Implement PregGrepDynamicReturnTypeExtension

Author: staabm

conf/config.neon

@@ -1716,6 +1716,14 @@ services:
 		tags:
 			- phpstan.broker.dynamicStaticMethodReturnTypeExtension
 
+	-
+		class: PHPStan\Type\Php\PregGrepDynamicReturnTypeExtension
+		tags:
+			- phpstan.broker.dynamicFunctionReturnTypeExtension
+
+	-
+		class: PHPStan\Rules\Regexp\RegularExpressionHelper
+
 	-
 		class: PHPStan\Type\ClosureTypeFactory
 		arguments:

src/Rules/Regexp/RegularExpressionHelper.php

@@ -0,0 +1,22 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Regexp;
+
+use Nette\Utils\RegexpException;
+use Nette\Utils\Strings;
+
+final class RegularExpressionHelper
+{
+
+	public function validatePattern(string $pattern): ?string
+	{
+		try {
+			Strings::match('', $pattern);
+		} catch (RegexpException $e) {
+			return $e->getMessage();
+		}
+
+		return null;
+	}
+
+}

src/Rules/Regexp/RegularExpressionPatternRule.php

@@ -2,8 +2,6 @@
 
 namespace PHPStan\Rules\Regexp;
 
-use Nette\Utils\RegexpException;
-use Nette\Utils\Strings;
 use PhpParser\Node;
 use PhpParser\Node\Expr\FuncCall;
 use PHPStan\Analyser\Scope;
@@ -20,6 +18,12 @@
 class RegularExpressionPatternRule implements Rule
 {
 
+	public function __construct(
+		private RegularExpressionHelper $regularExpressionHelper,
+	)
+	{
+	}
+
 	public function getNodeType(): string
 	{
 		return FuncCall::class;
@@ -31,7 +35,7 @@ public function processNode(Node $node, Scope $scope): array
 
 		$errors = [];
 		foreach ($patterns as $pattern) {
-			$errorMessage = $this->validatePattern($pattern);
+			$errorMessage = $this->regularExpressionHelper->validatePattern($pattern);
 			if ($errorMessage === null) {
 				continue;
 			}
@@ -110,15 +114,4 @@ private function extractPatterns(FuncCall $functionCall, Scope $scope): array
 		return $patternStrings;
 	}
 
-	private function validatePattern(string $pattern): ?string
-	{
-		try {
-			Strings::match('', $pattern);
-		} catch (RegexpException $e) {
-			return $e->getMessage();
-		}
-
-		return null;
-	}
-
 }

src/Type/Php/PregGrepDynamicReturnTypeExtension.php

@@ -0,0 +1,58 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Type\Php;
+
+use PhpParser\Node\Expr\FuncCall;
+use PHPStan\Analyser\Scope;
+use PHPStan\Reflection\FunctionReflection;
+use PHPStan\Reflection\ParametersAcceptorSelector;
+use PHPStan\Rules\Regexp\RegularExpressionHelper;
+use PHPStan\Type\Constant\ConstantBooleanType;
+use PHPStan\Type\DynamicFunctionReturnTypeExtension;
+use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
+use function count;
+use function strtolower;
+
+class PregGrepDynamicReturnTypeExtension implements DynamicFunctionReturnTypeExtension
+{
+
+	public function __construct(
+		private RegularExpressionHelper $regularExpressionHelper,
+	)
+	{
+	}
+
+	public function isFunctionSupported(FunctionReflection $functionReflection): bool
+	{
+		return strtolower($functionReflection->getName()) === 'preg_grep';
+	}
+
+	public function getTypeFromFunctionCall(FunctionReflection $functionReflection, FuncCall $functionCall, Scope $scope): ?Type
+	{
+		$args = $functionCall->getArgs();
+		if (count($args) < 1) {
+			return null;
+		}
+
+		$patternType = $scope->getType($args[0]->value);
+		$constantStrings = $patternType->getConstantStrings();
+		if (count($constantStrings) === 0) {
+			return null;
+		}
+
+		foreach ($constantStrings as $constantString) {
+			if ($this->regularExpressionHelper->validatePattern($constantString->getValue()) !== null) {
+				return null;
+			}
+		}
+
+		$defaultReturn = ParametersAcceptorSelector::selectSingle($functionReflection->getVariants())->getReturnType();
+
+		return TypeCombinator::remove(
+			$defaultReturn,
+			new ConstantBooleanType(false),
+		);
+	}
+
+}

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -1327,6 +1327,7 @@ public function dataFileAsserts(): iterable
 
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-7915.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-9714.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/preg_grep.php');
 	}
 
 	/**

tests/PHPStan/Analyser/data/preg_grep.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace PregGrep;
+
+use function PHPStan\Testing\assertType;
+
+function compilablePattern(array $a) {
+	assertType('array', preg_grep('/^[0-9]+$/', $a));
+}
+
+function bogusPattern(array $a) {
+	assertType('array|false', preg_grep('/bogus-pattern-[0^-9]$/', $a));
+}
+
+function unknownPattern(string $p, array $a) {
+	assertType('array|false', preg_grep($p, $a));
+}
+
+function sometimesCompilablePattern(array $a) {
+	$p = '/^[0-9]+$/';
+	if (rand(0,1)) {
+		$p = '/bogus-pattern-[0^-9]$/';
+	}
+	assertType('array|false', preg_grep($p, $a));
+}

tests/PHPStan/Rules/Regexp/RegularExpressionPatternRuleTest.php

@@ -15,7 +15,7 @@ class RegularExpressionPatternRuleTest extends RuleTestCase
 
 	protected function getRule(): Rule
 	{
-		return new RegularExpressionPatternRule();
+		return new RegularExpressionPatternRule(new RegularExpressionHelper());
 	}
 
 	public function testValidRegexPatternBefore73(): void