Fix inferring template type from non-empty-string

Author: ondrejmirtes

src/Type/Constant/ConstantStringType.php

@@ -298,7 +298,11 @@ public function append(self $otherString): self
 	public function generalize(?GeneralizePrecision $precision = null): Type
 	{
 		if ($this->isClassString) {
-			return new ClassStringType();
+			if ($precision !== null && $precision->isMoreSpecific()) {
+				return new ClassStringType();
+			}
+
+			return new StringType();
 		}
 
 		if ($this->getValue() !== '' && $precision !== null && $precision->isMoreSpecific()) {

src/Type/Generic/TemplateTypeHelper.php

@@ -6,6 +6,7 @@
 use PHPStan\Type\ConstantType;
 use PHPStan\Type\ErrorType;
 use PHPStan\Type\GeneralizePrecision;
+use PHPStan\Type\StringType;
 use PHPStan\Type\Type;
 use PHPStan\Type\TypeTraverser;
 
@@ -70,6 +71,10 @@ public static function generalizeType(Type $type): Type
 				return $type->generalize(GeneralizePrecision::lessSpecific());
 			}
 
+			if ($type->isNonEmptyString()->yes()) {
+				return new StringType();
+			}
+
 			return $traverse($type);
 		});
 	}

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -447,6 +447,7 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-4970.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-5322.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/splfixedarray-iterator-types.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/../Rules/Methods/data/bug-5372.php');
 	}
 
 	/**

tests/PHPStan/Analyser/data/generics.php

@@ -147,9 +147,15 @@ function f($a, $b)
  */
 function testF($arrayOfInt, $callableOrNull)
 {
-	assertType('array<string&numeric>', f($arrayOfInt, function (int $a): string {
+	assertType('Closure(int): string&numeric', function (int $a): string {
+		return (string)$a;
+	});
+	assertType('array<string>', f($arrayOfInt, function (int $a): string {
 		return (string)$a;
 	}));
+	assertType('Closure(mixed): string', function ($a): string {
+		return (string)$a;
+	});
 	assertType('array<string>', f($arrayOfInt, function ($a): string {
 		return (string)$a;
 	}));

tests/PHPStan/Rules/Functions/CallToFunctionParametersRuleTest.php

@@ -563,11 +563,11 @@ public function testArrayReduceCallback(): void
 				5,
 			],
 			[
-				'Parameter #2 $callback of function array_reduce expects callable(non-empty-string|null, int): non-empty-string|null, Closure(string, int): non-empty-string given.',
+				'Parameter #2 $callback of function array_reduce expects callable(string|null, int): string|null, Closure(string, int): non-empty-string given.',
 				13,
 			],
 			[
-				'Parameter #2 $callback of function array_reduce expects callable(non-empty-string|null, int): non-empty-string|null, Closure(string, int): non-empty-string given.',
+				'Parameter #2 $callback of function array_reduce expects callable(string|null, int): string|null, Closure(string, int): non-empty-string given.',
 				22,
 			],
 		]);
@@ -584,11 +584,11 @@ public function testArrayReduceArrowFunctionCallback(): void
 				5,
 			],
 			[
-				'Parameter #2 $callback of function array_reduce expects callable(non-empty-string|null, int): non-empty-string|null, Closure(string, int): non-empty-string given.',
+				'Parameter #2 $callback of function array_reduce expects callable(string|null, int): string|null, Closure(string, int): non-empty-string given.',
 				11,
 			],
 			[
-				'Parameter #2 $callback of function array_reduce expects callable(non-empty-string|null, int): non-empty-string|null, Closure(string, int): non-empty-string given.',
+				'Parameter #2 $callback of function array_reduce expects callable(string|null, int): string|null, Closure(string, int): non-empty-string given.',
 				18,
 			],
 		]);

tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php

@@ -2029,4 +2029,21 @@ public function testNonEmptyStringVerbosity(): void
 		]);
 	}
 
+	public function testBug5372(): void
+	{
+		if (!self::$useStaticReflectionProvider && PHP_VERSION_ID < 70400) {
+			$this->markTestSkipped('Test requires PHP 7.4.');
+		}
+
+		$this->checkThisOnly = false;
+		$this->checkNullables = true;
+		$this->checkUnionTypes = true;
+		$this->analyse([__DIR__ . '/data/bug-5372.php'], [
+			[
+				'Parameter #1 $list of method Bug5372\Foo::takesStrings() expects Bug5372\Collection<int, string>, Bug5372\Collection<int, class-string> given.',
+				72,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Methods/data/bug-5372.php

@@ -0,0 +1,75 @@
+<?php // lint >= 7.4
+
+namespace Bug5372;
+
+use function PHPStan\Testing\assertType;
+
+/**
+ * @template TKey of array-key
+ * @template T
+ */
+class Collection
+{
+
+	/** @var array<TKey, T> */
+	private $values;
+
+	/**
+	 * @param array<TKey, T> $values
+	 */
+	public function __construct(array $values)
+	{
+		$this->values = $values;
+	}
+
+	/**
+	 * @template V
+	 *
+	 * @param callable(T): V $callback
+	 *
+	 * @return self<TKey, V>
+	 */
+	public function map(callable $callback): self {
+		return new self(array_map($callback, $this->values));
+	}
+
+	/**
+	 * @template V of string
+	 *
+	 * @param callable(T): V $callback
+	 *
+	 * @return self<TKey, V>
+	 */
+	public function map2(callable $callback): self {
+		return new self(array_map($callback, $this->values));
+	}
+}
+
+class Foo
+{
+
+	/** @param Collection<int, string> $list */
+	function takesStrings(Collection $list): void {
+		echo serialize($list);
+	}
+
+	/** @param class-string $classString */
+	public function doFoo(string $classString)
+	{
+		$col = new Collection(['foo', 'bar']);
+		assertType('Bug5372\Collection<int, string>', $col);
+
+		$newCol = $col->map(static fn(string $var): string => $var . 'bar');
+		assertType('Bug5372\Collection<int, string>', $newCol);
+		$this->takesStrings($newCol);
+
+		$newCol = $col->map(static fn(string $var): string => $classString);
+		assertType('Bug5372\Collection<int, string>', $newCol);
+		$this->takesStrings($newCol);
+
+		$newCol = $col->map2(static fn(string $var): string => $classString);
+		assertType('Bug5372\Collection<int, class-string>', $newCol);
+		$this->takesStrings($newCol);
+	}
+
+}