Added ImplodeFunctionRule

conf/config.level5.neon

@@ -11,6 +11,8 @@ parameters:
 	checkFunctionArgumentTypes: true
 	checkArgumentsPassedByReference: true
 
+rules:
+	- PHPStan\Rules\Functions\ImplodeFunctionRule
 
 services:
 	-

src/Rules/Functions/ImplodeFunctionRule.php

@@ -0,0 +1,82 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Functions;
+
+use PhpParser\Node;
+use PhpParser\Node\Expr\FuncCall;
+use PHPStan\Analyser\Scope;
+use PHPStan\Reflection\ReflectionProvider;
+use PHPStan\Rules\RuleErrorBuilder;
+use PHPStan\Rules\RuleLevelHelper;
+use PHPStan\Type\ErrorType;
+use PHPStan\Type\Type;
+use PHPStan\Type\VerbosityLevel;
+
+/**
+ * @implements \PHPStan\Rules\Rule<\PhpParser\Node\Expr\FuncCall>
+ */
+class ImplodeFunctionRule implements \PHPStan\Rules\Rule
+{
+
+	private RuleLevelHelper $ruleLevelHelper;
+
+	private ReflectionProvider $reflectionProvider;
+
+	public function __construct(
+		ReflectionProvider $reflectionProvider,
+		RuleLevelHelper $ruleLevelHelper
+	)
+	{
+		$this->reflectionProvider = $reflectionProvider;
+		$this->ruleLevelHelper = $ruleLevelHelper;
+	}
+
+	public function getNodeType(): string
+	{
+		return FuncCall::class;
+	}
+
+	public function processNode(Node $node, Scope $scope): array
+	{
+		if (!($node->name instanceof \PhpParser\Node\Name)) {
+			return [];
+		}
+
+		$functionName = $this->reflectionProvider->resolveFunctionName($node->name, $scope);
+		if (!in_array($functionName, ['implode', 'join'], true)) {
+			return [];
+		}
+
+		$args = $node->getArgs();
+		if (count($args) === 1) {
+			$arrayArg = $args[0]->value;
+			$paramNo = 1;
+		} elseif (count($args) === 2) {
+			$arrayArg = $args[1]->value;
+			$paramNo = 2;
+		} else {
+			return [];
+		}
+
+		$typeResult = $this->ruleLevelHelper->findTypeToCheck(
+			$scope,
+			$arrayArg,
+			'',
+			static function (Type $type): bool {
+				return !$type->getIterableValueType()->toString() instanceof ErrorType;
+			}
+		);
+
+		if ($typeResult->getType() instanceof ErrorType
+			|| !$typeResult->getType()->getIterableValueType()->toString() instanceof ErrorType) {
+			return [];
+		}
+
+		return [
+			RuleErrorBuilder::message(
+				sprintf('Parameter #%d $array of function %s expects array<string>, %s given.', $paramNo, $functionName, $typeResult->getType()->getIterableValueType()->describe(VerbosityLevel::typeOnly()))
+			)->build(),
+		];
+	}
+
+}

tests/PHPStan/Levels/data/acceptTypes-5.json

@@ -198,5 +198,10 @@
         "message": "Parameter #1 $nonEmpty of method Levels\\AcceptTypes\\AcceptNonEmpty::doBar() expects array&nonEmpty, array given.",
         "line": 735,
         "ignorable": true
+    },
+    {
+        "message": "Parameter #2 $pieces of function implode expects array, int given.",
+        "line": 763,
+        "ignorable": true
     }
 ]

tests/PHPStan/Levels/data/acceptTypes-6.json

@@ -148,5 +148,20 @@
         "message": "Method Levels\\AcceptTypes\\ArrayShapes::doBar() has no return type specified.",
         "line": 603,
         "ignorable": true
+    },
+    {
+        "message": "Method Levels\\AcceptTypes\\Implode::partlySupportedUnion() has no return type specified.",
+        "line": 755,
+        "ignorable": true
+    },
+    {
+        "message": "Method Levels\\AcceptTypes\\Implode::partlySupportedUnion() has parameter $union with no value type specified in iterable type array.",
+        "line": 755,
+        "ignorable": true
+    },
+    {
+        "message": "Method Levels\\AcceptTypes\\Implode::invalidType() has no return type specified.",
+        "line": 762,
+        "ignorable": true
     }
 ]

tests/PHPStan/Levels/data/acceptTypes-7.json

@@ -153,5 +153,10 @@
         "message": "Parameter #1 $min (int<-1, 1>) of function random_int expects lower number than parameter #2 $max (int<-1, 1>).",
         "line": 692,
         "ignorable": true
+    },
+    {
+        "message": "Parameter #2 $pieces of function implode expects array, array|int|string given.",
+        "line": 756,
+        "ignorable": true
     }
 ]

tests/PHPStan/Levels/data/acceptTypes.php

@@ -747,3 +747,19 @@ public function doBar(
 	}
 
 }
+
+class Implode {
+	/**
+	 * @param string|int|array $union
+	 */
+	public function partlySupportedUnion($union) {
+		$imploded = implode('abc', $union);
+	}
+
+	/**
+	 * @param int $invalid
+	 */
+	public function invalidType($invalid) {
+		$imploded = implode('abc', $invalid);
+	}
+}

tests/PHPStan/Rules/Functions/ImplodeFunctionRuleTest.php

@@ -0,0 +1,49 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Functions;
+
+use PHPStan\Rules\RuleLevelHelper;
+
+/**
+ * @extends \PHPStan\Testing\RuleTestCase<ImplodeFunctionRule>
+ */
+class ImplodeFunctionRuleTest extends \PHPStan\Testing\RuleTestCase
+{
+
+	protected function getRule(): \PHPStan\Rules\Rule
+	{
+		$broker = $this->createReflectionProvider();
+		return new ImplodeFunctionRule($broker, new RuleLevelHelper($broker, true, false, true, false));
+	}
+
+	public function testFile(): void
+	{
+		$this->analyse([__DIR__ . '/data/implode.php'], [
+			[
+				'Parameter #2 $array of function implode expects array<string>, array<int, string>|string given.',
+				9,
+			],
+			[
+				'Parameter #1 $array of function implode expects array<string>, array<int, string> given.',
+				11,
+			],
+			[
+				'Parameter #1 $array of function implode expects array<string>, array<int, int> given.',
+				12,
+			],
+			[
+				'Parameter #1 $array of function implode expects array<string>, array<int, int|true> given.',
+				13,
+			],
+			[
+				'Parameter #2 $array of function implode expects array<string>, array<int, string> given.',
+				15,
+			],
+			[
+				'Parameter #2 $array of function join expects array<string>, array<int, string> given.',
+				16,
+			],
+		]);
+	}
+
+}

tests/PHPStan/Rules/Functions/data/implode.php

@@ -0,0 +1,25 @@
+<?php declare(strict_types = 1);
+
+namespace ImplodeFunction;
+
+class Foo
+{
+	public function invalidArgs(): void
+	{
+		implode('', ['12', '123', ['1234', '12345']]);
+
+		implode([['1234', '12345']]);
+		implode([[1234, 12345]]);
+		implode([[true, 12345]]);
+
+		implode('', [['1234', '12345']]);
+		join('', [['1234', '12345']]);
+	}
+
+	public function valid() {
+		implode(['12', '345']);
+
+		implode('', ['12', '345']);
+		join('', ['12', '345']);
+	}
+}