Fix nullable type support

Author: iluuu1994

Zend/tests/pattern_matching/is/type.phpt

@@ -10,10 +10,16 @@ var_dump('' is string);
 var_dump('' is int);
 var_dump('' is bool);
 var_dump('' is object);
+var_dump('' is ?string);
+var_dump(null is ?string);
+var_dump('' is ?object);
 
 ?>
 --EXPECT--
 bool(true)
 bool(false)
 bool(false)
 bool(false)
+bool(true)
+bool(true)
+bool(false)

Zend/tests/pattern_matching/match/basic.phpt

@@ -11,6 +11,13 @@ class Foo {
     const FOO = 'foo';
 }
 
+var_dump(match (null) {
+    is false => wrong(),
+    is 0 => wrong(),
+    is [] => wrong(),
+    is null =>  'Literal pattern with null',
+});
+
 var_dump(match (true) {
     is false => wrong(),
     is true => 'Literal pattern with bool',
@@ -57,20 +64,14 @@ var_dump(match (15) {
     is 20 ..< 30 => wrong(),
 });
 
-// var_dump(match (true) {
-//     false if false => wrong(),
-//     false if true => wrong(),
-//     true if false => wrong(),
-//     true if true => 'Guard',
-// });
-
 // var_dump(match ('foo') {
 //     is 'bar' => wrong(),
 //     is Foo::FOO => 'Class constant literal',
 // });
 
 ?>
 --EXPECT--
+string(25) "Literal pattern with null"
 string(25) "Literal pattern with bool"
 string(24) "Literal pattern with int"
 string(27) "Literal pattern with string"

Zend/zend_compile.c

@@ -6124,7 +6124,12 @@ static void zend_compile_type_pattern(zend_ast **ast_ptr)
 {
 	zend_ast *type_pattern_ast = *ast_ptr;
 	zend_ast *type_ast = type_pattern_ast->child[0];
+	bool nullable = type_ast->attr & ZEND_TYPE_NULLABLE;
+	type_ast->attr &= ~ZEND_TYPE_NULLABLE;
 	zend_type type = zend_compile_single_typename(type_ast);
+	if (nullable) {
+		ZEND_TYPE_FULL_MASK(type) |= MAY_BE_NULL;
+	}
 	uint32_t type_mask = ZEND_TYPE_PURE_MASK(type);
 
 	// FIXME: Make sure the type mask actually fits

Zend/zend_language_parser.y

@@ -1302,7 +1302,7 @@ compound_pattern:
 
 type_pattern:
 		type_without_static			{ $$ = zend_ast_create(ZEND_AST_TYPE_PATTERN, $1); }
-	|	'?' type_without_static		{ $$ = zend_ast_create(ZEND_AST_TYPE_PATTERN, $2); $$->attr |= ZEND_TYPE_NULLABLE; }
+	|	'?' type_without_static		{ $$ = zend_ast_create(ZEND_AST_TYPE_PATTERN, $2); $2->attr |= ZEND_TYPE_NULLABLE; }
 ;
 
 scalar_pattern: