Add RedefinedParametersRule

conf/config.level0.neon

@@ -75,6 +75,7 @@ rules:
 	- PHPStan\Rules\Functions\InnerFunctionRule
 	- PHPStan\Rules\Functions\ParamAttributesRule
 	- PHPStan\Rules\Functions\PrintfParametersRule
+	- PHPStan\Rules\Functions\RedefinedParametersRule
 	- PHPStan\Rules\Functions\ReturnNullsafeByRefRule
 	- PHPStan\Rules\Functions\VariadicParametersDeclarationRule
 	- PHPStan\Rules\Keywords\ContinueBreakInLoopRule

src/Rules/Functions/RedefinedParametersRule.php

@@ -0,0 +1,57 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Functions;
+
+use PhpParser\Node;
+use PHPStan\Analyser\Scope;
+use PHPStan\Rules\Rule;
+use PHPStan\Rules\RuleErrorBuilder;
+use function count;
+use function is_string;
+use function sprintf;
+
+/**
+ * @implements Rule<Node\FunctionLike>
+ */
+class RedefinedParametersRule implements Rule
+{
+
+	public function getNodeType(): string
+	{
+		return Node\FunctionLike::class;
+	}
+
+	public function processNode(Node $node, Scope $scope): array
+	{
+		$params = $node->getParams();
+
+		if (count($params) <= 1) {
+			return [];
+		}
+
+		$vars = [];
+		$errors = [];
+
+		foreach ($params as $param) {
+			if (!$param->var instanceof Node\Expr\Variable) {
+				continue;
+			}
+
+			if (!is_string($param->var->name)) {
+				continue;
+			}
+
+			$var = $param->var->name;
+
+			if (!isset($vars[$var])) {
+				$vars[$var] = true;
+				continue;
+			}
+
+			$errors[] = RuleErrorBuilder::message(sprintf('Redefinition of parameter $%s.', $var))->nonIgnorable()->build();
+		}
+
+		return $errors;
+	}
+
+}

tests/PHPStan/Rules/Functions/RedefinedParametersRuleTest.php

@@ -0,0 +1,37 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Functions;
+
+use PHPStan\Rules\Rule;
+use PHPStan\Testing\RuleTestCase;
+
+/**
+ * @extends RuleTestCase<RedefinedParametersRule>
+ */
+class RedefinedParametersRuleTest extends RuleTestCase
+{
+
+	protected function getRule(): Rule
+	{
+		return new RedefinedParametersRule();
+	}
+
+	public function testRule(): void
+	{
+		$this->analyse([__DIR__ . '/data/redefined-parameters.php'], [
+			[
+				'Redefinition of parameter $foo.',
+				11,
+			],
+			[
+				'Redefinition of parameter $bar.',
+				13,
+			],
+			[
+				'Redefinition of parameter $baz.',
+				15,
+			],
+		]);
+	}
+
+}

tests/PHPStan/Rules/Functions/data/redefined-parameters.php

@@ -0,0 +1,32 @@
+<?php declare(strict_types = 1);
+
+namespace RedefinedParameters;
+
+class HelloWorld
+{
+
+    /**
+     * @return \Closure(string, int): int
+     */
+	public function foo(string $foo, string $foo): \Closure
+	{
+        $callback = static fn (int $bar, array $bar): int => (int) $bar;
+
+        return function (string $baz, int $baz) use ($callback): int {
+            return $callback($baz, []);
+        };
+	}
+
+    /**
+     * @return \Closure(string, bool): int
+     */
+    public function bar(string $pipe, int $count): \Closure
+    {
+        $cb = fn (int $a, string $b): int => $a + (int) $b;
+
+        return function (string $c, bool $d) use ($cb, $pipe, $count): int {
+            return $cb((int) $d, $c) + $cb($count, $pipe);
+        };
+    }
+
+}