Fix too wide bool in trivial methods

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;
@@ -25,8 +26,10 @@
 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
@@ -205,6 +208,18 @@ public function checkFunctionReturnType(
 
 		$returnType = TypeCombinator::union(...$returnTypes);
 
+		if (
+			count($returnStatements) === 1
+			&& $returnStatements[0]->getReturnNode()->expr instanceof ConstFetch
+			&& in_array(strtolower($returnStatements[0]->getReturnNode()->expr->name->toString()), ['true', 'false'], true)
+			&& (
+				$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/Analyser/AnalyserIntegrationTest.php

@@ -1107,23 +1107,15 @@ public function testBug8376(): void
 	public function testAssertDocblock(): void
 	{
 		$errors = $this->runAnalyse(__DIR__ . '/nsrt/assert-docblock.php');
-		$this->assertCount(8, $errors);
-		$this->assertSame('Function AssertDocblock\validateStringArrayIfTrue() never returns false so the return type can be changed to true.', $errors[0]->getMessage());
-		$this->assertSame(17, $errors[0]->getLine());
-		$this->assertSame('Function AssertDocblock\validateStringArrayIfFalse() never returns true so the return type can be changed to false.', $errors[1]->getMessage());
-		$this->assertSame(25, $errors[1]->getLine());
-		$this->assertSame('Function AssertDocblock\validateStringOrIntArray() never returns true so the return type can be changed to false.', $errors[2]->getMessage());
-		$this->assertSame(34, $errors[2]->getLine());
-		$this->assertSame('Function AssertDocblock\validateStringOrNonEmptyIntArray() never returns true so the return type can be changed to false.', $errors[3]->getMessage());
-		$this->assertSame(44, $errors[3]->getLine());
-		$this->assertSame('Call to method AssertDocblock\A::testInt() with string will always evaluate to false.', $errors[4]->getMessage());
-		$this->assertSame(218, $errors[4]->getLine());
-		$this->assertSame('Call to method AssertDocblock\A::testNotInt() with string will always evaluate to true.', $errors[5]->getMessage());
-		$this->assertSame(224, $errors[5]->getLine());
-		$this->assertSame('Call to method AssertDocblock\A::testInt() with int will always evaluate to true.', $errors[6]->getMessage());
-		$this->assertSame(232, $errors[6]->getLine());
-		$this->assertSame('Call to method AssertDocblock\A::testNotInt() with int will always evaluate to false.', $errors[7]->getMessage());
-		$this->assertSame(238, $errors[7]->getLine());
+		$this->assertCount(4, $errors);
+		$this->assertSame('Call to method AssertDocblock\A::testInt() with string will always evaluate to false.', $errors[0]->getMessage());
+		$this->assertSame(218, $errors[0]->getLine());
+		$this->assertSame('Call to method AssertDocblock\A::testNotInt() with string will always evaluate to true.', $errors[1]->getMessage());
+		$this->assertSame(224, $errors[1]->getLine());
+		$this->assertSame('Call to method AssertDocblock\A::testInt() with int will always evaluate to true.', $errors[2]->getMessage());
+		$this->assertSame(232, $errors[2]->getLine());
+		$this->assertSame('Call to method AssertDocblock\A::testNotInt() with int will always evaluate to false.', $errors[3]->getMessage());
+		$this->assertSame(238, $errors[3]->getLine());
 	}
 
 	#[RequiresPhp('>= 8.0')]

tests/PHPStan/Rules/TooWideTypehints/TooWideFunctionReturnTypehintRuleTest.php

@@ -94,6 +94,14 @@ public function testBug13384cPhp82(): void
 				'Function Bug13384c\doFooPhpdoc2() never returns true so the return type can be changed to false.',
 				100,
 			],
+			[
+				'Function Bug13384c\returnsTrueUnionReturn() never returns int so it can be removed from the return type.',
+				130,
+			],
+			[
+				'Function Bug13384c\returnsTruePhpdocUnionReturn() never returns int so it can be removed from the return type.',
+				137,
+			],
 		]);
 	}
 
@@ -111,12 +119,29 @@ public function testBug13384cPrePhp82(): void
 				'Function Bug13384c\doFooPhpdoc2() never returns true so the return type can be changed to false.',
 				100,
 			],
+			[
+				'Function Bug13384c\returnsTrueUnionReturn() never returns int so it can be removed from the return type.',
+				130,
+			],
+			[
+				'Function Bug13384c\returnsTruePhpdocUnionReturn() never returns int so it can be removed from the return type.',
+				137,
+			],
 		]);
 	}
 
 	public function testBug13384cOff(): void
 	{
-		$this->analyse([__DIR__ . '/data/bug-13384c.php'], []);
+		$this->analyse([__DIR__ . '/data/bug-13384c.php'], [
+			[
+				'Function Bug13384c\returnsTrueUnionReturn() never returns int so it can be removed from the return type.',
+				130,
+			],
+			[
+				'Function Bug13384c\returnsTruePhpdocUnionReturn() never returns int so it can be removed from the return type.',
+				137,
+			],
+		]);
 	}
 
 	public function testNestedTooWideType(): void

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

@@ -1,13 +1,13 @@
-<?php
+<?php // lint >= 8.0
 
 namespace Bug13384c;
 
 function doFoo(): bool {
-	return false;
+	return returnsFalse();
 }
 
 function doFoo2(): bool {
-	return true;
+	return returnsTrue();
 }
 
 function doFoo3(): bool {
@@ -20,22 +20,22 @@ function doFoo3(): bool {
 
 class Bug13384c {
 	public function doBarPublic(): bool {
-		return false;
+		return returnsFalse();
 	}
 
 	/**
 	 * @return false
 	 */
 	private function doBarPhpdocReturn(): bool {
-		return false;
+		return returnsFalse();
 	}
 
 	private function doBar(): bool {
-		return false;
+		return returnsFalse();
 	}
 
 	private function doBar2(): bool {
-		return true;
+		return returnsTrue();
 	}
 
 	private function doBar3(): bool {
@@ -46,25 +46,25 @@ private function doBar3(): bool {
 	}
 
 	private function doBarMixed() {
-		return true;
+		return returnsTrue();
 	}
 
 	/**
 	 * @return bool
 	 */
 	private function doBarPhpdoc() {
-		return true;
+		return returnsTrue();
 	}
 
 }
 
 class Bug13384Static {
 	private static function doBar(): bool {
-		return false;
+		return returnsFalse();
 	}
 
 	private static function doBar2(): bool {
-		return true;
+		return returnsTrue();
 	}
 
 	private static function doBar3(): bool {
@@ -75,14 +75,14 @@ private static function doBar3(): bool {
 	}
 
 	private static function doBarMixed() {
-		return true;
+		return returnsTrue();
 	}
 
 	/**
 	 * @return bool
 	 */
 	private static function doBarPhpdoc() {
-		return true;
+		return returnsTrue();
 	}
 
 }
@@ -91,16 +91,49 @@ private static function doBarPhpdoc() {
  * @return bool
  */
 function doFooPhpdoc() {
-	return true;
+	return returnsTrue();
 }
 
 /**
  * @return bool
  */
 function doFooPhpdoc2() {
-	return false;
+	return returnsFalse();
 }
 
 function doFooMixed() {
+	return returnsTrue();
+}
+
+/**
+ * @return true
+ */
+function returnsTrue(): bool {
+	return true;
+}
+
+/**
+ * @return false
+ */
+function returnsFalse(): bool {
+	return false;
+}
+
+function returnsTrueNoPhpdoc(): bool {
+	return true;
+}
+
+function returnsFalseNoPhpdoc(): bool {
+	return false;
+}
+
+function returnsTrueUnionReturn(): int|bool {
+	return true;
+}
+
+/**
+ * @return int|bool
+ */
+function returnsTruePhpdocUnionReturn() {
 	return true;
 }