stream_get_contents() does not return FALSE unless an invalid position is provided

Author: staabm

src/Type/Php/StreamGetContentsFunctionReturnTypeExtension.php

@@ -0,0 +1,41 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Type\Php;
+
+use PhpParser\Node\Expr\FuncCall;
+use PHPStan\Analyser\Scope;
+use PHPStan\DependencyInjection\AutowiredService;
+use PHPStan\Reflection\FunctionReflection;
+use PHPStan\Reflection\ParametersAcceptorSelector;
+use PHPStan\Type\Constant\ConstantBooleanType;
+use PHPStan\Type\DynamicFunctionReturnTypeExtension;
+use PHPStan\Type\Type;
+use PHPStan\Type\TypeCombinator;
+use function count;
+
+#[AutowiredService]
+final class StreamGetContentsFunctionReturnTypeExtension implements DynamicFunctionReturnTypeExtension
+{
+
+	public function isFunctionSupported(FunctionReflection $functionReflection): bool
+	{
+		return $functionReflection->getName() === 'stream_get_contents';
+	}
+
+	public function getTypeFromFunctionCall(FunctionReflection $functionReflection, FuncCall $functionCall, Scope $scope): ?Type
+	{
+		if (count($functionCall->getArgs()) >= 3) {
+			return null;
+		}
+
+		// stream_get_contents() does not return FALSE unless an invalid offset is provided.
+		$returnType = ParametersAcceptorSelector::selectFromArgs(
+			$scope,
+			$functionCall->getArgs(),
+			$functionReflection->getVariants(),
+		)->getReturnType();
+
+		return TypeCombinator::remove($returnType, new ConstantBooleanType(false));
+	}
+
+}

tests/PHPStan/Rules/Methods/CallMethodsRuleTest.php

@@ -3572,4 +3572,19 @@ public function testBug13171(): void
 		]);
 	}
 
+	public function testBug3396(): void
+	{
+		$this->checkThisOnly = false;
+		$this->checkNullables = false;
+		$this->checkUnionTypes = true;
+		$this->checkExplicitMixed = false;
+
+		$this->analyse([__DIR__ . '/data/bug-3396.php'], [
+			[
+				'Parameter #1 $s of method Bug3396\HelloWorld::takesString() expects string, string|false given.',
+				18,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Methods/data/bug-3396.php

@@ -0,0 +1,20 @@
+<?php
+
+namespace Bug3396;
+
+class HelloWorld
+{
+
+	public function takesString(string $s): void
+	{
+	}
+
+	public function sayHello(): void
+	{
+		$stream = fopen("file.txt", "rb");
+		if ($stream === false) throw new \Error("wtf");
+		$this->takesString(stream_get_contents($stream));
+		$this->takesString(stream_get_contents($stream, 1));
+		$this->takesString(stream_get_contents($stream, 1, 1));
+	}
+}