Error on offset assignment to specialized strings

Author: staabm

src/Type/Accessory/AccessoryLiteralStringType.php

@@ -153,6 +153,12 @@ public function getOffsetValueType(Type $offsetType): Type
 
 	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->isLiteralString()->yes()) {
 			return $this;
 		}

src/Type/Accessory/AccessoryNonEmptyStringType.php

@@ -159,6 +159,12 @@ public function getOffsetValueType(Type $offsetType): Type
 
 	public function setOffsetValueType(?Type $offsetType, Type $valueType, bool $unionValues = true): Type
 	{
+		$stringOffset = (new StringType())->setOffsetValueType($offsetType, $valueType, $unionValues);
+
+		if ($stringOffset instanceof ErrorType) {
+			return $stringOffset;
+		}
+
 		return $this;
 	}
 

src/Type/Accessory/AccessoryNonFalsyStringType.php

@@ -155,6 +155,12 @@ public function getOffsetValueType(Type $offsetType): Type
 
 	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->isNonFalsyString()->yes()) {
 			return $this;
 		}

src/Type/Accessory/AccessoryNumericStringType.php

@@ -158,6 +158,12 @@ public function getOffsetValueType(Type $offsetType): Type
 
 	public function setOffsetValueType(?Type $offsetType, Type $valueType, bool $unionValues = true): Type
 	{
+		$stringOffset = (new StringType())->setOffsetValueType($offsetType, $valueType, $unionValues);
+
+		if ($stringOffset instanceof ErrorType) {
+			return $stringOffset;
+		}
+
 		return $this;
 	}
 

tests/PHPStan/Rules/Arrays/OffsetAccessAssignmentRuleTest.php

@@ -156,4 +156,39 @@ public function testBug8015(): void
 		$this->analyse([__DIR__ . '/../../Analyser/nsrt/bug-8015.php'], []);
 	}
 
+	public function testBug11572(): void
+	{
+		$this->checkUnionTypes = true;
+		$this->analyse([__DIR__ . '/data/bug-11572.php'], [
+			[
+				'Cannot assign new offset to string.',
+				15,
+			],
+			[
+				'Cannot assign new offset to string.',
+				16,
+			],
+			[
+				'Cannot assign new offset to string.',
+				17,
+			],
+			[
+				'Cannot assign new offset to string.',
+				18,
+			],
+			[
+				'Cannot assign new offset to string.',
+				19,
+			],
+			[
+				'Cannot assign new offset to string.',
+				20,
+			],
+			[
+				'Cannot assign new offset to string.',
+				24,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Arrays/data/bug-11572.php

@@ -0,0 +1,30 @@
+<?php declare(strict_types=1);
+
+namespace bug11572;
+
+/**
+ * @param string $s
+ * @param numeric-string $numericS
+ * @param literal-string $literalS
+ * @param non-empty-string $nonEmptyS
+ * @param non-falsy-string $nonFalsyS
+ * @param non-falsy-string&literal-string $intersectedS
+ */
+function doFoo($s, $numericS, $literalS, $nonEmptyS, $nonFalsyS, $intersectedS): void
+{
+	$s[] = 'foo';
+	$numericS[] = 'foo';
+	$literalS[] = 'foo';
+	$nonEmptyS[] = 'foo';
+	$nonFalsyS[] = 'foo';
+	$intersectedS[] = 'foo';
+}
+
+$string = returnString() . ' bar';
+$string[] = 'foo';
+
+function returnString(): string
+{
+	return 'baz';
+}
+