Improve impossible type checker for void-returning functions

conf/bleedingEdge.neon

@@ -21,3 +21,4 @@ parameters:
 		curlSetOptTypes: true
 		listType: true
 		missingMagicSerializationRule: true
+		nullContextForVoidReturningFunctions: true

conf/config.neon

@@ -51,6 +51,7 @@ parameters:
 		curlSetOptTypes: false
 		listType: false
 		missingMagicSerializationRule: false
+		nullContextForVoidReturningFunctions: false
 	fileExtensions:
 		- php
 	checkAdvancedIsset: false
@@ -261,6 +262,7 @@ parametersSchema:
 		curlSetOptTypes: bool()
 		listType: bool()
 		missingMagicSerializationRule: bool()
+		nullContextForVoidReturningFunctions: bool()
 	])
 	fileExtensions: listOf(string())
 	checkAdvancedIsset: bool()
@@ -909,6 +911,7 @@ services:
 		arguments:
 			universalObjectCratesClasses: %universalObjectCratesClasses%
 			treatPhpDocTypesAsCertain: %treatPhpDocTypesAsCertain%
+			nullContextForVoidReturningFunctions: %featureToggles.nullContextForVoidReturningFunctions%
 
 	-
 		class: PHPStan\Rules\Exceptions\DefaultExceptionTypeResolver
@@ -1711,6 +1714,7 @@ services:
 		arguments:
 			treatPhpDocTypesAsCertain: %treatPhpDocTypesAsCertain%
 			universalObjectCratesClasses: %universalObjectCratesClasses%
+			nullContextForVoidReturningFunctions: %featureToggles.nullContextForVoidReturningFunctions%
 		tags:
 			- phpstan.broker.dynamicFunctionReturnTypeExtension
 

src/Rules/Comparison/ImpossibleCheckTypeHelper.php

@@ -7,9 +7,11 @@
 use PhpParser\Node\Expr;
 use PhpParser\Node\Expr\FuncCall;
 use PhpParser\Node\Expr\MethodCall;
+use PhpParser\Node\Expr\StaticCall;
 use PHPStan\Analyser\Scope;
 use PHPStan\Analyser\TypeSpecifier;
 use PHPStan\Analyser\TypeSpecifierContext;
+use PHPStan\Reflection\ParametersAcceptorSelector;
 use PHPStan\Reflection\ReflectionProvider;
 use PHPStan\TrinaryLogic;
 use PHPStan\Type\Constant\ConstantArrayType;
@@ -22,6 +24,7 @@
 use PHPStan\Type\TypeUtils;
 use PHPStan\Type\TypeWithClassName;
 use PHPStan\Type\VerbosityLevel;
+use PHPStan\Type\VoidType;
 use function array_map;
 use function array_pop;
 use function count;
@@ -42,6 +45,7 @@ public function __construct(
 		private TypeSpecifier $typeSpecifier,
 		private array $universalObjectCratesClasses,
 		private bool $treatPhpDocTypesAsCertain,
+		private bool $nullContextForVoidReturningFunctions,
 	)
 	{
 	}
@@ -178,7 +182,7 @@ public function findSpecifiedType(
 			}
 		}
 
-		$specifiedTypes = $this->typeSpecifier->specifyTypesInCondition($scope, $node, TypeSpecifierContext::createTruthy());
+		$specifiedTypes = $this->typeSpecifier->specifyTypesInCondition($scope, $node, $this->determineContext($scope, $node));
 
 		// don't validate types on overwrite
 		if ($specifiedTypes->shouldOverwrite()) {
@@ -311,7 +315,50 @@ public function doNotTreatPhpDocTypesAsCertain(): self
 			$this->typeSpecifier,
 			$this->universalObjectCratesClasses,
 			false,
+			$this->nullContextForVoidReturningFunctions,
 		);
 	}
 
+	private function determineContext(Scope $scope, Expr $node): TypeSpecifierContext
+	{
+		if (!$this->nullContextForVoidReturningFunctions) {
+			return TypeSpecifierContext::createTruthy();
+		}
+
+		if ($node instanceof FuncCall && $node->name instanceof Node\Name) {
+			if ($this->reflectionProvider->hasFunction($node->name, $scope)) {
+				$functionReflection = $this->reflectionProvider->getFunction($node->name, $scope);
+				$parametersAcceptor = ParametersAcceptorSelector::selectFromArgs($scope, $node->getArgs(), $functionReflection->getVariants());
+				$returnType = TypeUtils::resolveLateResolvableTypes($parametersAcceptor->getReturnType());
+
+				return $returnType instanceof VoidType ? TypeSpecifierContext::createNull() : TypeSpecifierContext::createTruthy();
+			}
+		} elseif ($node instanceof MethodCall && $node->name instanceof Node\Identifier) {
+			$methodCalledOnType = $scope->getType($node->var);
+			$methodReflection = $scope->getMethodReflection($methodCalledOnType, $node->name->name);
+			if ($methodReflection !== null) {
+				$parametersAcceptor = ParametersAcceptorSelector::selectFromArgs($scope, $node->getArgs(), $methodReflection->getVariants());
+				$returnType = TypeUtils::resolveLateResolvableTypes($parametersAcceptor->getReturnType());
+
+				return $returnType instanceof VoidType ? TypeSpecifierContext::createNull() : TypeSpecifierContext::createTruthy();
+			}
+		} elseif ($node instanceof StaticCall && $node->name instanceof Node\Identifier) {
+			if ($node->class instanceof Node\Name) {
+				$calleeType = $scope->resolveTypeByName($node->class);
+			} else {
+				$calleeType = $scope->getType($node->class);
+			}
+
+			$staticMethodReflection = $scope->getMethodReflection($calleeType, $node->name->name);
+			if ($staticMethodReflection !== null) {
+				$parametersAcceptor = ParametersAcceptorSelector::selectFromArgs($scope, $node->getArgs(), $staticMethodReflection->getVariants());
+				$returnType = TypeUtils::resolveLateResolvableTypes($parametersAcceptor->getReturnType());
+
+				return $returnType instanceof VoidType ? TypeSpecifierContext::createNull() : TypeSpecifierContext::createTruthy();
+			}
+		}
+
+		return TypeSpecifierContext::createTruthy();
+	}
+
 }

src/Type/Php/TypeSpecifyingFunctionsDynamicReturnTypeExtension.php

@@ -26,7 +26,7 @@ class TypeSpecifyingFunctionsDynamicReturnTypeExtension implements DynamicFuncti
 	/**
 	 * @param string[] $universalObjectCratesClasses
 	 */
-	public function __construct(private ReflectionProvider $reflectionProvider, private bool $treatPhpDocTypesAsCertain, private array $universalObjectCratesClasses)
+	public function __construct(private ReflectionProvider $reflectionProvider, private bool $treatPhpDocTypesAsCertain, private array $universalObjectCratesClasses, private bool $nullContextForVoidReturningFunctions)
 	{
 	}
 
@@ -83,7 +83,7 @@ public function getTypeFromFunctionCall(
 	private function getHelper(): ImpossibleCheckTypeHelper
 	{
 		if ($this->helper === null) {
-			$this->helper = new ImpossibleCheckTypeHelper($this->reflectionProvider, $this->typeSpecifier, $this->universalObjectCratesClasses, $this->treatPhpDocTypesAsCertain);
+			$this->helper = new ImpossibleCheckTypeHelper($this->reflectionProvider, $this->typeSpecifier, $this->universalObjectCratesClasses, $this->treatPhpDocTypesAsCertain, $this->nullContextForVoidReturningFunctions);
 		}
 
 		return $this->helper;

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -1082,6 +1082,7 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/array_values.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/array_keys.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/../Rules/Methods/data/bug-8174.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/../Rules/Comparison/data/bug-8169.php');
 	}
 
 	/**

tests/PHPStan/Rules/Comparison/BooleanAndConstantConditionRuleTest.php

@@ -22,6 +22,7 @@ protected function getRule(): Rule
 					$this->getTypeSpecifier(),
 					[],
 					$this->treatPhpDocTypesAsCertain,
+					true,
 				),
 				$this->treatPhpDocTypesAsCertain,
 			),

tests/PHPStan/Rules/Comparison/BooleanNotConstantConditionRuleTest.php

@@ -23,6 +23,7 @@ protected function getRule(): Rule
 					$this->getTypeSpecifier(),
 					[],
 					$this->treatPhpDocTypesAsCertain,
+					true,
 				),
 				$this->treatPhpDocTypesAsCertain,
 			),

tests/PHPStan/Rules/Comparison/BooleanOrConstantConditionRuleTest.php

@@ -23,6 +23,7 @@ protected function getRule(): Rule
 					$this->getTypeSpecifier(),
 					[],
 					$this->treatPhpDocTypesAsCertain,
+					true,
 				),
 				$this->treatPhpDocTypesAsCertain,
 			),

tests/PHPStan/Rules/Comparison/DoWhileLoopConstantConditionRuleTest.php

@@ -22,6 +22,7 @@ protected function getRule(): Rule
 					$this->getTypeSpecifier(),
 					[],
 					$this->treatPhpDocTypesAsCertain,
+					true,
 				),
 				$this->treatPhpDocTypesAsCertain,
 			),

tests/PHPStan/Rules/Comparison/ElseIfConstantConditionRuleTest.php

@@ -22,6 +22,7 @@ protected function getRule(): Rule
 					$this->getTypeSpecifier(),
 					[],
 					$this->treatPhpDocTypesAsCertain,
+					true,
 				),
 				$this->treatPhpDocTypesAsCertain,
 			),

tests/PHPStan/Rules/Comparison/IfConstantConditionRuleTest.php

@@ -22,6 +22,7 @@ protected function getRule(): Rule
 					$this->getTypeSpecifier(),
 					[],
 					$this->treatPhpDocTypesAsCertain,
+					true,
 				),
 				$this->treatPhpDocTypesAsCertain,
 			),

tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeFunctionCallRuleTest.php

@@ -25,6 +25,7 @@ protected function getRule(): Rule
 				$this->getTypeSpecifier(),
 				[stdClass::class],
 				$this->treatPhpDocTypesAsCertain,
+				true,
 			),
 			$this->checkAlwaysTrueCheckTypeFunctionCall,
 			$this->treatPhpDocTypesAsCertain,
@@ -581,6 +582,10 @@ public function testConditionalTypesInference(): void
 				'Call to function testIsNotInt() with int will always evaluate to false.',
 				72,
 			],
+			[
+				'Call to function assertIsInt() with int will always evaluate to true.',
+				78,
+			],
 		]);
 	}
 

tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeGenericOverwriteRuleTest.php

@@ -19,6 +19,7 @@ public function getRule(): Rule
 				$this->getTypeSpecifier(),
 				[],
 				true,
+				true,
 			),
 			true,
 			true,

tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeMethodCallRuleEqualsTest.php

@@ -19,6 +19,7 @@ public function getRule(): Rule
 				$this->getTypeSpecifier(),
 				[],
 				true,
+				true,
 			),
 			true,
 			true,

tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeMethodCallRuleTest.php

@@ -21,6 +21,7 @@ public function getRule(): Rule
 				$this->getTypeSpecifier(),
 				[],
 				$this->treatPhpDocTypesAsCertain,
+				true,
 			),
 			true,
 			$this->treatPhpDocTypesAsCertain,
@@ -186,6 +187,25 @@ public function testReportPhpDoc(): void
 		]);
 	}
 
+	public function testBug8169(): void
+	{
+		$this->treatPhpDocTypesAsCertain = true;
+		$this->analyse([__DIR__ . '/data/bug-8169.php'], [
+			[
+				'Call to method Bug8169\HelloWorld::assertString() with string will always evaluate to true.',
+				19,
+			],
+			[
+				'Call to method Bug8169\HelloWorld::assertString() with string will always evaluate to true.',
+				26,
+			],
+			[
+				'Call to method Bug8169\HelloWorld::assertString() with int will always evaluate to false.',
+				33,
+			],
+		]);
+	}
+
 	public static function getAdditionalConfigFiles(): array
 	{
 		return [

tests/PHPStan/Rules/Comparison/ImpossibleCheckTypeStaticMethodCallRuleTest.php

@@ -21,6 +21,7 @@ public function getRule(): Rule
 				$this->getTypeSpecifier(),
 				[],
 				$this->treatPhpDocTypesAsCertain,
+				true,
 			),
 			true,
 			$this->treatPhpDocTypesAsCertain,

tests/PHPStan/Rules/Comparison/TernaryOperatorConstantConditionRuleTest.php

@@ -22,6 +22,7 @@ protected function getRule(): Rule
 					$this->getTypeSpecifier(),
 					[],
 					$this->treatPhpDocTypesAsCertain,
+					true,
 				),
 				$this->treatPhpDocTypesAsCertain,
 			),

tests/PHPStan/Rules/Comparison/UnreachableIfBranchesRuleTest.php

@@ -22,6 +22,7 @@ protected function getRule(): Rule
 					$this->getTypeSpecifier(),
 					[],
 					$this->treatPhpDocTypesAsCertain,
+					true,
 				),
 				$this->treatPhpDocTypesAsCertain,
 			),

tests/PHPStan/Rules/Comparison/UnreachableTernaryElseBranchRuleTest.php

@@ -22,6 +22,7 @@ protected function getRule(): Rule
 					$this->getTypeSpecifier(),
 					[],
 					$this->treatPhpDocTypesAsCertain,
+					true,
 				),
 				$this->treatPhpDocTypesAsCertain,
 			),

tests/PHPStan/Rules/Comparison/WhileLoopAlwaysFalseConditionRuleTest.php

@@ -22,6 +22,7 @@ protected function getRule(): Rule
 					$this->getTypeSpecifier(),
 					[],
 					$this->treatPhpDocTypesAsCertain,
+					true,
 				),
 				$this->treatPhpDocTypesAsCertain,
 			),

tests/PHPStan/Rules/Comparison/WhileLoopAlwaysTrueConditionRuleTest.php

@@ -22,6 +22,7 @@ protected function getRule(): Rule
 					$this->getTypeSpecifier(),
 					[],
 					$this->treatPhpDocTypesAsCertain,
+					true,
 				),
 				$this->treatPhpDocTypesAsCertain,
 			),

tests/PHPStan/Rules/Comparison/data/bug-8169.php

@@ -0,0 +1,36 @@
+<?php declare(strict_types = 1);
+
+namespace Bug8169;
+
+use function PHPStan\Testing\assertType;
+
+class HelloWorld
+{
+	/** @phpstan-assert string $var */
+	public function assertString(mixed $var): void
+	{
+	}
+
+	public function test(mixed $foo): void
+	{
+		assertType('mixed', $foo);
+		$this->assertString($foo);
+		assertType('string', $foo);
+		$this->assertString($foo); // should report as always evaluating to true?
+		assertType('string', $foo);
+	}
+
+	public function test2(string $foo): void
+	{
+		assertType('string', $foo);
+		$this->assertString($foo); // should report as always evaluating to true?
+		assertType('string', $foo);
+	}
+
+	public function test3(int $foo): void
+	{
+		assertType('int', $foo);
+		$this->assertString($foo); // should report as always evaluating to false?
+		assertType('*NEVER*', $foo);
+	}
+}