Report NoDiscard above never return type + implicit void methods reported too

Author: ondrejmirtes

src/Rules/FunctionDefinitionCheck.php

@@ -31,6 +31,7 @@
 use PHPStan\ShouldNotHappenException;
 use PHPStan\Type\ConditionalTypeForParameter;
 use PHPStan\Type\Generic\TemplateType;
+use PHPStan\Type\NeverType;
 use PHPStan\Type\NonexistentParentClassType;
 use PHPStan\Type\ParserNodeTypeToPHPStanType;
 use PHPStan\Type\Type;
@@ -109,7 +110,7 @@ public function checkAnonymousFunction(
 		string $unionTypesMessage,
 		string $unresolvableParameterTypeMessage,
 		string $unresolvableReturnTypeMessage,
-		string $noDiscardVoidReturnMessage,
+		string $noDiscardReturnTypeMessage,
 	): array
 	{
 		$errors = [];
@@ -202,11 +203,14 @@ public function checkAnonymousFunction(
 		if ($returnTypeNode === null) {
 			return $errors;
 		}
-		if ($returnTypeNode instanceof Identifier && $returnTypeNode->name === 'void') {
+		if (
+			$returnTypeNode instanceof Identifier
+			&& in_array($returnTypeNode->toLowerString(), ['void', 'never'], true)
+		) {
 			foreach ($attribGroups as $attribGroup) {
 				foreach ($attribGroup->attrs as $attrib) {
 					if (strtolower($attrib->name->name) === 'nodiscard') {
-						$errors[] = RuleErrorBuilder::message($noDiscardVoidReturnMessage)
+						$errors[] = RuleErrorBuilder::message(sprintf($noDiscardReturnTypeMessage, $returnTypeNode->toString()))
 							->line($returnTypeNode->getStartLine())
 							->identifier('attribute.target')
 							->build();
@@ -349,7 +353,7 @@ private function checkParametersAcceptor(
 		string $templateTypeMissingInParameterMessage,
 		string $unresolvableParameterTypeMessage,
 		string $unresolvableReturnTypeMessage,
-		string $noDiscardVoidReturnMessage,
+		string $noDiscardReturnTypeMessage,
 	): array
 	{
 		$errors = [];
@@ -495,11 +499,12 @@ private function checkParametersAcceptor(
 			}
 		}
 		if ($parametersAcceptor->mustUseReturnValue()->yes()) {
-			$returnType = $functionNode->getReturnType();
-			if ($returnType instanceof Identifier
-				&& $returnType->name === 'void'
+			$returnType = $parametersAcceptor->getReturnType();
+			if (
+				$returnType->isVoid()->yes()
+				|| ($returnType instanceof NeverType && $returnType->isExplicit())
 			) {
-				$errors[] = RuleErrorBuilder::message($noDiscardVoidReturnMessage)
+				$errors[] = RuleErrorBuilder::message(sprintf($noDiscardReturnTypeMessage, $returnType->describe(VerbosityLevel::typeOnly())))
 					->line($returnTypeNode->getStartLine())
 					->identifier('attribute.target')
 					->build();

src/Rules/Functions/ExistingClassesInArrowFunctionTypehintsRule.php

@@ -52,7 +52,7 @@ public function processNode(Node $node, Scope $scope): array
 			'Anonymous function uses native union types but they\'re supported only on PHP 8.0 and later.',
 			'Parameter $%s of anonymous function has unresolvable native type.',
 			'Anonymous function has unresolvable native return type.',
-			'Attribute NoDiscard cannot be used on void anonymous function.',
+			'Attribute NoDiscard cannot be used on %s anonymous function.',
 		));
 	}
 

src/Rules/Functions/ExistingClassesInClosureTypehintsRule.php

@@ -37,7 +37,7 @@ public function processNode(Node $node, Scope $scope): array
 			'Anonymous function uses native union types but they\'re supported only on PHP 8.0 and later.',
 			'Parameter $%s of anonymous function has unresolvable native type.',
 			'Anonymous function has unresolvable native return type.',
-			'Attribute NoDiscard cannot be used on void anonymous function.',
+			'Attribute NoDiscard cannot be used on %s anonymous function.',
 		);
 	}
 

src/Rules/Functions/ExistingClassesInTypehintsRule.php

@@ -54,7 +54,7 @@ public function processNode(Node $node, Scope $scope): array
 				$functionName,
 			),
 			sprintf(
-				'Attribute NoDiscard cannot be used on void function %s().',
+				'Attribute NoDiscard cannot be used on %%s function %s().',
 				$functionName,
 			),
 		);

src/Rules/Methods/ExistingClassesInTypehintsRule.php

@@ -65,7 +65,7 @@ public function processNode(Node $node, Scope $scope): array
 				$methodName,
 			),
 			sprintf(
-				'Attribute NoDiscard cannot be used on void method %s::%s().',
+				'Attribute NoDiscard cannot be used on %%s method %s::%s().',
 				$className,
 				$methodName,
 			),

tests/PHPStan/Rules/Functions/ExistingClassesInArrowFunctionTypehintsRuleTest.php

@@ -331,6 +331,10 @@ public function testNoDiscardVoid(): void
 				'Attribute NoDiscard cannot be used on void anonymous function.',
 				10,
 			],
+			[
+				'Attribute NoDiscard cannot be used on never anonymous function.',
+				15,
+			],
 		]);
 	}
 

tests/PHPStan/Rules/Functions/ExistingClassesInClosureTypehintsRuleTest.php

@@ -360,6 +360,10 @@ public function testNoDiscardVoid(): void
 				'Attribute NoDiscard cannot be used on void anonymous function.',
 				5,
 			],
+			[
+				'Attribute NoDiscard cannot be used on never anonymous function.',
+				10,
+			],
 		]);
 	}
 

tests/PHPStan/Rules/Functions/ExistingClassesInTypehintsRuleTest.php

@@ -496,6 +496,10 @@ public function testNoDiscardVoid(): void
 				'Attribute NoDiscard cannot be used on void function TestFunctionTypehints\nothing().',
 				6,
 			],
+			[
+				'Attribute NoDiscard cannot be used on never function TestFunctionTypehints\returnNever().',
+				10,
+			],
 		]);
 	}
 

tests/PHPStan/Rules/Functions/data/arrow-function-typehints-nodiscard.php

@@ -10,4 +10,9 @@ public function doFoo()
 		#[\NoDiscard] fn(): void => true;
 	}
 
+	public function doBar()
+	{
+		#[\NoDiscard] fn(): never => true;
+	}
+
 }

tests/PHPStan/Rules/Functions/data/closure-typehints-nodiscard.php

@@ -6,3 +6,8 @@
 {
 
 };
+
+$callbackNever = #[\NoDiscard] function (): never
+{
+
+};