infer non-falsy-string in string replace functions

Author: staabm

src/Type/Php/ReplaceFunctionsDynamicReturnTypeExtension.php

@@ -7,6 +7,7 @@
 use PHPStan\Reflection\FunctionReflection;
 use PHPStan\Reflection\ParametersAcceptorSelector;
 use PHPStan\Type\Accessory\AccessoryNonEmptyStringType;
+use PHPStan\Type\Accessory\AccessoryNonFalsyStringType;
 use PHPStan\Type\ArrayType;
 use PHPStan\Type\DynamicFunctionReturnTypeExtension;
 use PHPStan\Type\IntersectionType;
@@ -84,6 +85,9 @@ private function getPreliminarilyResolvedTypeFromFunctionCall(
 			if (count($functionCall->getArgs()) > $replaceArgumentPosition) {
 				$replaceArgumentType = $scope->getType($functionCall->getArgs()[$replaceArgumentPosition]->value);
 
+				if ($subjectArgumentType->isNonFalsyString()->yes() && $replaceArgumentType->isNonFalsyString()->yes()) {
+					return new IntersectionType([new StringType(), new AccessoryNonFalsyStringType()]);
+				}
 				if ($replaceArgumentType->isNonEmptyString()->yes()) {
 					return new IntersectionType([new StringType(), new AccessoryNonEmptyStringType()]);
 				}

tests/PHPStan/Analyser/LegacyNodeScopeResolverTest.php

@@ -7344,15 +7344,15 @@ public function dataReplaceFunctions(): array
 	{
 		return [
 			[
-				'non-empty-string',
+				'non-falsy-string',
 				'$expectedString',
 			],
 			[
 				'string|null',
 				'$expectedString2',
 			],
 			[
-				'non-empty-string|null',
+				'non-falsy-string|null',
 				'$anotherExpectedString',
 			],
 			[

tests/PHPStan/Analyser/data/non-empty-string-replace-functions.php

@@ -23,4 +23,12 @@ public function replace(string $search, string $replacement, string $subject){
         assertType('non-empty-string', substr_replace($subject, $replacement, 1));
         assertType('non-empty-string', substr_replace($subject, $replacement, -1));
     }
-}
+
+	function foo(float $f) {
+		$s = (string) $f;
+		assertType('numeric-string', $s);
+
+		$price = str_replace(',', '.', $s);
+		assertType('non-empty-string', $price);
+	}
+}