Test for hash return types

src/Type/Php/HashFunctionsReturnTypeExtension.php

@@ -0,0 +1,50 @@
+<?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\Type\Constant\ConstantBooleanType;
+use PHPStan\Type\DynamicFunctionReturnTypeExtension;
+use PHPStan\Type\MixedType;
+use PHPStan\Type\StringType;
+use PHPStan\Type\Type;
+use PHPStan\Type\TypeUtils;
+
+final class HashFunctionsReturnTypeExtension implements DynamicFunctionReturnTypeExtension
+{
+
+	public function isFunctionSupported(FunctionReflection $functionReflection): bool
+	{
+		return $functionReflection->getName() === 'hash';
+	}
+
+	public function getTypeFromFunctionCall(FunctionReflection $functionReflection, FuncCall $functionCall, Scope $scope): Type
+	{
+		if ($functionReflection->getName() === 'hash') {
+			$defaultReturnType = new StringType();
+		} else {
+			$defaultReturnType = ParametersAcceptorSelector::selectSingle($functionReflection->getVariants())->getReturnType();
+		}
+
+		if (!isset($functionCall->args[0])) {
+			return $defaultReturnType;
+		}
+
+		$argType = $scope->getType($functionCall->args[0]->value);
+		if ($argType instanceof MixedType) {
+			return TypeUtils::toBenevolentUnion($defaultReturnType);
+		}
+
+		$values = TypeUtils::getConstantStrings($argType);
+		if (count($values) !== 1) {
+			return TypeUtils::toBenevolentUnion($defaultReturnType);
+		}
+		$string = $values[0];
+
+		return in_array($string->getValue(), hash_algos(), true) ? $defaultReturnType : new ConstantBooleanType(false);
+	}
+
+}

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -5954,6 +5954,18 @@ public function dataFunctions(): array
 				'(string|false)',
 				'$hashHmacFileVariable',
 			],
+			[
+				'string',
+				'$hash',
+			],
+			[
+				'string',
+				'$hashRaw',
+			],
+			[
+				'false',
+				'$hashRandom',
+			],
 		];
 	}
 

tests/PHPStan/Analyser/data/functions.php

@@ -135,4 +135,7 @@
 $hashHmacFileRandom = hash_hmac_file('random', 'data', 'key');
 $hashHmacFileVariable = hash_hmac_file($string, 'data', 'key');
 
+$hash = hash('sha256', 'data', false);
+$hashRaw = hash('sha256', 'data', true);
+$hashRandom = hash('random', 'data', false);
 die;