improve error message

Author: staabm

src/Rules/Functions/UselessFunctionReturnValueRule.php

@@ -12,6 +12,7 @@
 use PHPStan\Rules\RuleErrorBuilder;
 use function count;
 use function in_array;
+use function sprintf;
 
 /**
  * @implements Rule<Node\Expr\FuncCall>
@@ -61,7 +62,14 @@ public function processNode(Node $funcCall, Scope $scope): array
 		$reorderedArgs = $reorderedFuncCall->getArgs();
 
 		if (count($reorderedArgs) === 1 || (count($reorderedArgs) >= 2 && $scope->getType($reorderedArgs[1]->value)->isFalse()->yes())) {
-			return [RuleErrorBuilder::message('Return value of call to function ' . $functionReflection->getName() . ' is useless.')
+			return [RuleErrorBuilder::message(
+				sprintf(
+					'Return value of function %s is always true and the result is printed instead of being returned. Pass in true as parameter #%d $%s to return the output instead.',
+					$functionReflection->getName(),
+					2,
+					$parametersAcceptor->getParameters()[1]->getName(),
+				),
+			)
 				->identifier('function.uselessReturnValue')
 				->line($funcCall->getStartLine())
 				->build(),

tests/PHPStan/Rules/Functions/UselessFunctionReturnValueRuleTest.php

@@ -23,15 +23,15 @@ public function testUselessReturnValue(): void
 	{
 		$this->analyse([__DIR__ . '/data/useless-fn-return.php'], [
 			[
-				'Return value of call to function print_r is useless.',
+				'Return value of function print_r is always true and the result is printed instead of being returned. Pass in true as parameter #2 $return to return the output instead.',
 				47,
 			],
 			[
-				'Return value of call to function var_export is useless.',
+				'Return value of function var_export is always true and the result is printed instead of being returned. Pass in true as parameter #2 $return to return the output instead.',
 				56,
 			],
 			[
-				'Return value of call to function print_r is useless.',
+				'Return value of function print_r is always true and the result is printed instead of being returned. Pass in true as parameter #2 $return to return the output instead.',
 				64,
 			],
 		]);
@@ -45,7 +45,7 @@ public function testUselessReturnValuePhp8(): void
 
 		$this->analyse([__DIR__ . '/data/useless-fn-return-php8.php'], [
 			[
-				'Return value of call to function print_r is useless.',
+				'Return value of function print_r is always true and the result is printed instead of being returned. Pass in true as parameter #2 $return to return the output instead.',
 				18,
 			],
 		]);