Improve lowercase string verbosity level

src/Type/VerbosityLevel.php

@@ -131,11 +131,11 @@ public static function getRecommendedLevelByType(Type $acceptingType, ?Type $acc
 		}
 
 		if ($moreVerbose) {
-			return self::value();
+			$verbosity = self::value();
 		}
 
 		if ($acceptedType === null) {
-			return self::typeOnly();
+			return $verbosity ?? self::typeOnly();
 		}
 
 		$containsInvariantTemplateType = false;
@@ -163,7 +163,7 @@ public static function getRecommendedLevelByType(Type $acceptingType, ?Type $acc
 		});
 
 		if (!$containsInvariantTemplateType) {
-			return self::typeOnly();
+			return $verbosity ?? self::typeOnly();
 		}
 
 		/** @var bool $moreVerbose */
@@ -176,7 +176,7 @@ public static function getRecommendedLevelByType(Type $acceptingType, ?Type $acc
 			return self::precise();
 		}
 
-		return $moreVerbose ? self::value() : self::typeOnly();
+		return $moreVerbose ? self::value() : $verbosity ?? self::typeOnly();
 	}
 
 	/**

tests/PHPStan/Type/VerbosityLevelTest.php

@@ -0,0 +1,61 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Type;
+
+use PHPStan\Testing\PHPStanTestCase;
+use PHPStan\Type\Accessory\AccessoryLowercaseStringType;
+use PHPStan\Type\Accessory\AccessoryNonFalsyStringType;
+use PHPStan\Type\Generic\GenericObjectType;
+use PHPStan\Type\Generic\TemplateTypeVariance;
+
+class VerbosityLevelTest extends PHPStanTestCase
+{
+
+	public function dataGetRecommendedLevelByType(): iterable
+	{
+		yield [
+			new BooleanType(),
+			new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+			VerbosityLevel::typeOnly(),
+		];
+		yield [
+			new IntersectionType([new StringType(), new AccessoryNonFalsyStringType()]),
+			new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+			VerbosityLevel::value(),
+		];
+		yield [
+			new GenericObjectType(
+				'ArrayAccess',
+				[
+					new IntegerType(),
+					new IntersectionType([new StringType(), new AccessoryNonFalsyStringType()]),
+				],
+				null,
+				null,
+				[TemplateTypeVariance::createInvariant(), TemplateTypeVariance::createInvariant()],
+			),
+			new GenericObjectType(
+				'ArrayAccess',
+				[
+					new IntegerType(),
+					new IntersectionType([new StringType(), new AccessoryLowercaseStringType()]),
+				],
+				null,
+				null,
+				[TemplateTypeVariance::createInvariant(), TemplateTypeVariance::createInvariant()],
+			),
+			VerbosityLevel::precise(),
+		];
+	}
+
+	/**
+	 * @dataProvider dataGetRecommendedLevelByType
+	 */
+	public function testGetRecommendedLevelByType(Type $acceptingType, ?Type $acceptedType, VerbosityLevel $expected): void
+	{
+		$level = VerbosityLevel::getRecommendedLevelByType($acceptingType, $acceptedType);
+
+		$this->assertSame($expected->getLevelValue(), $level->getLevelValue());
+	}
+
+}