Try

Author: VincentLanglet

src/Reflection/InitializerExprTypeResolver.php

@@ -1008,9 +1008,16 @@ public function getBitwiseAndTypeFromTypes(Type $leftType, Type $rightType): Typ
 			$rightType = $this->optimizeScalarType($rightType);
 		}
 
+		if ($leftType instanceof MixedType && $rightType instanceof MixedType) {
+			return new BenevolentUnionType([new IntegerType(), new StringType()]);
+		}
+
 		$leftIsString = $leftType->isString();
 		$rightIsString = $rightType->isString();
-		if ($leftIsString->yes() && $rightIsString->yes()) {
+		if (
+			($leftIsString->yes() || $leftType instanceof MixedType)
+			&& ($rightIsString->yes() || $rightType instanceof MixedType)
+		) {
 			return new StringType();
 		}
 		if ($leftIsString->maybe() && $rightIsString->maybe()) {
@@ -1087,9 +1094,16 @@ public function getBitwiseOrTypeFromTypes(Type $leftType, Type $rightType): Type
 			$rightType = $this->optimizeScalarType($rightType);
 		}
 
+		if ($leftType instanceof MixedType && $rightType instanceof MixedType) {
+			return new BenevolentUnionType([new IntegerType(), new StringType()]);
+		}
+
 		$leftIsString = $leftType->isString();
 		$rightIsString = $rightType->isString();
-		if ($leftIsString->yes() && $rightIsString->yes()) {
+		if (
+			($leftIsString->yes() || $leftType instanceof MixedType)
+			&& ($rightIsString->yes() || $rightType instanceof MixedType)
+		) {
 			return new StringType();
 		}
 		if ($leftIsString->maybe() && $rightIsString->maybe()) {
@@ -1156,9 +1170,16 @@ public function getBitwiseXorTypeFromTypes(Type $leftType, Type $rightType): Typ
 			$rightType = $this->optimizeScalarType($rightType);
 		}
 
+		if ($leftType instanceof MixedType && $rightType instanceof MixedType) {
+			return new BenevolentUnionType([new IntegerType(), new StringType()]);
+		}
+
 		$leftIsString = $leftType->isString();
 		$rightIsString = $rightType->isString();
-		if ($leftIsString->yes() && $rightIsString->yes()) {
+		if (
+			($leftIsString->yes() || $leftType instanceof MixedType)
+			&& ($rightIsString->yes() || $rightType instanceof MixedType)
+		) {
 			return new StringType();
 		}
 		if ($leftIsString->maybe() && $rightIsString->maybe()) {

tests/PHPStan/Analyser/Generator/data/gnsr.php

@@ -110,7 +110,7 @@ public function doBitwiseNot($a, int $b): void
 	public function doBitwiseAnd($a, $b, int $c, int $d): void
 	{
 		assertType('int', $a & $b);
-		assertNativeType('*ERROR*', $a & $b);
+		assertNativeType('(int|string)', $a & $b);
 		assertType('1', 1 & 1);
 		assertNativeType('1', 1 & 1);
 		assertType('int', $c & $d);
@@ -125,7 +125,7 @@ public function doBitwiseAnd($a, $b, int $c, int $d): void
 	public function doBitwiseOr($a, $b, int $c, int $d): void
 	{
 		assertType('int', $a | $b);
-		assertNativeType('*ERROR*', $a | $b);
+		assertNativeType('(int|string)', $a | $b);
 		assertType('1', 1 | 1);
 		assertNativeType('1', 1 | 1);
 		assertType('int', $c | $d);
@@ -140,7 +140,7 @@ public function doBitwiseOr($a, $b, int $c, int $d): void
 	public function doBitwiseXor($a, $b, int $c, int $d): void
 	{
 		assertType('int', $a ^ $b);
-		assertNativeType('*ERROR*', $a ^ $b);
+		assertNativeType('(int|string)', $a ^ $b);
 		assertType('0', 1 ^ 1);
 		assertNativeType('0', 1 ^ 1);
 		assertType('int', $c ^ $d);

tests/PHPStan/Analyser/nsrt/bitwise.php

@@ -19,7 +19,7 @@ function test(int $int, string $string, $stringOrInt, $mixed) : void
 	assertType('*ERROR*', $string & $mixed);
 	assertType('*ERROR*', $stringOrInt & $stringOrInt);
 	assertType('*ERROR*', $stringOrInt & $mixed);
-	assertType('*ERROR*', $mixed & $mixed);
+	assertType('(int|string)', $mixed & $mixed);
 
 	assertType('int', $int | $int);
 	assertType('*ERROR*', $int | $string);
@@ -30,7 +30,7 @@ function test(int $int, string $string, $stringOrInt, $mixed) : void
 	assertType('*ERROR*', $string | $mixed);
 	assertType('*ERROR*', $stringOrInt | $stringOrInt);
 	assertType('*ERROR*', $stringOrInt | $mixed);
-	assertType('*ERROR*', $mixed | $mixed);
+	assertType('(int|string)', $mixed | $mixed);
 
 	assertType('int', $int ^ $int);
 	assertType('*ERROR*', $int ^ $string);
@@ -41,5 +41,5 @@ function test(int $int, string $string, $stringOrInt, $mixed) : void
 	assertType('*ERROR*', $string ^ $mixed);
 	assertType('*ERROR*', $stringOrInt ^ $stringOrInt);
 	assertType('*ERROR*', $stringOrInt ^ $mixed);
-	assertType('*ERROR*', $mixed ^ $mixed);
+	assertType('(int|string)', $mixed ^ $mixed);
 }