for literal return true and return false, not for return $this->foo->doFoo()

Author: staabm

src/Rules/TooWideTypehints/TooWideTypeCheck.php

@@ -2,6 +2,7 @@
 
 namespace PHPStan\Rules\TooWideTypehints;
 
+use PhpParser\Node\Expr\ConstFetch;
 use PHPStan\Analyser\Scope;
 use PHPStan\DependencyInjection\AutowiredParameter;
 use PHPStan\DependencyInjection\AutowiredService;
@@ -13,6 +14,7 @@
 use PHPStan\Rules\IdentifierRuleError;
 use PHPStan\Rules\Properties\PropertyReflectionFinder;
 use PHPStan\Rules\RuleErrorBuilder;
+use PHPStan\TrinaryLogic;
 use PHPStan\Type\Constant\ConstantBooleanType;
 use PHPStan\Type\MixedType;
 use PHPStan\Type\NullType;
@@ -25,8 +27,10 @@
 use PHPStan\Type\VerbosityLevel;
 use PHPStan\Type\VoidType;
 use function count;
+use function in_array;
 use function lcfirst;
 use function sprintf;
+use function strtolower;
 
 #[AutowiredService]
 final class TooWideTypeCheck
@@ -176,24 +180,25 @@ public function checkFunctionReturnType(
 		if (count($returnStatements) === 0) {
 			return [];
 		}
-		if (
-			count($returnStatements) === 1
-			&& (
-				$nativeFunctionReturnType->isBoolean()->yes()
-				|| $phpDocFunctionReturnType->isBoolean()->yes()
-			)
-		) {
-			return [];
-		}
 
 		$returnTypes = [];
+		$returnsLiteralTrueFalse = [];
 		foreach ($returnStatements as $returnStatement) {
 			$returnNode = $returnStatement->getReturnNode();
 			if ($returnNode->expr === null) {
 				$returnTypes[] = new VoidType();
 				continue;
 			}
 
+			if (
+				$returnNode->expr instanceof ConstFetch
+				&& in_array(strtolower($returnNode->expr->name->toString()), ['true', 'false'], true)
+			) {
+				$returnsLiteralTrueFalse[] = TrinaryLogic::createYes();
+			} else {
+				$returnsLiteralTrueFalse[] = TrinaryLogic::createNo();
+			}
+
 			$returnTypes[] = $returnStatement->getScope()->getType($returnNode->expr);
 		}
 
@@ -214,6 +219,18 @@ public function checkFunctionReturnType(
 
 		$returnType = TypeCombinator::union(...$returnTypes);
 
+		if (
+			count($returnStatements) === 1
+			&& $returnsLiteralTrueFalse !== []
+			&& TrinaryLogic::extremeIdentity(...$returnsLiteralTrueFalse)->yes()
+			&& (
+				$nativeFunctionReturnType->isBoolean()->yes()
+				|| $phpDocFunctionReturnType->isBoolean()->yes()
+			)
+		) {
+			return [];
+		}
+
 		$unionMessagePattern = sprintf('%s never returns %%s so it can be removed from the return type.', $functionDescription);
 		$boolMessagePattern = sprintf('%s never returns %%s so the return type can be changed to %%s.', $functionDescription);
 

tests/PHPStan/Rules/TooWideTypehints/TooWideFunctionReturnTypehintRuleTest.php

@@ -77,7 +77,12 @@ public function testBug13384cPhp82(): void
 	{
 		$this->reportTooWideBool = true;
 		$this->reportNestedTooWideType = true;
-		$this->analyse([__DIR__ . '/data/bug-13384c.php'], []);
+		$this->analyse([__DIR__ . '/data/bug-13384c.php'], [
+			[
+				'Function Bug13384c\callsReturnsTrue() never returns false so the return type can be changed to true.',
+				112,
+			],
+		]);
 	}
 
 	#[RequiresPhp('< 8.2')]

tests/PHPStan/Rules/TooWideTypehints/data/bug-13384c.php

@@ -104,3 +104,11 @@ function doFooPhpdoc2() {
 function doFooMixed() {
 	return true;
 }
+
+function returnsTrue(): true {
+	return true;
+}
+
+function callsReturnsTrue(): bool {
+	return returnsTrue();
+}