PostInc of literal-string leads to literal-string

Author: ondrejmirtes

src/Analyser/MutatingScope.php

@@ -1846,6 +1846,9 @@ private function resolveType(Expr $node): Type
 
 			$stringType = new StringType();
 			if ($stringType->isSuperTypeOf($varType)->yes()) {
+				if ($varType->isLiteralString()->yes()) {
+					return new IntersectionType([$stringType, new AccessoryLiteralStringType()]);
+				}
 				return $stringType;
 			}
 

tests/PHPStan/Analyser/data/literal-string.php

@@ -39,4 +39,14 @@ public function doFoo($literalString, string $string)
 		assertType('string', implode($literalString, [$string]));
 	}
 
+	/** @param literal-string $literalString */
+	public function increment($literalString, string $string)
+	{
+		$literalString++;
+		assertType('literal-string', $literalString);
+
+		$string++;
+		assertType('string', $string);
+	}
+
 }