $settings);
 
 		if (!in_array($settings['remove'], ['first', 'last', 'all'], true)) {
 			throw $this->configException($settings, 'remove');
diff --git a/tests/PHPStan/Analyser/nsrt/bug7856.php b/tests/PHPStan/Analyser/nsrt/bug7856.php
index 0b48d36ebc..fcdca30b44 100644
--- a/tests/PHPStan/Analyser/nsrt/bug7856.php
+++ b/tests/PHPStan/Analyser/nsrt/bug7856.php
@@ -10,7 +10,7 @@ function doFoo() {
 	$endDate = new DateTimeImmutable('+1year');
 
 	do {
-		assertType("array{'+1week', '+1months', '+6months', '+17months'}|array{0: literal-string&non-falsy-string, 1?: literal-string&non-falsy-string, 2?: '+17months'}", $intervals);
+		assertType("array{'+1week', '+1months', '+6months', '+17months'}|array{0: literal-string&lowercase-string&non-falsy-string, 1?: literal-string&lowercase-string&non-falsy-string, 2?: '+17months'}", $intervals);
 		$periodEnd = $periodEnd->modify(array_shift($intervals));
 	} while (count($intervals) > 0 && $periodEnd->format('U') < $endDate);
 }
diff --git a/tests/PHPStan/Analyser/nsrt/non-empty-string.php b/tests/PHPStan/Analyser/nsrt/non-empty-string.php
index 78e536a735..c5554194f6 100644
--- a/tests/PHPStan/Analyser/nsrt/non-empty-string.php
+++ b/tests/PHPStan/Analyser/nsrt/non-empty-string.php
@@ -320,12 +320,12 @@ public function doFoo(string $s, string $nonEmpty, string $nonFalsy, int $i, boo
 
 		assertType('string', strtoupper($s));
 		assertType('non-empty-string', strtoupper($nonEmpty));
-		assertType('string', strtolower($s));
-		assertType('non-empty-string', strtolower($nonEmpty));
+		assertType('lowercase-string', strtolower($s));
+		assertType('lowercase-string&non-empty-string', strtolower($nonEmpty));
 		assertType('string', mb_strtoupper($s));
 		assertType('non-empty-string', mb_strtoupper($nonEmpty));
-		assertType('string', mb_strtolower($s));
-		assertType('non-empty-string', mb_strtolower($nonEmpty));
+		assertType('lowercase-string', mb_strtolower($s));
+		assertType('lowercase-string&non-empty-string', mb_strtolower($nonEmpty));
 		assertType('string', lcfirst($s));
 		assertType('non-empty-string', lcfirst($nonEmpty));
 		assertType('string', ucfirst($s));
diff --git a/tests/PHPStan/Analyser/nsrt/non-falsy-string.php b/tests/PHPStan/Analyser/nsrt/non-falsy-string.php
index f8c6dc40b7..4127dd5870 100644
--- a/tests/PHPStan/Analyser/nsrt/non-falsy-string.php
+++ b/tests/PHPStan/Analyser/nsrt/non-falsy-string.php
@@ -88,9 +88,9 @@ function stringFunctions(string $s, $nonFalsey, $arrayOfNonFalsey, $nonEmptyArra
 		assertType('non-falsy-string', escapeshellcmd($nonFalsey));
 
 		assertType('non-falsy-string', strtoupper($nonFalsey));
-		assertType('non-falsy-string', strtolower($nonFalsey));
+		assertType('lowercase-string&non-falsy-string', strtolower($nonFalsey));
 		assertType('non-falsy-string', mb_strtoupper($nonFalsey));
-		assertType('non-falsy-string', mb_strtolower($nonFalsey));
+		assertType('lowercase-string&non-falsy-string', mb_strtolower($nonFalsey));
 		assertType('non-falsy-string', lcfirst($nonFalsey));
 		assertType('non-falsy-string', ucfirst($nonFalsey));
 		assertType('non-falsy-string', ucwords($nonFalsey));
diff --git a/tests/PHPStan/PhpDoc/TypeDescriptionTest.php b/tests/PHPStan/PhpDoc/TypeDescriptionTest.php
index 29c3a35231..7c0b2e9cc1 100644
--- a/tests/PHPStan/PhpDoc/TypeDescriptionTest.php
+++ b/tests/PHPStan/PhpDoc/TypeDescriptionTest.php
@@ -4,6 +4,7 @@
 
 use PHPStan\Testing\PHPStanTestCase;
 use PHPStan\Type\Accessory\AccessoryLiteralStringType;
+use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
 use PHPStan\Type\Accessory\AccessoryNumericStringType;
 use PHPStan\Type\Accessory\NonEmptyArrayType;
@@ -29,6 +30,7 @@ public function dataTest(): iterable
 		yield ['string', new StringType()];
 		yield ['array', new ArrayType(new MixedType(), new MixedType())];
 		yield ['literal-string', new IntersectionType([new StringType(), new AccessoryLiteralStringType()])];
+		yield ['lowercase-string', new IntersectionType([new StringType(), new AccessoryLowercaseStringType()])];
 		yield ['non-empty-string', new IntersectionType([new StringType(), new AccessoryNonEmptyStringType()])];
 		yield ['numeric-string', new IntersectionType([new StringType(), new AccessoryNumericStringType()])];
 		yield ['literal-string&non-empty-string', new IntersectionType([new StringType(), new AccessoryLiteralStringType(), new AccessoryNonEmptyStringType()])];
diff --git a/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php b/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php
index 6d374a6f1c..b8627bfee5 100644
--- a/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php
+++ b/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php
@@ -834,7 +834,7 @@ public function testBug8146bErrors(): void
 		$this->checkBenevolentUnionTypes = true;
 		$this->analyse([__DIR__ . '/data/bug-8146b-errors.php'], [
 			[
-				"Method Bug8146bError\LocationFixtures::getData() should return array<non-empty-string, array<non-empty-string, array{constituencies: non-empty-list<non-empty-string>, coordinates: array{lat: float, lng: float}}>> but returns array{Bács-Kiskun: array{Ágasegyháza: array{constituencies: array{'Bács-Kiskun 4.', true, false, Bug8146bError\X, null}, coordinates: array{lat: 46.8386043, lng: 19.4502899}}, Akasztó: array{constituencies: array{'Bács-Kiskun 3.'}, coordinates: array{lat: 46.6898175, lng: 19.205086}}, Apostag: array{constituencies: array{'Bács-Kiskun 3.'}, coordinates: array{lat: 46.8812652, lng: 18.9648478}}, Bácsalmás: array{constituencies: array{'Bács-Kiskun 5.'}, coordinates: array{lat: 46.1250396, lng: 19.3357509}}, Bácsbokod: array{constituencies: array{'Bács-Kiskun 6.'}, coordinates: array{lat: 46.1234737, lng: 19.155708}}, Bácsborsód: array{constituencies: array{'Bács-Kiskun 6.'}, coordinates: array{lat: 46.0989373, lng: 19.1566725}}, Bácsszentgyörgy: array{constituencies: array{'Bács-Kiskun 6.'}, coordinates: array{lat: 45.9746039, lng: 19.0398066}}, Bácsszőlős: array{constituencies: array{'Bács-Kiskun 5.'}, coordinates: array{lat: 46.1352003, lng: 19.4215997}}, ...}, Baranya: non-empty-array<literal-string&non-falsy-string, array<literal-string&non-falsy-string, array<int<0, max>|(literal-string&non-falsy-string), float|(literal-string&non-falsy-string)>>>, Békés: array{Almáskamarás: array{constituencies: array{'Békés 4.'}, coordinates: array{lat: 46.4617785, lng: 21.092448}}, Battonya: array{constituencies: array{'Békés 4.'}, coordinates: array{lat: 46.2902462, lng: 21.0199215}}, Békés: array{constituencies: array{'Békés 2.'}, coordinates: array{lat: 46.6704899, lng: 21.0434996}}, Békéscsaba: array{constituencies: array{'Békés 1.'}, coordinates: array{lat: 46.6735939, lng: 21.0877309}}, Békéssámson: array{constituencies: array{'Békés 4.'}, coordinates: array{lat: 46.4208677, lng: 20.6176498}}, Békésszentandrás: array{constituencies: array{'Békés 2.'}, coordinates: array{lat: 46.8715996, lng: 20.48336}}, Bélmegyer: array{constituencies: array{'Békés 3.'}, coordinates: array{lat: 46.8726019, lng: 21.1832832}}, Biharugra: array{constituencies: array{'Békés 3.'}, coordinates: array{lat: 46.9691009, lng: 21.5987651}}, ...}, Borsod-Abaúj-Zemplén: non-empty-array<literal-string&non-falsy-string, array<literal-string&non-falsy-string, array<int<0, max>|(literal-string&non-falsy-string), float|(literal-string&non-falsy-string)>>>, Budapest: array{Budapest I. ker.: array{constituencies: array{'Budapest 01.'}, coordinates: array{lat: 47.4968219, lng: 19.037458}}, Budapest II. ker.: array{constituencies: array{'Budapest 03.', 'Budapest 04.'}, coordinates: array{lat: 47.5393329, lng: 18.986934}}, Budapest III. ker.: array{constituencies: array{'Budapest 04.', 'Budapest 10.'}, coordinates: array{lat: 47.5671768, lng: 19.0368517}}, Budapest IV. ker.: array{constituencies: array{'Budapest 11.', 'Budapest 12.'}, coordinates: array{lat: 47.5648915, lng: 19.0913149}}, Budapest V. ker.: array{constituencies: array{'Budapest 01.'}, coordinates: array{lat: 47.5002319, lng: 19.0520181}}, Budapest VI. ker.: array{constituencies: array{'Budapest 05.'}, coordinates: array{lat: 47.509863, lng: 19.0625813}}, Budapest VII. ker.: array{constituencies: array{'Budapest 05.'}, coordinates: array{lat: 47.5027289, lng: 19.073376}}, Budapest VIII. ker.: array{constituencies: array{'Budapest 01.', 'Budapest 06.'}, coordinates: array{lat: 47.4894184, lng: 19.070668}}, ...}, Csongrád-Csanád: array{Algyő: array{constituencies: array{'Csongrád-Csanád 4.'}, coordinates: array{lat: 46.3329625, lng: 20.207889}}, Ambrózfalva: array{constituencies: array{'Csongrád-Csanád 4.'}, coordinates: array{lat: 46.3501417, lng: 20.7313995}}, Apátfalva: array{constituencies: array{'Csongrád-Csanád 4.'}, coordinates: array{lat: 46.173317, lng: 20.5800472}}, Árpádhalom: array{constituencies: array{'Csongrád-Csanád 3.'}, coordinates: array{lat: 46.6158286, lng: 20.547733}}, Ásotthalom: array{constituencies: array{'Csongrád-Csanád 2.'}, coordinates: array{lat: 46.1995983, lng: 19.7833756}}, Baks: array{constituencies: array{'Csongrád-Csanád 3.'}, coordinates: array{lat: 46.5518708, lng: 20.1064166}}, Balástya: array{constituencies: array{'Csongrád-Csanád 3.'}, coordinates: array{lat: 46.4261828, lng: 20.004933}}, Bordány: array{constituencies: array{'Csongrád-Csanád 2.'}, coordinates: array{lat: 46.3194213, lng: 19.9227063}}, ...}, Fejér: array{Aba: array{constituencies: array{'Fejér 5.'}, coordinates: array{lat: 47.0328193, lng: 18.522359}}, Adony: array{constituencies: array{'Fejér 4.'}, coordinates: array{lat: 47.119831, lng: 18.8612469}}, Alap: array{constituencies: array{'Fejér 5.'}, coordinates: array{lat: 46.8075763, lng: 18.684028}}, Alcsútdoboz: array{constituencies: array{'Fejér 3.'}, coordinates: array{lat: 47.4277067, lng: 18.6030325}}, Alsószentiván: array{constituencies: array{'Fejér 5.'}, coordinates: array{lat: 46.7910573, lng: 18.732161}}, Bakonycsernye: array{constituencies: array{'Fejér 2.'}, coordinates: array{lat: 47.321719, lng: 18.0907379}}, Bakonykúti: array{constituencies: array{'Fejér 2.'}, coordinates: array{lat: 47.2458464, lng: 18.195769}}, Balinka: array{constituencies: array{'Fejér 2.'}, coordinates: array{lat: 47.3135736, lng: 18.1907168}}, ...}, Győr-Moson-Sopron: array{Abda: array{constituencies: array{'Győr-Moson-Sopron 5.'}, coordinates: array{lat: 47.6962149, lng: 17.5445786}}, Acsalag: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.676095, lng: 17.1977771}}, Ágfalva: array{constituencies: array{'Győr-Moson-Sopron 4.'}, coordinates: array{lat: 47.688862, lng: 16.5110233}}, Agyagosszergény: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.608545, lng: 16.9409912}}, Árpás: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.5134127, lng: 17.3931579}}, Ásványráró: array{constituencies: array{'Győr-Moson-Sopron 5.'}, coordinates: array{lat: 47.8287695, lng: 17.499195}}, Babót: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.5752269, lng: 17.0758604}}, Bágyogszovát: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.5866036, lng: 17.3617273}}, ...}, ...}.",
+				"Method Bug8146bError\LocationFixtures::getData() should return array<non-empty-string, array<non-empty-string, array{constituencies: non-empty-list<non-empty-string>, coordinates: array{lat: float, lng: float}}>> but returns array{Bács-Kiskun: array{Ágasegyháza: array{constituencies: array{'Bács-Kiskun 4.', true, false, Bug8146bError\X, null}, coordinates: array{lat: 46.8386043, lng: 19.4502899}}, Akasztó: array{constituencies: array{'Bács-Kiskun 3.'}, coordinates: array{lat: 46.6898175, lng: 19.205086}}, Apostag: array{constituencies: array{'Bács-Kiskun 3.'}, coordinates: array{lat: 46.8812652, lng: 18.9648478}}, Bácsalmás: array{constituencies: array{'Bács-Kiskun 5.'}, coordinates: array{lat: 46.1250396, lng: 19.3357509}}, Bácsbokod: array{constituencies: array{'Bács-Kiskun 6.'}, coordinates: array{lat: 46.1234737, lng: 19.155708}}, Bácsborsód: array{constituencies: array{'Bács-Kiskun 6.'}, coordinates: array{lat: 46.0989373, lng: 19.1566725}}, Bácsszentgyörgy: array{constituencies: array{'Bács-Kiskun 6.'}, coordinates: array{lat: 45.9746039, lng: 19.0398066}}, Bácsszőlős: array{constituencies: array{'Bács-Kiskun 5.'}, coordinates: array{lat: 46.1352003, lng: 19.4215997}}, ...}, Baranya: non-empty-array<literal-string&non-falsy-string, array<literal-string&lowercase-string&non-falsy-string, array<int<0, max>|(literal-string&lowercase-string&non-falsy-string), float|(literal-string&non-falsy-string)>>>, Békés: array{Almáskamarás: array{constituencies: array{'Békés 4.'}, coordinates: array{lat: 46.4617785, lng: 21.092448}}, Battonya: array{constituencies: array{'Békés 4.'}, coordinates: array{lat: 46.2902462, lng: 21.0199215}}, Békés: array{constituencies: array{'Békés 2.'}, coordinates: array{lat: 46.6704899, lng: 21.0434996}}, Békéscsaba: array{constituencies: array{'Békés 1.'}, coordinates: array{lat: 46.6735939, lng: 21.0877309}}, Békéssámson: array{constituencies: array{'Békés 4.'}, coordinates: array{lat: 46.4208677, lng: 20.6176498}}, Békésszentandrás: array{constituencies: array{'Békés 2.'}, coordinates: array{lat: 46.8715996, lng: 20.48336}}, Bélmegyer: array{constituencies: array{'Békés 3.'}, coordinates: array{lat: 46.8726019, lng: 21.1832832}}, Biharugra: array{constituencies: array{'Békés 3.'}, coordinates: array{lat: 46.9691009, lng: 21.5987651}}, ...}, Borsod-Abaúj-Zemplén: non-empty-array<literal-string&non-falsy-string, array<literal-string&lowercase-string&non-falsy-string, array<int<0, max>|(literal-string&lowercase-string&non-falsy-string), float|(literal-string&non-falsy-string)>>>, Budapest: array{Budapest I. ker.: array{constituencies: array{'Budapest 01.'}, coordinates: array{lat: 47.4968219, lng: 19.037458}}, Budapest II. ker.: array{constituencies: array{'Budapest 03.', 'Budapest 04.'}, coordinates: array{lat: 47.5393329, lng: 18.986934}}, Budapest III. ker.: array{constituencies: array{'Budapest 04.', 'Budapest 10.'}, coordinates: array{lat: 47.5671768, lng: 19.0368517}}, Budapest IV. ker.: array{constituencies: array{'Budapest 11.', 'Budapest 12.'}, coordinates: array{lat: 47.5648915, lng: 19.0913149}}, Budapest V. ker.: array{constituencies: array{'Budapest 01.'}, coordinates: array{lat: 47.5002319, lng: 19.0520181}}, Budapest VI. ker.: array{constituencies: array{'Budapest 05.'}, coordinates: array{lat: 47.509863, lng: 19.0625813}}, Budapest VII. ker.: array{constituencies: array{'Budapest 05.'}, coordinates: array{lat: 47.5027289, lng: 19.073376}}, Budapest VIII. ker.: array{constituencies: array{'Budapest 01.', 'Budapest 06.'}, coordinates: array{lat: 47.4894184, lng: 19.070668}}, ...}, Csongrád-Csanád: array{Algyő: array{constituencies: array{'Csongrád-Csanád 4.'}, coordinates: array{lat: 46.3329625, lng: 20.207889}}, Ambrózfalva: array{constituencies: array{'Csongrád-Csanád 4.'}, coordinates: array{lat: 46.3501417, lng: 20.7313995}}, Apátfalva: array{constituencies: array{'Csongrád-Csanád 4.'}, coordinates: array{lat: 46.173317, lng: 20.5800472}}, Árpádhalom: array{constituencies: array{'Csongrád-Csanád 3.'}, coordinates: array{lat: 46.6158286, lng: 20.547733}}, Ásotthalom: array{constituencies: array{'Csongrád-Csanád 2.'}, coordinates: array{lat: 46.1995983, lng: 19.7833756}}, Baks: array{constituencies: array{'Csongrád-Csanád 3.'}, coordinates: array{lat: 46.5518708, lng: 20.1064166}}, Balástya: array{constituencies: array{'Csongrád-Csanád 3.'}, coordinates: array{lat: 46.4261828, lng: 20.004933}}, Bordány: array{constituencies: array{'Csongrád-Csanád 2.'}, coordinates: array{lat: 46.3194213, lng: 19.9227063}}, ...}, Fejér: array{Aba: array{constituencies: array{'Fejér 5.'}, coordinates: array{lat: 47.0328193, lng: 18.522359}}, Adony: array{constituencies: array{'Fejér 4.'}, coordinates: array{lat: 47.119831, lng: 18.8612469}}, Alap: array{constituencies: array{'Fejér 5.'}, coordinates: array{lat: 46.8075763, lng: 18.684028}}, Alcsútdoboz: array{constituencies: array{'Fejér 3.'}, coordinates: array{lat: 47.4277067, lng: 18.6030325}}, Alsószentiván: array{constituencies: array{'Fejér 5.'}, coordinates: array{lat: 46.7910573, lng: 18.732161}}, Bakonycsernye: array{constituencies: array{'Fejér 2.'}, coordinates: array{lat: 47.321719, lng: 18.0907379}}, Bakonykúti: array{constituencies: array{'Fejér 2.'}, coordinates: array{lat: 47.2458464, lng: 18.195769}}, Balinka: array{constituencies: array{'Fejér 2.'}, coordinates: array{lat: 47.3135736, lng: 18.1907168}}, ...}, Győr-Moson-Sopron: array{Abda: array{constituencies: array{'Győr-Moson-Sopron 5.'}, coordinates: array{lat: 47.6962149, lng: 17.5445786}}, Acsalag: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.676095, lng: 17.1977771}}, Ágfalva: array{constituencies: array{'Győr-Moson-Sopron 4.'}, coordinates: array{lat: 47.688862, lng: 16.5110233}}, Agyagosszergény: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.608545, lng: 16.9409912}}, Árpás: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.5134127, lng: 17.3931579}}, Ásványráró: array{constituencies: array{'Győr-Moson-Sopron 5.'}, coordinates: array{lat: 47.8287695, lng: 17.499195}}, Babót: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.5752269, lng: 17.0758604}}, Bágyogszovát: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.5866036, lng: 17.3617273}}, ...}, ...}.",
 				12,
 				"Offset 'constituencies' (non-empty-list<non-empty-string>) does not accept type array{'Bács-Kiskun 4.', true, false, Bug8146bError\X, null}.",
 			],
diff --git a/tests/PHPStan/Type/Constant/ConstantStringTypeTest.php b/tests/PHPStan/Type/Constant/ConstantStringTypeTest.php
index 976917737b..ae918cb9a5 100644
--- a/tests/PHPStan/Type/Constant/ConstantStringTypeTest.php
+++ b/tests/PHPStan/Type/Constant/ConstantStringTypeTest.php
@@ -153,8 +153,8 @@ public function testGeneralize(): void
 	{
 		$this->assertSame('literal-string&non-falsy-string', (new ConstantStringType('NonexistentClass'))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
 		$this->assertSame('literal-string', (new ConstantStringType(''))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
-		$this->assertSame('literal-string&non-falsy-string', (new ConstantStringType('a'))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
-		$this->assertSame('literal-string&non-empty-string&numeric-string', (new ConstantStringType('0'))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
+		$this->assertSame('literal-string&lowercase-string&non-falsy-string', (new ConstantStringType('a'))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
+		$this->assertSame('literal-string&lowercase-string&non-empty-string&numeric-string', (new ConstantStringType('0'))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
 		$this->assertSame('literal-string&non-falsy-string&numeric-string', (new ConstantStringType('1.123'))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
 		$this->assertSame('literal-string&non-falsy-string', (new ConstantStringType('    1       1   '))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
 		$this->assertSame('literal-string&non-falsy-string&numeric-string', (new ConstantStringType('+1'))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
diff --git a/tests/PHPStan/Type/Constant/OversizedArrayBuilderTest.php b/tests/PHPStan/Type/Constant/OversizedArrayBuilderTest.php
index e083852496..2e2bcf976c 100644
--- a/tests/PHPStan/Type/Constant/OversizedArrayBuilderTest.php
+++ b/tests/PHPStan/Type/Constant/OversizedArrayBuilderTest.php
@@ -28,7 +28,7 @@ public function dataBuild(): iterable
 
 		yield [
 			'[1, 2, 3, ...[1, \'foo\' => 2, 3]]',
-			'non-empty-array<int|(literal-string&non-falsy-string), int>&oversized-array',
+			'non-empty-array<int|(literal-string&lowercase-string&non-falsy-string), int>&oversized-array',
 		];
 
 		yield [
@@ -49,7 +49,7 @@ public function dataBuild(): iterable
 		];
 		yield [
 			'[1, \'foo\' => 2, 3]',
-			'non-empty-array<int|(literal-string&non-falsy-string), int>&oversized-array',
+			'non-empty-array<int|(literal-string&lowercase-string&non-falsy-string), int>&oversized-array',
 		];
 	}
 
diff --git a/tests/PHPStan/Type/TypeToPhpDocNodeTest.php b/tests/PHPStan/Type/TypeToPhpDocNodeTest.php
index 592271bdda..eebdb08014 100644
--- a/tests/PHPStan/Type/TypeToPhpDocNodeTest.php
+++ b/tests/PHPStan/Type/TypeToPhpDocNodeTest.php
@@ -6,6 +6,7 @@
 use PHPStan\Testing\PHPStanTestCase;
 use PHPStan\Type\Accessory\AccessoryArrayListType;
 use PHPStan\Type\Accessory\AccessoryLiteralStringType;
+use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
 use PHPStan\Type\Accessory\AccessoryNumericStringType;
 use PHPStan\Type\Accessory\NonEmptyArrayType;
@@ -217,6 +218,11 @@ public function dataToPhpDocNode(): iterable
 			'literal-string',
 		];
 
+		yield [
+			new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+			'lowercase-string',
+		];
+
 		yield [
 			new IntersectionType([new StringType(), new AccessoryNonEmptyStringType()]),
 			'non-empty-string',
@@ -324,7 +330,7 @@ public function dataToPhpDocNodeWithoutCheckingEquals(): iterable
 	{
 		yield [
 			new ConstantStringType("foo\nbar\nbaz"),
-			'(literal-string & non-falsy-string)',
+			'(literal-string & lowercase-string & non-falsy-string)',
 		];
 
 		yield [

From ff952eefee1fea9e3c8099779b59d8bd11e88b37 Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Fri, 13 Sep 2024 11:08:58 +0200
Subject: [PATCH 05/26] More dynamicReturnTypes

---
 ...lodeFunctionDynamicReturnTypeExtension.php | 12 ++++++-
 .../ImplodeFunctionReturnTypeExtension.php    |  4 +++
 .../Php/SubstrDynamicReturnTypeExtension.php  | 22 +++++++-----
 .../Analyser/LegacyNodeScopeResolverTest.php  |  6 ++--
 tests/PHPStan/Analyser/nsrt/bug-4711.php      |  4 +--
 .../nsrt/lowercase-string-implode.php         | 36 +++++++++++++++++++
 .../Analyser/nsrt/lowercase-string-subtr.php  | 30 ++++++++++++++++
 .../Analyser/nsrt/non-empty-string-substr.php |  2 +-
 .../Analyser/nsrt/non-empty-string.php        |  2 +-
 ...rictComparisonOfDifferentTypesRuleTest.php |  2 +-
 .../Type/Constant/ConstantStringTypeTest.php  | 12 +++----
 11 files changed, 108 insertions(+), 24 deletions(-)
 create mode 100644 tests/PHPStan/Analyser/nsrt/lowercase-string-implode.php
 create mode 100644 tests/PHPStan/Analyser/nsrt/lowercase-string-subtr.php

diff --git a/src/Type/Php/ExplodeFunctionDynamicReturnTypeExtension.php b/src/Type/Php/ExplodeFunctionDynamicReturnTypeExtension.php
index 9927cc252e..ccad08cefb 100644
--- a/src/Type/Php/ExplodeFunctionDynamicReturnTypeExtension.php
+++ b/src/Type/Php/ExplodeFunctionDynamicReturnTypeExtension.php
@@ -7,6 +7,7 @@
 use PHPStan\Php\PhpVersion;
 use PHPStan\Reflection\FunctionReflection;
 use PHPStan\Type\Accessory\AccessoryArrayListType;
+use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\NonEmptyArrayType;
 use PHPStan\Type\ArrayType;
 use PHPStan\Type\Constant\ConstantBooleanType;
@@ -14,6 +15,7 @@
 use PHPStan\Type\DynamicFunctionReturnTypeExtension;
 use PHPStan\Type\IntegerRangeType;
 use PHPStan\Type\IntegerType;
+use PHPStan\Type\IntersectionType;
 use PHPStan\Type\MixedType;
 use PHPStan\Type\NeverType;
 use PHPStan\Type\StringType;
@@ -54,7 +56,15 @@ public function getTypeFromFunctionCall(
 			return new ConstantBooleanType(false);
 		}
 
-		$returnType = AccessoryArrayListType::intersectWith(new ArrayType(new IntegerType(), new StringType()));
+		$stringType = $scope->getType($args[1]->value);
+		if ($stringType->isLowercaseString()->yes()) {
+			$returnValueType = new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]);
+		} else {
+			$returnValueType = new StringType();
+		}
+
+		$returnType = AccessoryArrayListType::intersectWith(new ArrayType(new IntegerType(), $returnValueType));
+
 		if (
 			!isset($args[2])
 			|| IntegerRangeType::fromInterval(0, null)->isSuperTypeOf($scope->getType($args[2]->value))->yes()
diff --git a/src/Type/Php/ImplodeFunctionReturnTypeExtension.php b/src/Type/Php/ImplodeFunctionReturnTypeExtension.php
index bb29690bd6..d29e20a7cc 100644
--- a/src/Type/Php/ImplodeFunctionReturnTypeExtension.php
+++ b/src/Type/Php/ImplodeFunctionReturnTypeExtension.php
@@ -6,6 +6,7 @@
 use PHPStan\Analyser\Scope;
 use PHPStan\Reflection\FunctionReflection;
 use PHPStan\Type\Accessory\AccessoryLiteralStringType;
+use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
 use PHPStan\Type\Accessory\AccessoryNonFalsyStringType;
 use PHPStan\Type\Constant\ConstantArrayType;
@@ -90,6 +91,9 @@ private function implode(Type $arrayType, Type $separatorType): Type
 		if ($arrayType->getIterableValueType()->isLiteralString()->yes() && $separatorType->isLiteralString()->yes()) {
 			$accessoryTypes[] = new AccessoryLiteralStringType();
 		}
+		if ($arrayType->getIterableValueType()->isLowercaseString()->yes() && $separatorType->isLowercaseString()->yes()) {
+			$accessoryTypes[] = new AccessoryLowercaseStringType();
+		}
 
 		if (count($accessoryTypes) > 0) {
 			$accessoryTypes[] = new StringType();
diff --git a/src/Type/Php/SubstrDynamicReturnTypeExtension.php b/src/Type/Php/SubstrDynamicReturnTypeExtension.php
index f40ff3900d..5edc3f8df4 100644
--- a/src/Type/Php/SubstrDynamicReturnTypeExtension.php
+++ b/src/Type/Php/SubstrDynamicReturnTypeExtension.php
@@ -5,6 +5,7 @@
 use PhpParser\Node\Expr\FuncCall;
 use PHPStan\Analyser\Scope;
 use PHPStan\Reflection\FunctionReflection;
+use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
 use PHPStan\Type\Accessory\AccessoryNonFalsyStringType;
 use PHPStan\Type\Constant\ConstantBooleanType;
@@ -88,18 +89,21 @@ public function getTypeFromFunctionCall(
 			return TypeCombinator::union(...$results);
 		}
 
+		$accessoryTypes = [];
+		if ($string->isLowercaseString()->yes()) {
+			$accessoryTypes[] = new AccessoryLowercaseStringType();
+		}
 		if ($string->isNonEmptyString()->yes() && ($negativeOffset || $zeroOffset && $positiveLength)) {
 			if ($string->isNonFalsyString()->yes() && !$maybeOneLength) {
-				return new IntersectionType([
-					new StringType(),
-					new AccessoryNonFalsyStringType(),
-				]);
-
+				$accessoryTypes[] = new AccessoryNonFalsyStringType();
+			} else {
+				$accessoryTypes[] = new AccessoryNonEmptyStringType();
 			}
-			return new IntersectionType([
-				new StringType(),
-				new AccessoryNonEmptyStringType(),
-			]);
+		}
+		if (count($accessoryTypes) > 0) {
+			$accessoryTypes[] = new StringType();
+
+			return new IntersectionType($accessoryTypes);
 		}
 
 		return null;
diff --git a/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php b/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
index f03df64fa6..0cb675d14b 100644
--- a/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
+++ b/tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php
@@ -1129,11 +1129,11 @@ public function dataArrayDestructuring(): array
 				'$fourthStringArrayForeachList',
 			],
 			[
-				'string',
+				'lowercase-string',
 				'$dateArray[\'Y\']',
 			],
 			[
-				'string',
+				'lowercase-string',
 				'$dateArray[\'m\']',
 			],
 			[
@@ -1141,7 +1141,7 @@ public function dataArrayDestructuring(): array
 				'$dateArray[\'d\']',
 			],
 			[
-				'string',
+				'lowercase-string',
 				'$intArrayForRewritingFirstElement[0]',
 			],
 			[
diff --git a/tests/PHPStan/Analyser/nsrt/bug-4711.php b/tests/PHPStan/Analyser/nsrt/bug-4711.php
index 46bc69565f..8fbed765a9 100644
--- a/tests/PHPStan/Analyser/nsrt/bug-4711.php
+++ b/tests/PHPStan/Analyser/nsrt/bug-4711.php
@@ -12,8 +12,8 @@ function x(string $string): void {
 			return;
 		}
 
-		assertType('non-empty-list<string>', explode($string, ''));
-		assertType('non-empty-list<string>', explode($string[0], ''));
+		assertType('non-empty-list<lowercase-string>', explode($string, ''));
+		assertType('non-empty-list<lowercase-string>', explode($string[0], ''));
 	}
 
 }
diff --git a/tests/PHPStan/Analyser/nsrt/lowercase-string-implode.php b/tests/PHPStan/Analyser/nsrt/lowercase-string-implode.php
new file mode 100644
index 0000000000..19fc961f1f
--- /dev/null
+++ b/tests/PHPStan/Analyser/nsrt/lowercase-string-implode.php
@@ -0,0 +1,36 @@
+<?php
+
+namespace LowercaseStringImplode;
+
+use function htmlspecialchars;
+use function lcfirst;
+use function PHPStan\Testing\assertType;
+use function strtolower;
+use function strtoupper;
+use function ucfirst;
+
+class ExplodingStrings
+{
+	public function doFoo(string $s): void
+	{
+		assertType('non-empty-list<lowercase-string>', explode($s, 'foo'));
+		assertType('non-empty-list<string>', explode($s, 'FOO'));
+	}
+}
+
+class ImplodingStrings
+{
+
+	/**
+	 * @param lowercase-string $ls
+	 * @param array<string> $commonStrings
+	 * @param array<lowercase-string> $lowercaseStrings
+	 */
+	public function doFoo(string $s, string $ls, array $commonStrings, array $lowercaseStrings): void
+	{
+		assertType('string', implode($s, $commonStrings));
+		assertType('string', implode($s, $lowercaseStrings));
+		assertType('string', implode($ls, $commonStrings));
+		assertType('lowercase-string', implode($ls, $lowercaseStrings));
+	}
+}
diff --git a/tests/PHPStan/Analyser/nsrt/lowercase-string-subtr.php b/tests/PHPStan/Analyser/nsrt/lowercase-string-subtr.php
new file mode 100644
index 0000000000..b2a2ff43fa
--- /dev/null
+++ b/tests/PHPStan/Analyser/nsrt/lowercase-string-subtr.php
@@ -0,0 +1,30 @@
+<?php // lint >= 8.0
+
+namespace LowercaseStringSubstr;
+
+use function PHPStan\Testing\assertType;
+
+class Foo
+{
+
+	/**
+	 * @param lowercase-string $lowercase
+	 */
+	public function doSubstr(string $lowercase): void
+	{
+		assertType('lowercase-string', substr($lowercase, 5));
+		assertType('lowercase-string', substr($lowercase, -5));
+		assertType('lowercase-string', substr($lowercase, 0, 5));
+	}
+
+	/**
+	 * @param lowercase-string $lowercase
+	 */
+	public function doMbSubstr(string $lowercase): void
+	{
+		assertType('lowercase-string', mb_substr($lowercase, 5));
+		assertType('lowercase-string', mb_substr($lowercase, -5));
+		assertType('lowercase-string', mb_substr($lowercase, 0, 5));
+	}
+
+}
diff --git a/tests/PHPStan/Analyser/nsrt/non-empty-string-substr.php b/tests/PHPStan/Analyser/nsrt/non-empty-string-substr.php
index c1f85c4df7..42dacb886f 100644
--- a/tests/PHPStan/Analyser/nsrt/non-empty-string-substr.php
+++ b/tests/PHPStan/Analyser/nsrt/non-empty-string-substr.php
@@ -54,7 +54,7 @@ public function doMbSubstr(string $s, $nonEmpty, $positiveInt, $postiveRange, $n
 		assertType('string', mb_substr($s, 0, $positiveInt));
 		assertType('non-empty-string', mb_substr($nonEmpty, 0, $positiveInt));
 
-		assertType('non-empty-string', mb_substr("déjà_vu", 0, $positiveInt));
+		assertType('lowercase-string&non-empty-string', mb_substr("déjà_vu", 0, $positiveInt));
 		assertType("'déjà_vu'", mb_substr("déjà_vu", 0));
 		assertType("'déj'", mb_substr("déjà_vu", 0, 3));
 	}
diff --git a/tests/PHPStan/Analyser/nsrt/non-empty-string.php b/tests/PHPStan/Analyser/nsrt/non-empty-string.php
index c5554194f6..19a5d6b96a 100644
--- a/tests/PHPStan/Analyser/nsrt/non-empty-string.php
+++ b/tests/PHPStan/Analyser/nsrt/non-empty-string.php
@@ -127,7 +127,7 @@ public function doFoo3(string $s): void
 	 */
 	public function doFoo4(string $s): void
 	{
-		assertType('non-empty-list<string>', explode($s, 'foo'));
+		assertType('non-empty-list<lowercase-string>', explode($s, 'foo'));
 	}
 
 	/**
diff --git a/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php b/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php
index 2bfd60e993..fe9b8fa079 100644
--- a/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php
+++ b/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php
@@ -566,7 +566,7 @@ public function testBug6939(): void
 
 		$this->analyse([__DIR__ . '/data/bug-6939.php'], [
 			[
-				'Strict comparison using === between string and false will always evaluate to false.',
+				'Strict comparison using === between lowercase-string and false will always evaluate to false.',
 				10,
 			],
 		]);
diff --git a/tests/PHPStan/Type/Constant/ConstantStringTypeTest.php b/tests/PHPStan/Type/Constant/ConstantStringTypeTest.php
index ae918cb9a5..3845352fd6 100644
--- a/tests/PHPStan/Type/Constant/ConstantStringTypeTest.php
+++ b/tests/PHPStan/Type/Constant/ConstantStringTypeTest.php
@@ -155,12 +155,12 @@ public function testGeneralize(): void
 		$this->assertSame('literal-string', (new ConstantStringType(''))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
 		$this->assertSame('literal-string&lowercase-string&non-falsy-string', (new ConstantStringType('a'))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
 		$this->assertSame('literal-string&lowercase-string&non-empty-string&numeric-string', (new ConstantStringType('0'))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
-		$this->assertSame('literal-string&non-falsy-string&numeric-string', (new ConstantStringType('1.123'))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
-		$this->assertSame('literal-string&non-falsy-string', (new ConstantStringType('    1       1   '))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
-		$this->assertSame('literal-string&non-falsy-string&numeric-string', (new ConstantStringType('+1'))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
-		$this->assertSame('literal-string&non-falsy-string', (new ConstantStringType('+1+1'))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
-		$this->assertSame('literal-string&non-falsy-string&numeric-string', (new ConstantStringType('1e9'))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
-		$this->assertSame('literal-string&non-falsy-string', (new ConstantStringType('1e91e9'))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
+		$this->assertSame('literal-string&lowercase-string&non-falsy-string&numeric-string', (new ConstantStringType('1.123'))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
+		$this->assertSame('literal-string&lowercase-string&non-falsy-string', (new ConstantStringType('    1       1   '))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
+		$this->assertSame('literal-string&lowercase-string&non-falsy-string&numeric-string', (new ConstantStringType('+1'))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
+		$this->assertSame('literal-string&lowercase-string&non-falsy-string', (new ConstantStringType('+1+1'))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
+		$this->assertSame('literal-string&lowercase-string&non-falsy-string&numeric-string', (new ConstantStringType('1e9'))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
+		$this->assertSame('literal-string&lowercase-string&non-falsy-string', (new ConstantStringType('1e91e9'))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));
 		$this->assertSame('string', (new ConstantStringType(''))->generalize(GeneralizePrecision::lessSpecific())->describe(VerbosityLevel::precise()));
 		$this->assertSame('string', (new ConstantStringType('a'))->generalize(GeneralizePrecision::lessSpecific())->describe(VerbosityLevel::precise()));
 		$this->assertSame('literal-string&non-falsy-string', (new ConstantStringType(stdClass::class))->generalize(GeneralizePrecision::moreSpecific())->describe(VerbosityLevel::precise()));

From ba3ad199e0bfd0d287b8249c17994f008764ec14 Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Fri, 13 Sep 2024 12:39:28 +0200
Subject: [PATCH 06/26] Fix

---
 src/Type/Accessory/AccessoryLowercaseStringType.php | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/Type/Accessory/AccessoryLowercaseStringType.php b/src/Type/Accessory/AccessoryLowercaseStringType.php
index 0e66c5d021..e15f200c1c 100644
--- a/src/Type/Accessory/AccessoryLowercaseStringType.php
+++ b/src/Type/Accessory/AccessoryLowercaseStringType.php
@@ -81,7 +81,7 @@ public function acceptsWithReason(Type $type, bool $strictTypes): AcceptsResult
 			return $type->isAcceptedWithReasonBy($this, $strictTypes);
 		}
 
-		return new AcceptsResult($type->isLiteralString(), []);
+		return new AcceptsResult($type->isLowercaseString(), []);
 	}
 
 	public function isSuperTypeOf(Type $type): TrinaryLogic
@@ -94,7 +94,7 @@ public function isSuperTypeOf(Type $type): TrinaryLogic
 			return TrinaryLogic::createYes();
 		}
 
-		return $type->isLiteralString();
+		return $type->isLowercaseString();
 	}
 
 	public function isSubTypeOf(Type $otherType): TrinaryLogic
@@ -103,7 +103,7 @@ public function isSubTypeOf(Type $otherType): TrinaryLogic
 			return $otherType->isSuperTypeOf($this);
 		}
 
-		return $otherType->isLiteralString()
+		return $otherType->isLowercaseString()
 			->and($otherType instanceof self ? TrinaryLogic::createYes() : TrinaryLogic::createMaybe());
 	}
 
@@ -148,7 +148,7 @@ public function getOffsetValueType(Type $offsetType): Type
 			return new ErrorType();
 		}
 
-		return new StringType();
+		return new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]);
 	}
 
 	public function setOffsetValueType(?Type $offsetType, Type $valueType, bool $unionValues = true): Type

From 9f303b02692df99a4c4131da2c176e10b4871f77 Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Fri, 13 Sep 2024 13:18:28 +0200
Subject: [PATCH 07/26] Fix

---
 phpstan-baseline.neon                                |  5 +++++
 src/Type/Php/StrCaseFunctionsReturnTypeExtension.php | 12 ++++++------
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/phpstan-baseline.neon b/phpstan-baseline.neon
index 79f1b546ea..e5f34c65a2 100644
--- a/phpstan-baseline.neon
+++ b/phpstan-baseline.neon
@@ -716,6 +716,11 @@ parameters:
 			count: 1
 			path: src/Type/Accessory/AccessoryNumericStringType.php
 
+		-
+			message: "#^Doing instanceof PHPStan\\\\Type\\\\IntersectionType is error\\-prone and deprecated\\.$#"
+			count: 1
+			path: src/Type/Accessory/AccessoryLowercaseStringType.php
+
 		-
 			message: "#^Doing instanceof PHPStan\\\\Type\\\\IntersectionType is error\\-prone and deprecated\\.$#"
 			count: 1
diff --git a/src/Type/Php/StrCaseFunctionsReturnTypeExtension.php b/src/Type/Php/StrCaseFunctionsReturnTypeExtension.php
index 376080e3ef..f44f8789aa 100644
--- a/src/Type/Php/StrCaseFunctionsReturnTypeExtension.php
+++ b/src/Type/Php/StrCaseFunctionsReturnTypeExtension.php
@@ -75,13 +75,13 @@ public function getTypeFromFunctionCall(
 			if (count($modes) > 0) {
 				$forceLowercase = count(array_diff($modes, [
 						MB_CASE_LOWER,
-						MB_CASE_LOWER_SIMPLE,
+						5, // MB_CASE_LOWER_SIMPLE
 					])) === 0;
 				$keepLowercase = count(array_diff($modes, [
 						MB_CASE_LOWER,
-						MB_CASE_LOWER_SIMPLE,
-						MB_CASE_FOLD,
-						MB_CASE_FOLD_SIMPLE,
+						5, // MB_CASE_LOWER_SIMPLE
+						3, // MB_CASE_FOLD,
+						7, // MB_CASE_FOLD_SIMPLE
 					])) === 0;
 			}
 		} elseif (in_array($fnName, ['ucwords', 'mb_convert_kana'], true)) {
@@ -91,9 +91,9 @@ public function getTypeFromFunctionCall(
 			} else {
 				$modes = $fnName === 'mb_convert_kana' ? ['KV'] : [" \t\r\n\f\v"];
 			}
-		} elseif (in_array($fnName, ['strtolower', 'mb_strtolower'])) {
+		} elseif (in_array($fnName, ['strtolower', 'mb_strtolower'], true)) {
 			$forceLowercase = true;
-		} elseif (in_array($fnName, ['lcfirst', 'mb_lcfirst'])) {
+		} elseif (in_array($fnName, ['lcfirst', 'mb_lcfirst'], true)) {
 			$keepLowercase = true;
 		}
 

From 1d1627b75a14cb7d1c569eaf3d98386b0ecaea06 Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Fri, 13 Sep 2024 13:27:33 +0200
Subject: [PATCH 08/26] Fix

---
 src/Php/PhpVersion.php                            |  5 +++++
 src/Type/Php/SubstrDynamicReturnTypeExtension.php | 14 ++++++++++++++
 2 files changed, 19 insertions(+)

diff --git a/src/Php/PhpVersion.php b/src/Php/PhpVersion.php
index 4eae1e59f9..b275c464eb 100644
--- a/src/Php/PhpVersion.php
+++ b/src/Php/PhpVersion.php
@@ -348,4 +348,9 @@ public function deprecatesImplicitlyNullableParameterTypes(): bool
 		return $this->versionId >= 80400;
 	}
 
+	public function substrReturnFalseInsteadOfEmptyString(): bool
+	{
+		return $this->versionId < 80000;
+	}
+
 }
diff --git a/src/Type/Php/SubstrDynamicReturnTypeExtension.php b/src/Type/Php/SubstrDynamicReturnTypeExtension.php
index 5edc3f8df4..0a25484f59 100644
--- a/src/Type/Php/SubstrDynamicReturnTypeExtension.php
+++ b/src/Type/Php/SubstrDynamicReturnTypeExtension.php
@@ -4,6 +4,7 @@
 
 use PhpParser\Node\Expr\FuncCall;
 use PHPStan\Analyser\Scope;
+use PHPStan\Php\PhpVersion;
 use PHPStan\Reflection\FunctionReflection;
 use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
@@ -26,6 +27,10 @@
 final class SubstrDynamicReturnTypeExtension implements DynamicFunctionReturnTypeExtension
 {
 
+	public function __construct(private PhpVersion $phpVersion)
+	{
+	}
+
 	public function isFunctionSupported(FunctionReflection $functionReflection): bool
 	{
 		return in_array($functionReflection->getName(), ['substr', 'mb_substr'], true);
@@ -90,10 +95,12 @@ public function getTypeFromFunctionCall(
 		}
 
 		$accessoryTypes = [];
+		$isNotEmpty = false;
 		if ($string->isLowercaseString()->yes()) {
 			$accessoryTypes[] = new AccessoryLowercaseStringType();
 		}
 		if ($string->isNonEmptyString()->yes() && ($negativeOffset || $zeroOffset && $positiveLength)) {
+			$isNotEmpty = true;
 			if ($string->isNonFalsyString()->yes() && !$maybeOneLength) {
 				$accessoryTypes[] = new AccessoryNonFalsyStringType();
 			} else {
@@ -103,6 +110,13 @@ public function getTypeFromFunctionCall(
 		if (count($accessoryTypes) > 0) {
 			$accessoryTypes[] = new StringType();
 
+			if (!$isNotEmpty && $this->phpVersion->substrReturnFalseInsteadOfEmptyString()) {
+				return TypeCombinator::union(
+					new ConstantBooleanType(false),
+					new IntersectionType($accessoryTypes)
+				);
+			}
+
 			return new IntersectionType($accessoryTypes);
 		}
 

From 1f540aa1f1e64bb50a78c6ebb59a9a7999a4f477 Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Fri, 13 Sep 2024 14:54:12 +0200
Subject: [PATCH 09/26] Fix cs

---
 src/Type/Constant/ConstantStringType.php       |  1 +
 .../StrCaseFunctionsReturnTypeExtension.php    | 18 ++++++++++--------
 .../Php/SubstrDynamicReturnTypeExtension.php   |  2 +-
 3 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/src/Type/Constant/ConstantStringType.php b/src/Type/Constant/ConstantStringType.php
index 6468944221..382911e69d 100644
--- a/src/Type/Constant/ConstantStringType.php
+++ b/src/Type/Constant/ConstantStringType.php
@@ -49,6 +49,7 @@
 use function is_numeric;
 use function key;
 use function strlen;
+use function strtolower;
 use function substr;
 use function substr_count;
 
diff --git a/src/Type/Php/StrCaseFunctionsReturnTypeExtension.php b/src/Type/Php/StrCaseFunctionsReturnTypeExtension.php
index f44f8789aa..149caff081 100644
--- a/src/Type/Php/StrCaseFunctionsReturnTypeExtension.php
+++ b/src/Type/Php/StrCaseFunctionsReturnTypeExtension.php
@@ -16,11 +16,13 @@
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeCombinator;
 use PHPStan\Type\TypeUtils;
+use function array_diff;
 use function array_map;
 use function count;
 use function in_array;
 use function is_callable;
 use function mb_check_encoding;
+use const MB_CASE_LOWER;
 
 final class StrCaseFunctionsReturnTypeExtension implements DynamicFunctionReturnTypeExtension
 {
@@ -74,15 +76,15 @@ public function getTypeFromFunctionCall(
 			$modes = array_map(static fn ($mode) => $mode->getValue(), TypeUtils::getConstantIntegers($modeType));
 			if (count($modes) > 0) {
 				$forceLowercase = count(array_diff($modes, [
-						MB_CASE_LOWER,
-						5, // MB_CASE_LOWER_SIMPLE
-					])) === 0;
+					MB_CASE_LOWER,
+					5, // MB_CASE_LOWER_SIMPLE
+				])) === 0;
 				$keepLowercase = count(array_diff($modes, [
-						MB_CASE_LOWER,
-						5, // MB_CASE_LOWER_SIMPLE
-						3, // MB_CASE_FOLD,
-						7, // MB_CASE_FOLD_SIMPLE
-					])) === 0;
+					MB_CASE_LOWER,
+					5, // MB_CASE_LOWER_SIMPLE
+					3, // MB_CASE_FOLD,
+					7, // MB_CASE_FOLD_SIMPLE
+				])) === 0;
 			}
 		} elseif (in_array($fnName, ['ucwords', 'mb_convert_kana'], true)) {
 			if (count($args) >= 2) {
diff --git a/src/Type/Php/SubstrDynamicReturnTypeExtension.php b/src/Type/Php/SubstrDynamicReturnTypeExtension.php
index 0a25484f59..4364f2374f 100644
--- a/src/Type/Php/SubstrDynamicReturnTypeExtension.php
+++ b/src/Type/Php/SubstrDynamicReturnTypeExtension.php
@@ -113,7 +113,7 @@ public function getTypeFromFunctionCall(
 			if (!$isNotEmpty && $this->phpVersion->substrReturnFalseInsteadOfEmptyString()) {
 				return TypeCombinator::union(
 					new ConstantBooleanType(false),
-					new IntersectionType($accessoryTypes)
+					new IntersectionType($accessoryTypes),
 				);
 			}
 

From befce48ff1be558ddbd6c9da609c7fa42702c36f Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Fri, 13 Sep 2024 15:51:14 +0200
Subject: [PATCH 10/26] Fix baseline

---
 phpstan-baseline.neon | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/phpstan-baseline.neon b/phpstan-baseline.neon
index e5f34c65a2..b7c18db8d9 100644
--- a/phpstan-baseline.neon
+++ b/phpstan-baseline.neon
@@ -691,6 +691,11 @@ parameters:
 			count: 1
 			path: src/Type/Accessory/AccessoryLiteralStringType.php
 
+		-
+			message: "#^Doing instanceof PHPStan\\\\Type\\\\IntersectionType is error\\-prone and deprecated\\.$#"
+			count: 1
+			path: src/Type/Accessory/AccessoryLowercaseStringType.php
+
 		-
 			message: "#^Doing instanceof PHPStan\\\\Type\\\\Constant\\\\ConstantStringType is error\\-prone and deprecated\\. Use Type\\:\\:getConstantStrings\\(\\) instead\\.$#"
 			count: 1
@@ -716,11 +721,6 @@ parameters:
 			count: 1
 			path: src/Type/Accessory/AccessoryNumericStringType.php
 
-		-
-			message: "#^Doing instanceof PHPStan\\\\Type\\\\IntersectionType is error\\-prone and deprecated\\.$#"
-			count: 1
-			path: src/Type/Accessory/AccessoryLowercaseStringType.php
-
 		-
 			message: "#^Doing instanceof PHPStan\\\\Type\\\\IntersectionType is error\\-prone and deprecated\\.$#"
 			count: 1

From 31a526034b1142864480056474f72d7112cd7815 Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Fri, 13 Sep 2024 15:55:07 +0200
Subject: [PATCH 11/26] Fix tests

---
 tests/PHPStan/Analyser/NodeScopeResolverTest.php   |  6 ++++++
 tests/PHPStan/Analyser/data/explode-php74.php      | 14 ++++++++++++++
 tests/PHPStan/Analyser/data/explode-php80.php      | 14 ++++++++++++++
 .../Analyser/nsrt/lowercase-string-implode.php     | 14 --------------
 4 files changed, 34 insertions(+), 14 deletions(-)
 create mode 100644 tests/PHPStan/Analyser/data/explode-php74.php
 create mode 100644 tests/PHPStan/Analyser/data/explode-php80.php

diff --git a/tests/PHPStan/Analyser/NodeScopeResolverTest.php b/tests/PHPStan/Analyser/NodeScopeResolverTest.php
index a4bfe75364..2816b5ce52 100644
--- a/tests/PHPStan/Analyser/NodeScopeResolverTest.php
+++ b/tests/PHPStan/Analyser/NodeScopeResolverTest.php
@@ -51,6 +51,12 @@ private static function findTestFiles(): iterable
 
 		yield __DIR__ . '/../Rules/Methods/data/bug-6856.php';
 
+		if (PHP_VERSION_ID < 80000) {
+			yield __DIR__ . '/data/explode-php74.php';
+		} else {
+			yield __DIR__ . '/data/explode-php80.php';
+		}
+
 		if (PHP_VERSION_ID >= 80000) {
 			yield __DIR__ . '/../Reflection/data/unionTypes.php';
 			yield __DIR__ . '/../Reflection/data/mixedType.php';
diff --git a/tests/PHPStan/Analyser/data/explode-php74.php b/tests/PHPStan/Analyser/data/explode-php74.php
new file mode 100644
index 0000000000..efdd404424
--- /dev/null
+++ b/tests/PHPStan/Analyser/data/explode-php74.php
@@ -0,0 +1,14 @@
+<?php
+
+namespace ExplodePhp74;
+
+use function PHPStan\Testing\assertType;
+
+class ExplodingStrings
+{
+	public function doFoo(string $s): void
+	{
+		assertType('non-empty-list<lowercase-string>|false', explode($s, 'foo'));
+		assertType('non-empty-list<string>|false', explode($s, 'FOO'));
+	}
+}
diff --git a/tests/PHPStan/Analyser/data/explode-php80.php b/tests/PHPStan/Analyser/data/explode-php80.php
new file mode 100644
index 0000000000..4fa4539356
--- /dev/null
+++ b/tests/PHPStan/Analyser/data/explode-php80.php
@@ -0,0 +1,14 @@
+<?php
+
+namespace ExplodePhp80;
+
+use function PHPStan\Testing\assertType;
+
+class ExplodingStrings
+{
+	public function doFoo(string $s): void
+	{
+		assertType('non-empty-list<lowercase-string>', explode($s, 'foo'));
+		assertType('non-empty-list<string>', explode($s, 'FOO'));
+	}
+}
diff --git a/tests/PHPStan/Analyser/nsrt/lowercase-string-implode.php b/tests/PHPStan/Analyser/nsrt/lowercase-string-implode.php
index 19fc961f1f..3aff9f3389 100644
--- a/tests/PHPStan/Analyser/nsrt/lowercase-string-implode.php
+++ b/tests/PHPStan/Analyser/nsrt/lowercase-string-implode.php
@@ -2,21 +2,7 @@
 
 namespace LowercaseStringImplode;
 
-use function htmlspecialchars;
-use function lcfirst;
 use function PHPStan\Testing\assertType;
-use function strtolower;
-use function strtoupper;
-use function ucfirst;
-
-class ExplodingStrings
-{
-	public function doFoo(string $s): void
-	{
-		assertType('non-empty-list<lowercase-string>', explode($s, 'foo'));
-		assertType('non-empty-list<string>', explode($s, 'FOO'));
-	}
-}
 
 class ImplodingStrings
 {

From 81e8090358ab66bc1e6d2d3c99981b423a449070 Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Fri, 13 Sep 2024 22:52:13 +0200
Subject: [PATCH 12/26] Add support for Concat operator

---
 src/Reflection/InitializerExprTypeResolver.php              | 4 ++++
 tests/PHPStan/Analyser/nsrt/constant-string-unions.php      | 6 +++---
 .../Analyser/nsrt/foreach-partially-non-iterable.php        | 2 +-
 .../Rules/Functions/CallToFunctionParametersRuleTest.php    | 2 +-
 4 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/Reflection/InitializerExprTypeResolver.php b/src/Reflection/InitializerExprTypeResolver.php
index 1eec9736d1..8b015c91ab 100644
--- a/src/Reflection/InitializerExprTypeResolver.php
+++ b/src/Reflection/InitializerExprTypeResolver.php
@@ -27,6 +27,7 @@
 use PHPStan\ShouldNotHappenException;
 use PHPStan\Type\Accessory\AccessoryArrayListType;
 use PHPStan\Type\Accessory\AccessoryLiteralStringType;
+use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
 use PHPStan\Type\Accessory\AccessoryNonFalsyStringType;
 use PHPStan\Type\Accessory\AccessoryNumericStringType;
@@ -478,6 +479,9 @@ public function resolveConcatType(Type $left, Type $right): Type
 		if ($leftStringType->isLiteralString()->and($rightStringType->isLiteralString())->yes()) {
 			$accessoryTypes[] = new AccessoryLiteralStringType();
 		}
+		if ($leftStringType->isLowercaseString()->and($rightStringType->isLowercaseString())->yes()) {
+			$accessoryTypes[] = new AccessoryLowercaseStringType();
+		}
 
 		$leftNumericStringNonEmpty = TypeCombinator::remove($leftStringType, new ConstantStringType(''));
 		if ($leftNumericStringNonEmpty->isNumericString()->yes()) {
diff --git a/tests/PHPStan/Analyser/nsrt/constant-string-unions.php b/tests/PHPStan/Analyser/nsrt/constant-string-unions.php
index 06881808e8..b97b117179 100644
--- a/tests/PHPStan/Analyser/nsrt/constant-string-unions.php
+++ b/tests/PHPStan/Analyser/nsrt/constant-string-unions.php
@@ -72,7 +72,7 @@ public function testLimit(string $s15, string $s16, string $s17) {
 		// union should contain 32 elements
 		assertType("'1'|'10'|'10a'|'11'|'11a'|'12'|'12a'|'13'|'13a'|'14'|'14a'|'15'|'15a'|'16'|'16a'|'1a'|'2'|'2a'|'3'|'3a'|'4'|'4a'|'5'|'5a'|'6'|'6a'|'7'|'7a'|'8'|'8a'|'9'|'9a'", $s16);
 		// fallback to the more general form
-		assertType("literal-string&non-falsy-string", $s17);
+		assertType("literal-string&lowercase-string&non-falsy-string", $s17);
 		$left = rand() ? 'a' : 'b';
 		$right = rand() ? 'x' : 'y';
 		$left .= $right;
@@ -80,7 +80,7 @@ public function testLimit(string $s15, string $s16, string $s17) {
 		$left .= $right;
 		assertType("'axxx'|'axxy'|'axyx'|'axyy'|'ayxx'|'ayxy'|'ayyx'|'ayyy'|'bxxx'|'bxxy'|'bxyx'|'bxyy'|'byxx'|'byxy'|'byyx'|'byyy'", $left);
 		$left .= $right;
-		assertType("literal-string&non-falsy-string", $left);
+		assertType("literal-string&lowercase-string&non-falsy-string", $left);
 
 		$left = rand() ? 'a' : 'b';
 		$right = rand() ? 'x' : 'y';
@@ -89,7 +89,7 @@ public function testLimit(string $s15, string $s16, string $s17) {
 		$left = "{$left}{$right}";
 		assertType("'axxx'|'axxy'|'axyx'|'axyy'|'ayxx'|'ayxy'|'ayyx'|'ayyy'|'bxxx'|'bxxy'|'bxyx'|'bxyy'|'byxx'|'byxy'|'byyx'|'byyy'", $left);
 		$left = "{$left}{$right}";
-		assertType("literal-string&non-falsy-string", $left);
+		assertType("literal-string&lowercase-string&non-falsy-string", $left);
 	}
 
 	/**
diff --git a/tests/PHPStan/Analyser/nsrt/foreach-partially-non-iterable.php b/tests/PHPStan/Analyser/nsrt/foreach-partially-non-iterable.php
index ad8e375e58..a1d7279252 100644
--- a/tests/PHPStan/Analyser/nsrt/foreach-partially-non-iterable.php
+++ b/tests/PHPStan/Analyser/nsrt/foreach-partially-non-iterable.php
@@ -29,7 +29,7 @@ public function sayHello(\stdClass $s): void
 		foreach ($s as $k => $v) {
 			$a .= 'test';
 		}
-		assertType('(literal-string&non-falsy-string)|null', $a);
+		assertType('(literal-string&lowercase-string&non-falsy-string)|null', $a);
 	}
 
 }
diff --git a/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php b/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php
index a47624e8e8..4b00fb720e 100644
--- a/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php
+++ b/tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php
@@ -636,7 +636,7 @@ public function testArrayUdiffCallback(): void
 				6,
 			],
 			[
-				'Parameter #3 $data_comp_func of function array_udiff expects callable(1|2|3|4|5|6, 1|2|3|4|5|6): int, Closure(int, int): (literal-string&non-falsy-string&numeric-string) given.',
+				'Parameter #3 $data_comp_func of function array_udiff expects callable(1|2|3|4|5|6, 1|2|3|4|5|6): int, Closure(int, int): (literal-string&lowercase-string&non-falsy-string&numeric-string) given.',
 				14,
 			],
 			[

From 8fbe212df6435752e67ccf074764f5f096e32b1a Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Sat, 14 Sep 2024 09:53:15 +0200
Subject: [PATCH 13/26] Add tests

---
 tests/PHPStan/Analyser/nsrt/more-types.php    |  8 +++-
 ...rictComparisonOfDifferentTypesRuleTest.php | 48 +++++++++++++++++++
 .../Comparison/data/lowercase-string.php      | 31 ++++++++++++
 3 files changed, 86 insertions(+), 1 deletion(-)
 create mode 100644 tests/PHPStan/Rules/Comparison/data/lowercase-string.php

diff --git a/tests/PHPStan/Analyser/nsrt/more-types.php b/tests/PHPStan/Analyser/nsrt/more-types.php
index 70dc86d3d9..9c3296c3d8 100644
--- a/tests/PHPStan/Analyser/nsrt/more-types.php
+++ b/tests/PHPStan/Analyser/nsrt/more-types.php
@@ -17,6 +17,8 @@ class Foo
 	 * @param non-empty-scalar $nonEmptyScalar
 	 * @param empty-scalar $emptyScalar
 	 * @param non-empty-mixed $nonEmptyMixed
+	 * @param lowercase-string $lowercaseString
+	 * @param non-empty-lowercase-string $nonEmptyLowercaseString
 	 */
 	public function doFoo(
 		$pureCallable,
@@ -27,7 +29,9 @@ public function doFoo(
 		$nonEmptyLiteralString,
 		$nonEmptyScalar,
 		$emptyScalar,
-		$nonEmptyMixed
+		$nonEmptyMixed,
+		$lowercaseString,
+		$nonEmptyLowercaseString,
 	): void
 	{
 		assertType('pure-callable(): mixed', $pureCallable);
@@ -39,6 +43,8 @@ public function doFoo(
 		assertType('float|int<min, -1>|int<1, max>|non-falsy-string|true', $nonEmptyScalar);
 		assertType("0|0.0|''|'0'|false", $emptyScalar);
 		assertType("mixed~(0|0.0|''|'0'|array{}|false|null)", $nonEmptyMixed);
+		assertType('lowercase-string', $lowercaseString);
+		assertType('lowercase-string&non-empty-string', $nonEmptyLowercaseString);
 	}
 
 }
diff --git a/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php b/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php
index fe9b8fa079..33e7465bf2 100644
--- a/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php
+++ b/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php
@@ -1057,6 +1057,54 @@ public function testBug10697(): void
 		$this->analyse([__DIR__ . '/data/bug-10697.php'], []);
 	}
 
+	public function testLowercaseString(): void
+	{
+		$errors = [
+			[
+				"Strict comparison using === between lowercase-string and 'AB' will always evaluate to false.",
+				10,
+				'Because the type is coming from a PHPDoc, you can turn off this check by setting <fg=cyan>treatPhpDocTypesAsCertain: false</> in your <fg=cyan>%configurationFile%</>.',
+			],
+			[
+				"Strict comparison using === between 'AB' and lowercase-string will always evaluate to false.",
+				11,
+				'Because the type is coming from a PHPDoc, you can turn off this check by setting <fg=cyan>treatPhpDocTypesAsCertain: false</> in your <fg=cyan>%configurationFile%</>.',
+			],
+			[
+				"Strict comparison using !== between 'AB' and lowercase-string will always evaluate to true.",
+				12,
+				'Because the type is coming from a PHPDoc, you can turn off this check by setting <fg=cyan>treatPhpDocTypesAsCertain: false</> in your <fg=cyan>%configurationFile%</>.',
+			],
+			[
+				"Strict comparison using === between lowercase-string and 'aBc' will always evaluate to false.",
+				15,
+				'Because the type is coming from a PHPDoc, you can turn off this check by setting <fg=cyan>treatPhpDocTypesAsCertain: false</> in your <fg=cyan>%configurationFile%</>.',
+			],
+			[
+				"Strict comparison using !== between lowercase-string and 'aBc' will always evaluate to true.",
+				16,
+				'Because the type is coming from a PHPDoc, you can turn off this check by setting <fg=cyan>treatPhpDocTypesAsCertain: false</> in your <fg=cyan>%configurationFile%</>.',
+			],
+		];
+
+		if (PHP_VERSION_ID < 80000) {
+			$errors[] = [
+				"Strict comparison using === between lowercase-string|false and 'AB' will always evaluate to false.",
+				28,
+				'Because the type is coming from a PHPDoc, you can turn off this check by setting <fg=cyan>treatPhpDocTypesAsCertain: false</> in your <fg=cyan>%configurationFile%</>.',
+			];
+		} else {
+			$errors[] = [
+				"Strict comparison using === between lowercase-string and 'AB' will always evaluate to false.",
+				28,
+				'Because the type is coming from a PHPDoc, you can turn off this check by setting <fg=cyan>treatPhpDocTypesAsCertain: false</> in your <fg=cyan>%configurationFile%</>.',
+			];
+		}
+
+		$this->checkAlwaysTrueStrictComparison = true;
+		$this->analyse([__DIR__ . '/data/lowercase-string.php'], $errors);
+	}
+
 	public function testBug10493(): void
 	{
 		$this->checkAlwaysTrueStrictComparison = true;
diff --git a/tests/PHPStan/Rules/Comparison/data/lowercase-string.php b/tests/PHPStan/Rules/Comparison/data/lowercase-string.php
new file mode 100644
index 0000000000..772939626a
--- /dev/null
+++ b/tests/PHPStan/Rules/Comparison/data/lowercase-string.php
@@ -0,0 +1,31 @@
+<?php
+
+namespace LowercaseString;
+
+class Foo
+{
+
+	/** @param lowercase-string $s */
+	function doFoo($s) {
+		if ($s === 'AB') {}
+		if ('AB' === $s) {}
+		if ('AB' !== $s) {}
+		if ($s === 'ab') {}
+		if ($s !== 'ab') {}
+		if ($s === 'aBc') {}
+		if ($s !== 'aBc') {}
+		if ($s === '01') {}
+		if ($s === '1e2') {}
+		if ($s === MyClass::myConst) {}
+		if ($s === A_GLOBAL_CONST) {}
+		if (doFoo('hi') === 'AB') {}
+	}
+
+	/** @param lowercase-string $s */
+	function doFoo2($s, int $x, int $y) {
+		$part = substr($s, $x, $y);
+
+		if ($part === 'AB') {}
+    }
+
+}

From 8c4b0b9f0fcd5fc38fab8d0370820af340a5c1d8 Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Sun, 15 Sep 2024 19:57:23 +0200
Subject: [PATCH 14/26] Wip

---
 .../AccessoryLowercaseStringType.php          |  3 -
 .../Rules/Methods/CallMethodsRuleTest.php     | 23 ++++++++
 .../Rules/Methods/data/lowercase-string.php   | 33 +++++++++++
 tests/PHPStan/Type/TypeCombinatorTest.php     | 58 +++++++++++++++++++
 4 files changed, 114 insertions(+), 3 deletions(-)
 create mode 100644 tests/PHPStan/Rules/Methods/data/lowercase-string.php

diff --git a/src/Type/Accessory/AccessoryLowercaseStringType.php b/src/Type/Accessory/AccessoryLowercaseStringType.php
index e15f200c1c..2b1519a103 100644
--- a/src/Type/Accessory/AccessoryLowercaseStringType.php
+++ b/src/Type/Accessory/AccessoryLowercaseStringType.php
@@ -74,9 +74,6 @@ public function accepts(Type $type, bool $strictTypes): TrinaryLogic
 
 	public function acceptsWithReason(Type $type, bool $strictTypes): AcceptsResult
 	{
-		if ($type instanceof MixedType) {
-			return AcceptsResult::createNo();
-		}
 		if ($type instanceof CompoundType) {
 			return $type->isAcceptedWithReasonBy($this, $strictTypes);
 		}
diff --git a/tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php b/tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php
index 8bb53330d4..93b5b9303e 100644
--- a/tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php
+++ b/tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php
@@ -3354,6 +3354,29 @@ public function testTraitMixin(): void
 		$this->analyse([__DIR__ . '/data/trait-mixin.php'], []);
 	}
 
+	public function testLowercaseString(): void
+	{
+		$this->checkThisOnly = false;
+		$this->checkNullables = true;
+		$this->checkUnionTypes = true;
+		$this->checkExplicitMixed = true;
+
+		$this->analyse([__DIR__ . '/data/lowercase-string.php'], [
+			[
+				'Parameter #1 $s of method LowercaseString\Bar::acceptLowercaseString() expects lowercase-string, \'NotLowerCase\' given.',
+				26,
+			],
+			[
+				'Parameter #1 $s of method LowercaseString\Bar::acceptLowercaseString() expects lowercase-string, string given.',
+				28,
+			],
+			[
+				'Parameter #1 $s of method LowercaseString\Bar::acceptLowercaseString() expects lowercase-string, numeric-string given.',
+				30,
+			],
+		]);
+	}
+
 	public function testBug10159(): void
 	{
 		$this->checkThisOnly = false;
diff --git a/tests/PHPStan/Rules/Methods/data/lowercase-string.php b/tests/PHPStan/Rules/Methods/data/lowercase-string.php
new file mode 100644
index 0000000000..40c475e9e5
--- /dev/null
+++ b/tests/PHPStan/Rules/Methods/data/lowercase-string.php
@@ -0,0 +1,33 @@
+<?php
+
+namespace LowercaseString;
+
+class Bar
+{
+	/** @param lowercase-string $s */
+	public function acceptLowercaseString(string $s): void
+	{
+	}
+
+	/**
+	 * @param string $string
+	 * @param lowercase-string $lowercaseString
+	 * @param numeric-string $numericString
+	 * @param non-empty-lowercase-string $nonEmptyLowercaseString
+	 *
+	 * @return void
+	 */
+	public function test(
+		string $string,
+		string $lowercaseString,
+		string $numericString,
+		string $nonEmptyLowercaseString
+	): void {
+		$this->acceptLowercaseString('NotLowerCase');
+		$this->acceptLowercaseString('lowercase');
+		$this->acceptLowercaseString($string);
+		$this->acceptLowercaseString($lowercaseString);
+		$this->acceptLowercaseString($numericString);
+		$this->acceptLowercaseString($nonEmptyLowercaseString);
+	}
+}
diff --git a/tests/PHPStan/Type/TypeCombinatorTest.php b/tests/PHPStan/Type/TypeCombinatorTest.php
index 95e11da973..5e04a84612 100644
--- a/tests/PHPStan/Type/TypeCombinatorTest.php
+++ b/tests/PHPStan/Type/TypeCombinatorTest.php
@@ -19,6 +19,7 @@
 use PHPStan\Testing\PHPStanTestCase;
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\Accessory\AccessoryLiteralStringType;
+use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
 use PHPStan\Type\Accessory\AccessoryNonFalsyStringType;
 use PHPStan\Type\Accessory\AccessoryNumericStringType;
@@ -2591,6 +2592,46 @@ public function dataUnion(): iterable
 			IntersectionType::class,
 			'array&hasOffsetValue(\'thing\', mixed)',
 		];
+		yield [
+			[
+				new StringType(),
+				new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+			],
+			StringType::class,
+			'string',
+		];
+		yield [
+			[
+				new IntersectionType([new StringType(), new AccessoryNumericStringType()]),
+				new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+			],
+			UnionType::class,
+			'lowercase-string|numeric-string',
+		];
+		yield [
+			[
+				new IntersectionType([new StringType(), new AccessoryNonFalsyStringType()]),
+				new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+			],
+			UnionType::class,
+			'lowercase-string|non-falsy-string',
+		];
+		yield [
+			[
+				new IntersectionType([new StringType(), new AccessoryNonEmptyStringType()]),
+				new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+			],
+			UnionType::class,
+			'lowercase-string|non-empty-string',
+		];
+		yield [
+			[
+				new IntersectionType([new StringType(), new AccessoryLiteralStringType()]),
+				new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+			],
+			UnionType::class,
+			'lowercase-string|literal-string',
+		];
 	}
 
 	/**
@@ -4325,6 +4366,23 @@ public function dataIntersect(): iterable
 			NeverType::class,
 			'*NEVER*=implicit',
 		];
+
+		yield [
+			[
+				new ConstantStringType('FOO'),
+				new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+			],
+			NeverType::class,
+			'*NEVER*=implicit',
+		];
+		yield [
+			[
+				new ConstantStringType('foo'),
+				new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+			],
+			ConstantStringType::class,
+			'\'foo\'',
+		];
 	}
 
 	/**

From f249cff1f486bb2a5d09b499649672d3e0052a11 Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Sun, 15 Sep 2024 22:19:44 +0200
Subject: [PATCH 15/26] Add TypeCombinator tests

---
 tests/PHPStan/Type/TypeCombinatorTest.php | 120 ++++++++++++++--------
 1 file changed, 80 insertions(+), 40 deletions(-)

diff --git a/tests/PHPStan/Type/TypeCombinatorTest.php b/tests/PHPStan/Type/TypeCombinatorTest.php
index 5e04a84612..55dc30542b 100644
--- a/tests/PHPStan/Type/TypeCombinatorTest.php
+++ b/tests/PHPStan/Type/TypeCombinatorTest.php
@@ -1969,6 +1969,46 @@ public function dataUnion(): iterable
 				UnionType::class,
 				'literal-string|numeric-string',
 			],
+			[
+				[
+					new StringType(),
+					new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+				],
+				StringType::class,
+				'string',
+			],
+			[
+				[
+					new IntersectionType([new StringType(), new AccessoryNumericStringType()]),
+					new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+				],
+				UnionType::class,
+				'lowercase-string|numeric-string',
+			],
+			[
+				[
+					new IntersectionType([new StringType(), new AccessoryNonFalsyStringType()]),
+					new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+				],
+				UnionType::class,
+				'lowercase-string|non-falsy-string',
+			],
+			[
+				[
+					new IntersectionType([new StringType(), new AccessoryNonEmptyStringType()]),
+					new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+				],
+				UnionType::class,
+				'lowercase-string|non-empty-string',
+			],
+			[
+				[
+					new IntersectionType([new StringType(), new AccessoryLiteralStringType()]),
+					new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+				],
+				UnionType::class,
+				'literal-string|lowercase-string',
+			],
 			[
 				[
 					TemplateTypeFactory::create(
@@ -2592,46 +2632,6 @@ public function dataUnion(): iterable
 			IntersectionType::class,
 			'array&hasOffsetValue(\'thing\', mixed)',
 		];
-		yield [
-			[
-				new StringType(),
-				new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
-			],
-			StringType::class,
-			'string',
-		];
-		yield [
-			[
-				new IntersectionType([new StringType(), new AccessoryNumericStringType()]),
-				new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
-			],
-			UnionType::class,
-			'lowercase-string|numeric-string',
-		];
-		yield [
-			[
-				new IntersectionType([new StringType(), new AccessoryNonFalsyStringType()]),
-				new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
-			],
-			UnionType::class,
-			'lowercase-string|non-falsy-string',
-		];
-		yield [
-			[
-				new IntersectionType([new StringType(), new AccessoryNonEmptyStringType()]),
-				new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
-			],
-			UnionType::class,
-			'lowercase-string|non-empty-string',
-		];
-		yield [
-			[
-				new IntersectionType([new StringType(), new AccessoryLiteralStringType()]),
-				new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
-			],
-			UnionType::class,
-			'lowercase-string|literal-string',
-		];
 	}
 
 	/**
@@ -3894,6 +3894,46 @@ public function dataIntersect(): iterable
 				NeverType::class,
 				'*NEVER*=implicit',
 			],
+			[
+				[
+					new StringType(),
+					new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+				],
+				IntersectionType::class,
+				'lowercase-string',
+			],
+			[
+				[
+					new IntersectionType([new StringType(), new AccessoryNumericStringType()]),
+					new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+				],
+				IntersectionType::class,
+				'lowercase-string&numeric-string',
+			],
+			[
+				[
+					new IntersectionType([new StringType(), new AccessoryNonFalsyStringType()]),
+					new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+				],
+				IntersectionType::class,
+				'lowercase-string&non-falsy-string',
+			],
+			[
+				[
+					new IntersectionType([new StringType(), new AccessoryNonEmptyStringType()]),
+					new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+				],
+				IntersectionType::class,
+				'lowercase-string&non-empty-string',
+			],
+			[
+				[
+					new IntersectionType([new StringType(), new AccessoryLiteralStringType()]),
+					new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+				],
+				IntersectionType::class,
+				'literal-string&lowercase-string',
+			],
 		];
 
 		if (PHP_VERSION_ID < 80100) {

From 343e55b3497b19657821233e5ae4303ef8932274 Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Sun, 15 Sep 2024 22:59:32 +0200
Subject: [PATCH 16/26] WIP

---
 .../AccessoryLowercaseStringType.php          |  1 -
 src/Type/IntersectionType.php                 |  4 +++
 src/Type/VerbosityLevel.php                   |  8 ++++--
 tests/PHPStan/Type/IntersectionTypeTest.php   | 28 +++++++++++++++++++
 4 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/src/Type/Accessory/AccessoryLowercaseStringType.php b/src/Type/Accessory/AccessoryLowercaseStringType.php
index 2b1519a103..195a807dbc 100644
--- a/src/Type/Accessory/AccessoryLowercaseStringType.php
+++ b/src/Type/Accessory/AccessoryLowercaseStringType.php
@@ -17,7 +17,6 @@
 use PHPStan\Type\GeneralizePrecision;
 use PHPStan\Type\IntegerType;
 use PHPStan\Type\IntersectionType;
-use PHPStan\Type\MixedType;
 use PHPStan\Type\ObjectWithoutClassType;
 use PHPStan\Type\StringType;
 use PHPStan\Type\Traits\MaybeCallableTypeTrait;
diff --git a/src/Type/IntersectionType.php b/src/Type/IntersectionType.php
index 49647a52cd..22a4d811e4 100644
--- a/src/Type/IntersectionType.php
+++ b/src/Type/IntersectionType.php
@@ -331,6 +331,10 @@ private function describeItself(VerbosityLevel $level, bool $skipAccessoryTypes)
 				|| $type instanceof AccessoryNonFalsyStringType
 				|| $type instanceof AccessoryLowercaseStringType
 			) {
+				if ($type instanceof AccessoryLowercaseStringType && !$level->isPrecise()) {
+					continue;
+				}
+
 				if ($type instanceof AccessoryNonFalsyStringType) {
 					$nonFalsyStr = true;
 				}
diff --git a/src/Type/VerbosityLevel.php b/src/Type/VerbosityLevel.php
index 086401052f..69a5c2fcd1 100644
--- a/src/Type/VerbosityLevel.php
+++ b/src/Type/VerbosityLevel.php
@@ -87,6 +87,10 @@ public function isPrecise(): bool
 	/** @api */
 	public static function getRecommendedLevelByType(Type $acceptingType, ?Type $acceptedType = null): self
 	{
+		$verboseLevelCallback = static function (Type $acceptingType): VerbosityLevel {
+			return $acceptingType->isLowercaseString()->yes() ? self::precise() : self::value();
+		};
+
 		$moreVerboseCallback = static function (Type $type, callable $traverse) use (&$moreVerbose): Type {
 			if ($type->isCallable()->yes()) {
 				$moreVerbose = true;
@@ -121,7 +125,7 @@ public static function getRecommendedLevelByType(Type $acceptingType, ?Type $acc
 		TypeTraverser::map($acceptingType, $moreVerboseCallback);
 
 		if ($moreVerbose) {
-			return self::value();
+			return $verboseLevelCallback($acceptingType);
 		}
 
 		if ($acceptedType === null) {
@@ -160,7 +164,7 @@ public static function getRecommendedLevelByType(Type $acceptingType, ?Type $acc
 		$moreVerbose = false;
 		TypeTraverser::map($acceptedType, $moreVerboseCallback);
 
-		return $moreVerbose ? self::value() : self::typeOnly();
+		return $moreVerbose ? $verboseLevelCallback($acceptingType) : self::typeOnly();
 	}
 
 	/**
diff --git a/tests/PHPStan/Type/IntersectionTypeTest.php b/tests/PHPStan/Type/IntersectionTypeTest.php
index aae9faa0bd..7c9bcc0722 100644
--- a/tests/PHPStan/Type/IntersectionTypeTest.php
+++ b/tests/PHPStan/Type/IntersectionTypeTest.php
@@ -7,6 +7,7 @@
 use ObjectTypeEnums\FooEnum;
 use PHPStan\Testing\PHPStanTestCase;
 use PHPStan\TrinaryLogic;
+use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\HasOffsetType;
 use PHPStan\Type\Accessory\HasPropertyType;
 use PHPStan\Type\Accessory\NonEmptyArrayType;
@@ -447,4 +448,31 @@ public function testGetEnumCases(
 		}
 	}
 
+	public function dataDescribe(): iterable
+	{
+		yield [
+			new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+			VerbosityLevel::typeOnly(),
+			'string',
+		];
+		yield [
+			new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+			VerbosityLevel::value(),
+			'string',
+		];
+		yield [
+			new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+			VerbosityLevel::precise(),
+			'lowercase-string',
+		];
+	}
+
+	/**
+	 * @dataProvider dataDescribe
+	 */
+	public function testDescribe(IntersectionType $type, VerbosityLevel $verbosityLevel, string $expected): void
+	{
+		static::assertSame($expected, $type->describe($verbosityLevel));
+	}
+
 }

From bd26dd5a6e929d881f78997c880093a02afe39ff Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Mon, 16 Sep 2024 10:26:01 +0200
Subject: [PATCH 17/26] Rework

---
 src/Type/VerbosityLevel.php | 33 ++++++++++++++++-----------------
 1 file changed, 16 insertions(+), 17 deletions(-)

diff --git a/src/Type/VerbosityLevel.php b/src/Type/VerbosityLevel.php
index 69a5c2fcd1..7934506aea 100644
--- a/src/Type/VerbosityLevel.php
+++ b/src/Type/VerbosityLevel.php
@@ -87,17 +87,13 @@ public function isPrecise(): bool
 	/** @api */
 	public static function getRecommendedLevelByType(Type $acceptingType, ?Type $acceptedType = null): self
 	{
-		$verboseLevelCallback = static function (Type $acceptingType): VerbosityLevel {
-			return $acceptingType->isLowercaseString()->yes() ? self::precise() : self::value();
-		};
-
-		$moreVerboseCallback = static function (Type $type, callable $traverse) use (&$moreVerbose): Type {
+		$moreVerboseCallback = static function (Type $type, callable $traverse) use (&$verboseLevel): Type {
 			if ($type->isCallable()->yes()) {
-				$moreVerbose = true;
+				$verboseLevel = self::value();
 				return $type;
 			}
 			if ($type->isConstantValue()->yes() && $type->isNull()->no()) {
-				$moreVerbose = true;
+				$verboseLevel = self::value();
 				return $type;
 			}
 			if (
@@ -106,26 +102,29 @@ public static function getRecommendedLevelByType(Type $acceptingType, ?Type $acc
 				|| $type instanceof AccessoryNonFalsyStringType
 				|| $type instanceof AccessoryLiteralStringType
 				|| $type instanceof AccessoryNumericStringType
-				|| $type instanceof AccessoryLowercaseStringType
 				|| $type instanceof NonEmptyArrayType
 				|| $type instanceof AccessoryArrayListType
 			) {
-				$moreVerbose = true;
+				$verboseLevel = self::value();
+				return $type;
+			}
+			if ($type instanceof AccessoryLowercaseStringType) {
+				$verboseLevel = self::precise();
 				return $type;
 			}
 			if ($type instanceof IntegerRangeType) {
-				$moreVerbose = true;
+				$verboseLevel = self::value();
 				return $type;
 			}
 			return $traverse($type);
 		};
 
-		/** @var bool $moreVerbose */
-		$moreVerbose = false;
+		/** @var VerbosityLevel|null $verboseLevel */
+		$verboseLevel = null;
 		TypeTraverser::map($acceptingType, $moreVerboseCallback);
 
-		if ($moreVerbose) {
-			return $verboseLevelCallback($acceptingType);
+		if (null !== $verboseLevel) {
+			return $verboseLevel;
 		}
 
 		if ($acceptedType === null) {
@@ -160,11 +159,11 @@ public static function getRecommendedLevelByType(Type $acceptingType, ?Type $acc
 			return self::typeOnly();
 		}
 
-		/** @var bool $moreVerbose */
-		$moreVerbose = false;
+		/** @var VerbosityLevel|null $verboseLevel */
+		$verboseLevel = null;
 		TypeTraverser::map($acceptedType, $moreVerboseCallback);
 
-		return $moreVerbose ? $verboseLevelCallback($acceptingType) : self::typeOnly();
+		return null !== $verboseLevel ? self::value() : self::typeOnly();
 	}
 
 	/**

From 48b80eeadeeef29eb0829f1bd6d07eda7ab636db Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Mon, 16 Sep 2024 11:33:43 +0200
Subject: [PATCH 18/26] Update test

---
 tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php b/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php
index b8627bfee5..6d374a6f1c 100644
--- a/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php
+++ b/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php
@@ -834,7 +834,7 @@ public function testBug8146bErrors(): void
 		$this->checkBenevolentUnionTypes = true;
 		$this->analyse([__DIR__ . '/data/bug-8146b-errors.php'], [
 			[
-				"Method Bug8146bError\LocationFixtures::getData() should return array<non-empty-string, array<non-empty-string, array{constituencies: non-empty-list<non-empty-string>, coordinates: array{lat: float, lng: float}}>> but returns array{Bács-Kiskun: array{Ágasegyháza: array{constituencies: array{'Bács-Kiskun 4.', true, false, Bug8146bError\X, null}, coordinates: array{lat: 46.8386043, lng: 19.4502899}}, Akasztó: array{constituencies: array{'Bács-Kiskun 3.'}, coordinates: array{lat: 46.6898175, lng: 19.205086}}, Apostag: array{constituencies: array{'Bács-Kiskun 3.'}, coordinates: array{lat: 46.8812652, lng: 18.9648478}}, Bácsalmás: array{constituencies: array{'Bács-Kiskun 5.'}, coordinates: array{lat: 46.1250396, lng: 19.3357509}}, Bácsbokod: array{constituencies: array{'Bács-Kiskun 6.'}, coordinates: array{lat: 46.1234737, lng: 19.155708}}, Bácsborsód: array{constituencies: array{'Bács-Kiskun 6.'}, coordinates: array{lat: 46.0989373, lng: 19.1566725}}, Bácsszentgyörgy: array{constituencies: array{'Bács-Kiskun 6.'}, coordinates: array{lat: 45.9746039, lng: 19.0398066}}, Bácsszőlős: array{constituencies: array{'Bács-Kiskun 5.'}, coordinates: array{lat: 46.1352003, lng: 19.4215997}}, ...}, Baranya: non-empty-array<literal-string&non-falsy-string, array<literal-string&lowercase-string&non-falsy-string, array<int<0, max>|(literal-string&lowercase-string&non-falsy-string), float|(literal-string&non-falsy-string)>>>, Békés: array{Almáskamarás: array{constituencies: array{'Békés 4.'}, coordinates: array{lat: 46.4617785, lng: 21.092448}}, Battonya: array{constituencies: array{'Békés 4.'}, coordinates: array{lat: 46.2902462, lng: 21.0199215}}, Békés: array{constituencies: array{'Békés 2.'}, coordinates: array{lat: 46.6704899, lng: 21.0434996}}, Békéscsaba: array{constituencies: array{'Békés 1.'}, coordinates: array{lat: 46.6735939, lng: 21.0877309}}, Békéssámson: array{constituencies: array{'Békés 4.'}, coordinates: array{lat: 46.4208677, lng: 20.6176498}}, Békésszentandrás: array{constituencies: array{'Békés 2.'}, coordinates: array{lat: 46.8715996, lng: 20.48336}}, Bélmegyer: array{constituencies: array{'Békés 3.'}, coordinates: array{lat: 46.8726019, lng: 21.1832832}}, Biharugra: array{constituencies: array{'Békés 3.'}, coordinates: array{lat: 46.9691009, lng: 21.5987651}}, ...}, Borsod-Abaúj-Zemplén: non-empty-array<literal-string&non-falsy-string, array<literal-string&lowercase-string&non-falsy-string, array<int<0, max>|(literal-string&lowercase-string&non-falsy-string), float|(literal-string&non-falsy-string)>>>, Budapest: array{Budapest I. ker.: array{constituencies: array{'Budapest 01.'}, coordinates: array{lat: 47.4968219, lng: 19.037458}}, Budapest II. ker.: array{constituencies: array{'Budapest 03.', 'Budapest 04.'}, coordinates: array{lat: 47.5393329, lng: 18.986934}}, Budapest III. ker.: array{constituencies: array{'Budapest 04.', 'Budapest 10.'}, coordinates: array{lat: 47.5671768, lng: 19.0368517}}, Budapest IV. ker.: array{constituencies: array{'Budapest 11.', 'Budapest 12.'}, coordinates: array{lat: 47.5648915, lng: 19.0913149}}, Budapest V. ker.: array{constituencies: array{'Budapest 01.'}, coordinates: array{lat: 47.5002319, lng: 19.0520181}}, Budapest VI. ker.: array{constituencies: array{'Budapest 05.'}, coordinates: array{lat: 47.509863, lng: 19.0625813}}, Budapest VII. ker.: array{constituencies: array{'Budapest 05.'}, coordinates: array{lat: 47.5027289, lng: 19.073376}}, Budapest VIII. ker.: array{constituencies: array{'Budapest 01.', 'Budapest 06.'}, coordinates: array{lat: 47.4894184, lng: 19.070668}}, ...}, Csongrád-Csanád: array{Algyő: array{constituencies: array{'Csongrád-Csanád 4.'}, coordinates: array{lat: 46.3329625, lng: 20.207889}}, Ambrózfalva: array{constituencies: array{'Csongrád-Csanád 4.'}, coordinates: array{lat: 46.3501417, lng: 20.7313995}}, Apátfalva: array{constituencies: array{'Csongrád-Csanád 4.'}, coordinates: array{lat: 46.173317, lng: 20.5800472}}, Árpádhalom: array{constituencies: array{'Csongrád-Csanád 3.'}, coordinates: array{lat: 46.6158286, lng: 20.547733}}, Ásotthalom: array{constituencies: array{'Csongrád-Csanád 2.'}, coordinates: array{lat: 46.1995983, lng: 19.7833756}}, Baks: array{constituencies: array{'Csongrád-Csanád 3.'}, coordinates: array{lat: 46.5518708, lng: 20.1064166}}, Balástya: array{constituencies: array{'Csongrád-Csanád 3.'}, coordinates: array{lat: 46.4261828, lng: 20.004933}}, Bordány: array{constituencies: array{'Csongrád-Csanád 2.'}, coordinates: array{lat: 46.3194213, lng: 19.9227063}}, ...}, Fejér: array{Aba: array{constituencies: array{'Fejér 5.'}, coordinates: array{lat: 47.0328193, lng: 18.522359}}, Adony: array{constituencies: array{'Fejér 4.'}, coordinates: array{lat: 47.119831, lng: 18.8612469}}, Alap: array{constituencies: array{'Fejér 5.'}, coordinates: array{lat: 46.8075763, lng: 18.684028}}, Alcsútdoboz: array{constituencies: array{'Fejér 3.'}, coordinates: array{lat: 47.4277067, lng: 18.6030325}}, Alsószentiván: array{constituencies: array{'Fejér 5.'}, coordinates: array{lat: 46.7910573, lng: 18.732161}}, Bakonycsernye: array{constituencies: array{'Fejér 2.'}, coordinates: array{lat: 47.321719, lng: 18.0907379}}, Bakonykúti: array{constituencies: array{'Fejér 2.'}, coordinates: array{lat: 47.2458464, lng: 18.195769}}, Balinka: array{constituencies: array{'Fejér 2.'}, coordinates: array{lat: 47.3135736, lng: 18.1907168}}, ...}, Győr-Moson-Sopron: array{Abda: array{constituencies: array{'Győr-Moson-Sopron 5.'}, coordinates: array{lat: 47.6962149, lng: 17.5445786}}, Acsalag: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.676095, lng: 17.1977771}}, Ágfalva: array{constituencies: array{'Győr-Moson-Sopron 4.'}, coordinates: array{lat: 47.688862, lng: 16.5110233}}, Agyagosszergény: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.608545, lng: 16.9409912}}, Árpás: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.5134127, lng: 17.3931579}}, Ásványráró: array{constituencies: array{'Győr-Moson-Sopron 5.'}, coordinates: array{lat: 47.8287695, lng: 17.499195}}, Babót: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.5752269, lng: 17.0758604}}, Bágyogszovát: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.5866036, lng: 17.3617273}}, ...}, ...}.",
+				"Method Bug8146bError\LocationFixtures::getData() should return array<non-empty-string, array<non-empty-string, array{constituencies: non-empty-list<non-empty-string>, coordinates: array{lat: float, lng: float}}>> but returns array{Bács-Kiskun: array{Ágasegyháza: array{constituencies: array{'Bács-Kiskun 4.', true, false, Bug8146bError\X, null}, coordinates: array{lat: 46.8386043, lng: 19.4502899}}, Akasztó: array{constituencies: array{'Bács-Kiskun 3.'}, coordinates: array{lat: 46.6898175, lng: 19.205086}}, Apostag: array{constituencies: array{'Bács-Kiskun 3.'}, coordinates: array{lat: 46.8812652, lng: 18.9648478}}, Bácsalmás: array{constituencies: array{'Bács-Kiskun 5.'}, coordinates: array{lat: 46.1250396, lng: 19.3357509}}, Bácsbokod: array{constituencies: array{'Bács-Kiskun 6.'}, coordinates: array{lat: 46.1234737, lng: 19.155708}}, Bácsborsód: array{constituencies: array{'Bács-Kiskun 6.'}, coordinates: array{lat: 46.0989373, lng: 19.1566725}}, Bácsszentgyörgy: array{constituencies: array{'Bács-Kiskun 6.'}, coordinates: array{lat: 45.9746039, lng: 19.0398066}}, Bácsszőlős: array{constituencies: array{'Bács-Kiskun 5.'}, coordinates: array{lat: 46.1352003, lng: 19.4215997}}, ...}, Baranya: non-empty-array<literal-string&non-falsy-string, array<literal-string&non-falsy-string, array<int<0, max>|(literal-string&non-falsy-string), float|(literal-string&non-falsy-string)>>>, Békés: array{Almáskamarás: array{constituencies: array{'Békés 4.'}, coordinates: array{lat: 46.4617785, lng: 21.092448}}, Battonya: array{constituencies: array{'Békés 4.'}, coordinates: array{lat: 46.2902462, lng: 21.0199215}}, Békés: array{constituencies: array{'Békés 2.'}, coordinates: array{lat: 46.6704899, lng: 21.0434996}}, Békéscsaba: array{constituencies: array{'Békés 1.'}, coordinates: array{lat: 46.6735939, lng: 21.0877309}}, Békéssámson: array{constituencies: array{'Békés 4.'}, coordinates: array{lat: 46.4208677, lng: 20.6176498}}, Békésszentandrás: array{constituencies: array{'Békés 2.'}, coordinates: array{lat: 46.8715996, lng: 20.48336}}, Bélmegyer: array{constituencies: array{'Békés 3.'}, coordinates: array{lat: 46.8726019, lng: 21.1832832}}, Biharugra: array{constituencies: array{'Békés 3.'}, coordinates: array{lat: 46.9691009, lng: 21.5987651}}, ...}, Borsod-Abaúj-Zemplén: non-empty-array<literal-string&non-falsy-string, array<literal-string&non-falsy-string, array<int<0, max>|(literal-string&non-falsy-string), float|(literal-string&non-falsy-string)>>>, Budapest: array{Budapest I. ker.: array{constituencies: array{'Budapest 01.'}, coordinates: array{lat: 47.4968219, lng: 19.037458}}, Budapest II. ker.: array{constituencies: array{'Budapest 03.', 'Budapest 04.'}, coordinates: array{lat: 47.5393329, lng: 18.986934}}, Budapest III. ker.: array{constituencies: array{'Budapest 04.', 'Budapest 10.'}, coordinates: array{lat: 47.5671768, lng: 19.0368517}}, Budapest IV. ker.: array{constituencies: array{'Budapest 11.', 'Budapest 12.'}, coordinates: array{lat: 47.5648915, lng: 19.0913149}}, Budapest V. ker.: array{constituencies: array{'Budapest 01.'}, coordinates: array{lat: 47.5002319, lng: 19.0520181}}, Budapest VI. ker.: array{constituencies: array{'Budapest 05.'}, coordinates: array{lat: 47.509863, lng: 19.0625813}}, Budapest VII. ker.: array{constituencies: array{'Budapest 05.'}, coordinates: array{lat: 47.5027289, lng: 19.073376}}, Budapest VIII. ker.: array{constituencies: array{'Budapest 01.', 'Budapest 06.'}, coordinates: array{lat: 47.4894184, lng: 19.070668}}, ...}, Csongrád-Csanád: array{Algyő: array{constituencies: array{'Csongrád-Csanád 4.'}, coordinates: array{lat: 46.3329625, lng: 20.207889}}, Ambrózfalva: array{constituencies: array{'Csongrád-Csanád 4.'}, coordinates: array{lat: 46.3501417, lng: 20.7313995}}, Apátfalva: array{constituencies: array{'Csongrád-Csanád 4.'}, coordinates: array{lat: 46.173317, lng: 20.5800472}}, Árpádhalom: array{constituencies: array{'Csongrád-Csanád 3.'}, coordinates: array{lat: 46.6158286, lng: 20.547733}}, Ásotthalom: array{constituencies: array{'Csongrád-Csanád 2.'}, coordinates: array{lat: 46.1995983, lng: 19.7833756}}, Baks: array{constituencies: array{'Csongrád-Csanád 3.'}, coordinates: array{lat: 46.5518708, lng: 20.1064166}}, Balástya: array{constituencies: array{'Csongrád-Csanád 3.'}, coordinates: array{lat: 46.4261828, lng: 20.004933}}, Bordány: array{constituencies: array{'Csongrád-Csanád 2.'}, coordinates: array{lat: 46.3194213, lng: 19.9227063}}, ...}, Fejér: array{Aba: array{constituencies: array{'Fejér 5.'}, coordinates: array{lat: 47.0328193, lng: 18.522359}}, Adony: array{constituencies: array{'Fejér 4.'}, coordinates: array{lat: 47.119831, lng: 18.8612469}}, Alap: array{constituencies: array{'Fejér 5.'}, coordinates: array{lat: 46.8075763, lng: 18.684028}}, Alcsútdoboz: array{constituencies: array{'Fejér 3.'}, coordinates: array{lat: 47.4277067, lng: 18.6030325}}, Alsószentiván: array{constituencies: array{'Fejér 5.'}, coordinates: array{lat: 46.7910573, lng: 18.732161}}, Bakonycsernye: array{constituencies: array{'Fejér 2.'}, coordinates: array{lat: 47.321719, lng: 18.0907379}}, Bakonykúti: array{constituencies: array{'Fejér 2.'}, coordinates: array{lat: 47.2458464, lng: 18.195769}}, Balinka: array{constituencies: array{'Fejér 2.'}, coordinates: array{lat: 47.3135736, lng: 18.1907168}}, ...}, Győr-Moson-Sopron: array{Abda: array{constituencies: array{'Győr-Moson-Sopron 5.'}, coordinates: array{lat: 47.6962149, lng: 17.5445786}}, Acsalag: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.676095, lng: 17.1977771}}, Ágfalva: array{constituencies: array{'Győr-Moson-Sopron 4.'}, coordinates: array{lat: 47.688862, lng: 16.5110233}}, Agyagosszergény: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.608545, lng: 16.9409912}}, Árpás: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.5134127, lng: 17.3931579}}, Ásványráró: array{constituencies: array{'Győr-Moson-Sopron 5.'}, coordinates: array{lat: 47.8287695, lng: 17.499195}}, Babót: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.5752269, lng: 17.0758604}}, Bágyogszovát: array{constituencies: array{'Győr-Moson-Sopron 3.'}, coordinates: array{lat: 47.5866036, lng: 17.3617273}}, ...}, ...}.",
 				12,
 				"Offset 'constituencies' (non-empty-list<non-empty-string>) does not accept type array{'Bács-Kiskun 4.', true, false, Bug8146bError\X, null}.",
 			],

From 038152164056af9152d7340bb73fb7cfd10f39d6 Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Mon, 16 Sep 2024 11:46:40 +0200
Subject: [PATCH 19/26] fix test

---
 src/Type/UnionTypeHelper.php | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/Type/UnionTypeHelper.php b/src/Type/UnionTypeHelper.php
index 485c482644..f91ea5cb45 100644
--- a/src/Type/UnionTypeHelper.php
+++ b/src/Type/UnionTypeHelper.php
@@ -117,7 +117,7 @@ public static function sortTypes(array $types): array
 			}
 
 			if ($a->isString()->yes() && $b->isString()->yes()) {
-				return self::compareStrings($a->describe(VerbosityLevel::value()), $b->describe(VerbosityLevel::value()));
+				return self::compareStrings($a->describe(VerbosityLevel::precise()), $b->describe(VerbosityLevel::precise()));
 			}
 
 			return self::compareStrings($a->describe(VerbosityLevel::typeOnly()), $b->describe(VerbosityLevel::typeOnly()));

From d72fa24da5b76263ef4ab9f17f560c414de3f729 Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Mon, 16 Sep 2024 11:49:20 +0200
Subject: [PATCH 20/26] Fix cs

---
 src/Type/VerbosityLevel.php | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/Type/VerbosityLevel.php b/src/Type/VerbosityLevel.php
index 7934506aea..0e73c2631d 100644
--- a/src/Type/VerbosityLevel.php
+++ b/src/Type/VerbosityLevel.php
@@ -123,7 +123,7 @@ public static function getRecommendedLevelByType(Type $acceptingType, ?Type $acc
 		$verboseLevel = null;
 		TypeTraverser::map($acceptingType, $moreVerboseCallback);
 
-		if (null !== $verboseLevel) {
+		if ($verboseLevel !== null) {
 			return $verboseLevel;
 		}
 
@@ -163,7 +163,7 @@ public static function getRecommendedLevelByType(Type $acceptingType, ?Type $acc
 		$verboseLevel = null;
 		TypeTraverser::map($acceptedType, $moreVerboseCallback);
 
-		return null !== $verboseLevel ? self::value() : self::typeOnly();
+		return $verboseLevel !== null ? self::value() : self::typeOnly();
 	}
 
 	/**

From 1bf8d1c27fb9318201f2c4c258037c261c623e42 Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Mon, 16 Sep 2024 11:49:52 +0200
Subject: [PATCH 21/26] Fix test

---
 .../Comparison/StrictComparisonOfDifferentTypesRuleTest.php     | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php b/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php
index 33e7465bf2..e6ff6be2d7 100644
--- a/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php
+++ b/tests/PHPStan/Rules/Comparison/StrictComparisonOfDifferentTypesRuleTest.php
@@ -566,7 +566,7 @@ public function testBug6939(): void
 
 		$this->analyse([__DIR__ . '/data/bug-6939.php'], [
 			[
-				'Strict comparison using === between lowercase-string and false will always evaluate to false.',
+				'Strict comparison using === between string and false will always evaluate to false.',
 				10,
 			],
 		]);

From d141ece980553efd664f248fba4edac1e8cdc651 Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Mon, 16 Sep 2024 12:02:03 +0200
Subject: [PATCH 22/26] update rule

---
 .../Comparison/StrictComparisonOfDifferentTypesRule.php   | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/Rules/Comparison/StrictComparisonOfDifferentTypesRule.php b/src/Rules/Comparison/StrictComparisonOfDifferentTypesRule.php
index f4ea23258b..079d4f21ec 100644
--- a/src/Rules/Comparison/StrictComparisonOfDifferentTypesRule.php
+++ b/src/Rules/Comparison/StrictComparisonOfDifferentTypesRule.php
@@ -66,8 +66,8 @@ public function processNode(Node $node, Scope $scope): array
 				$addTip(RuleErrorBuilder::message(sprintf(
 					'Strict comparison using %s between %s and %s will always evaluate to false.',
 					$node->getOperatorSigil(),
-					$leftType->describe(VerbosityLevel::value()),
-					$rightType->describe(VerbosityLevel::value()),
+					$leftType->describe(VerbosityLevel::getRecommendedLevelByType($leftType, $rightType)),
+					$rightType->describe(VerbosityLevel::getRecommendedLevelByType($rightType, $leftType)),
 				)))->identifier(sprintf('%s.alwaysFalse', $node instanceof Node\Expr\BinaryOp\Identical ? 'identical' : 'notIdentical'))->build(),
 			];
 		} elseif ($this->checkAlwaysTrueStrictComparison) {
@@ -79,8 +79,8 @@ public function processNode(Node $node, Scope $scope): array
 			$errorBuilder = $addTip(RuleErrorBuilder::message(sprintf(
 				'Strict comparison using %s between %s and %s will always evaluate to true.',
 				$node->getOperatorSigil(),
-				$leftType->describe(VerbosityLevel::value()),
-				$rightType->describe(VerbosityLevel::value()),
+				$leftType->describe(VerbosityLevel::getRecommendedLevelByType($leftType, $rightType)),
+				$rightType->describe(VerbosityLevel::getRecommendedLevelByType($rightType, $leftType)),
 			)));
 			if ($isLast === false && !$this->reportAlwaysTrueInLastCondition) {
 				$errorBuilder->addTip('Remove remaining cases below this one and this error will disappear too.');

From 57ec9ee25b24f9db51889a9dd111f063fe2dd1c4 Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Mon, 16 Sep 2024 15:52:24 +0200
Subject: [PATCH 23/26] Try

---
 src/Type/VerbosityLevel.php | 35 ++++++++++++++++++++++-------------
 1 file changed, 22 insertions(+), 13 deletions(-)

diff --git a/src/Type/VerbosityLevel.php b/src/Type/VerbosityLevel.php
index 0e73c2631d..1a5151381b 100644
--- a/src/Type/VerbosityLevel.php
+++ b/src/Type/VerbosityLevel.php
@@ -87,13 +87,13 @@ public function isPrecise(): bool
 	/** @api */
 	public static function getRecommendedLevelByType(Type $acceptingType, ?Type $acceptedType = null): self
 	{
-		$moreVerboseCallback = static function (Type $type, callable $traverse) use (&$verboseLevel): Type {
+		$moreVerboseCallback = static function (Type $type, callable $traverse) use (&$moreVerbose, &$veryVerbose): Type {
 			if ($type->isCallable()->yes()) {
-				$verboseLevel = self::value();
+				$moreVerbose = true;
 				return $type;
 			}
 			if ($type->isConstantValue()->yes() && $type->isNull()->no()) {
-				$verboseLevel = self::value();
+				$moreVerbose = true;
 				return $type;
 			}
 			if (
@@ -105,26 +105,33 @@ public static function getRecommendedLevelByType(Type $acceptingType, ?Type $acc
 				|| $type instanceof NonEmptyArrayType
 				|| $type instanceof AccessoryArrayListType
 			) {
-				$verboseLevel = self::value();
+				$moreVerbose = true;
 				return $type;
 			}
 			if ($type instanceof AccessoryLowercaseStringType) {
-				$verboseLevel = self::precise();
+				$moreVerbose = true;
+				$veryVerbose = true;
 				return $type;
 			}
 			if ($type instanceof IntegerRangeType) {
-				$verboseLevel = self::value();
+				$moreVerbose = true;
 				return $type;
 			}
 			return $traverse($type);
 		};
 
-		/** @var VerbosityLevel|null $verboseLevel */
-		$verboseLevel = null;
+		/** @var bool $moreVerbose */
+		$moreVerbose = false;
+		/** @var bool $veryVerbose */
+		$veryVerbose = false;
 		TypeTraverser::map($acceptingType, $moreVerboseCallback);
 
-		if ($verboseLevel !== null) {
-			return $verboseLevel;
+		if ($veryVerbose) {
+			return self::precise();
+		}
+
+		if ($moreVerbose) {
+			return self::value();
 		}
 
 		if ($acceptedType === null) {
@@ -159,11 +166,13 @@ public static function getRecommendedLevelByType(Type $acceptingType, ?Type $acc
 			return self::typeOnly();
 		}
 
-		/** @var VerbosityLevel|null $verboseLevel */
-		$verboseLevel = null;
+		/** @var bool $moreVerbose */
+		$moreVerbose = false;
+		/** @var bool $veryVerbose */
+		$veryVerbose = false;
 		TypeTraverser::map($acceptedType, $moreVerboseCallback);
 
-		return $verboseLevel !== null ? self::value() : self::typeOnly();
+		return $moreVerbose ? self::value() : self::typeOnly();
 	}
 
 	/**

From da37d6ec4ef24d0240f7f80f8b14bee76bb8fb2e Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Thu, 26 Sep 2024 10:46:22 +0200
Subject: [PATCH 24/26] Review

---
 .../Comparison/StrictComparisonOfDifferentTypesRule.php   | 8 ++++----
 src/Type/VerbosityLevel.php                               | 4 ++++
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/Rules/Comparison/StrictComparisonOfDifferentTypesRule.php b/src/Rules/Comparison/StrictComparisonOfDifferentTypesRule.php
index 079d4f21ec..f4ea23258b 100644
--- a/src/Rules/Comparison/StrictComparisonOfDifferentTypesRule.php
+++ b/src/Rules/Comparison/StrictComparisonOfDifferentTypesRule.php
@@ -66,8 +66,8 @@ public function processNode(Node $node, Scope $scope): array
 				$addTip(RuleErrorBuilder::message(sprintf(
 					'Strict comparison using %s between %s and %s will always evaluate to false.',
 					$node->getOperatorSigil(),
-					$leftType->describe(VerbosityLevel::getRecommendedLevelByType($leftType, $rightType)),
-					$rightType->describe(VerbosityLevel::getRecommendedLevelByType($rightType, $leftType)),
+					$leftType->describe(VerbosityLevel::value()),
+					$rightType->describe(VerbosityLevel::value()),
 				)))->identifier(sprintf('%s.alwaysFalse', $node instanceof Node\Expr\BinaryOp\Identical ? 'identical' : 'notIdentical'))->build(),
 			];
 		} elseif ($this->checkAlwaysTrueStrictComparison) {
@@ -79,8 +79,8 @@ public function processNode(Node $node, Scope $scope): array
 			$errorBuilder = $addTip(RuleErrorBuilder::message(sprintf(
 				'Strict comparison using %s between %s and %s will always evaluate to true.',
 				$node->getOperatorSigil(),
-				$leftType->describe(VerbosityLevel::getRecommendedLevelByType($leftType, $rightType)),
-				$rightType->describe(VerbosityLevel::getRecommendedLevelByType($rightType, $leftType)),
+				$leftType->describe(VerbosityLevel::value()),
+				$rightType->describe(VerbosityLevel::value()),
 			)));
 			if ($isLast === false && !$this->reportAlwaysTrueInLastCondition) {
 				$errorBuilder->addTip('Remove remaining cases below this one and this error will disappear too.');
diff --git a/src/Type/VerbosityLevel.php b/src/Type/VerbosityLevel.php
index 1a5151381b..52b66c154f 100644
--- a/src/Type/VerbosityLevel.php
+++ b/src/Type/VerbosityLevel.php
@@ -172,6 +172,10 @@ public static function getRecommendedLevelByType(Type $acceptingType, ?Type $acc
 		$veryVerbose = false;
 		TypeTraverser::map($acceptedType, $moreVerboseCallback);
 
+		if ($veryVerbose) {
+			return self::precise();
+		}
+
 		return $moreVerbose ? self::value() : self::typeOnly();
 	}
 

From 6efe887854b0d8ae18406d1b3537f14dd2100ecb Mon Sep 17 00:00:00 2001
From: Vincent Langlet <vincentlanglet@hotmail.fr>
Date: Thu, 26 Sep 2024 11:01:09 +0200
Subject: [PATCH 25/26] Remove test

---
 tests/PHPStan/PhpDoc/TypeDescriptionTest.php | 2 --
 1 file changed, 2 deletions(-)

diff --git a/tests/PHPStan/PhpDoc/TypeDescriptionTest.php b/tests/PHPStan/PhpDoc/TypeDescriptionTest.php
index 7c0b2e9cc1..29c3a35231 100644
--- a/tests/PHPStan/PhpDoc/TypeDescriptionTest.php
+++ b/tests/PHPStan/PhpDoc/TypeDescriptionTest.php
@@ -4,7 +4,6 @@
 
 use PHPStan\Testing\PHPStanTestCase;
 use PHPStan\Type\Accessory\AccessoryLiteralStringType;
-use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
 use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
 use PHPStan\Type\Accessory\AccessoryNumericStringType;
 use PHPStan\Type\Accessory\NonEmptyArrayType;
@@ -30,7 +29,6 @@ public function dataTest(): iterable
 		yield ['string', new StringType()];
 		yield ['array', new ArrayType(new MixedType(), new MixedType())];
 		yield ['literal-string', new IntersectionType([new StringType(), new AccessoryLiteralStringType()])];
-		yield ['lowercase-string', new IntersectionType([new StringType(), new AccessoryLowercaseStringType()])];
 		yield ['non-empty-string', new IntersectionType([new StringType(), new AccessoryNonEmptyStringType()])];
 		yield ['numeric-string', new IntersectionType([new StringType(), new AccessoryNumericStringType()])];
 		yield ['literal-string&non-empty-string', new IntersectionType([new StringType(), new AccessoryLiteralStringType(), new AccessoryNonEmptyStringType()])];

From 7b1ade2632172a423550f357761904bdb5b8d75d Mon Sep 17 00:00:00 2001
From: Ondrej Mirtes <ondrej@mirtes.cz>
Date: Thu, 26 Sep 2024 12:59:48 +0200
Subject: [PATCH 26/26] Improve verbosity in
 StrictComparisonOfDifferentTypesRule

---
 .../StrictComparisonOfDifferentTypesRule.php  | 28 ++++++++++++++++---
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/src/Rules/Comparison/StrictComparisonOfDifferentTypesRule.php b/src/Rules/Comparison/StrictComparisonOfDifferentTypesRule.php
index f4ea23258b..c703e93cb2 100644
--- a/src/Rules/Comparison/StrictComparisonOfDifferentTypesRule.php
+++ b/src/Rules/Comparison/StrictComparisonOfDifferentTypesRule.php
@@ -7,6 +7,7 @@
 use PHPStan\Parser\LastConditionVisitor;
 use PHPStan\Rules\Rule;
 use PHPStan\Rules\RuleErrorBuilder;
+use PHPStan\TrinaryLogic;
 use PHPStan\Type\Constant\ConstantBooleanType;
 use PHPStan\Type\VerbosityLevel;
 use function sprintf;
@@ -61,13 +62,32 @@ public function processNode(Node $node, Scope $scope): array
 			return $ruleErrorBuilder->treatPhpDocTypesAsCertainTip();
 		};
 
+		$verbosity = VerbosityLevel::value();
+		if (
+			(
+				$leftType->isConstantScalarValue()->yes()
+				&& $leftType->isString()->yes()
+				&& $rightType->isConstantScalarValue()->no()
+				&& $rightType->isString()->yes()
+				&& TrinaryLogic::extremeIdentity($leftType->isLowercaseString(), $rightType->isLowercaseString())->maybe()
+			) || (
+				$rightType->isConstantScalarValue()->yes()
+				&& $rightType->isString()->yes()
+				&& $leftType->isConstantScalarValue()->no()
+				&& $leftType->isString()->yes()
+				&& TrinaryLogic::extremeIdentity($leftType->isLowercaseString(), $rightType->isLowercaseString())->maybe()
+			)
+		) {
+			$verbosity = VerbosityLevel::precise();
+		}
+
 		if (!$nodeType->getValue()) {
 			return [
 				$addTip(RuleErrorBuilder::message(sprintf(
 					'Strict comparison using %s between %s and %s will always evaluate to false.',
 					$node->getOperatorSigil(),
-					$leftType->describe(VerbosityLevel::value()),
-					$rightType->describe(VerbosityLevel::value()),
+					$leftType->describe($verbosity),
+					$rightType->describe($verbosity),
 				)))->identifier(sprintf('%s.alwaysFalse', $node instanceof Node\Expr\BinaryOp\Identical ? 'identical' : 'notIdentical'))->build(),
 			];
 		} elseif ($this->checkAlwaysTrueStrictComparison) {
@@ -79,8 +99,8 @@ public function processNode(Node $node, Scope $scope): array
 			$errorBuilder = $addTip(RuleErrorBuilder::message(sprintf(
 				'Strict comparison using %s between %s and %s will always evaluate to true.',
 				$node->getOperatorSigil(),
-				$leftType->describe(VerbosityLevel::value()),
-				$rightType->describe(VerbosityLevel::value()),
+				$leftType->describe($verbosity),
+				$rightType->describe($verbosity),
 			)));
 			if ($isLast === false && !$this->reportAlwaysTrueInLastCondition) {
 				$errorBuilder->addTip('Remove remaining cases below this one and this error will disappear too.');