Make false|null be represented as ?false

Author: Girgias

Zend/zend_compile.c

@@ -1255,7 +1255,7 @@ zend_string *zend_type_to_string_resolved(zend_type type, zend_class_entry *scop
 
 	if (type_mask & MAY_BE_NULL) {
 		bool is_union = !str || memchr(ZSTR_VAL(str), '|', ZSTR_LEN(str)) != NULL;
-		if (!is_union && !zend_string_equals_literal(str, "false")) {
+		if (!is_union) {
 			zend_string *nullable_str = zend_string_concat2("?", 1, ZSTR_VAL(str), ZSTR_LEN(str));
 			zend_string_release(str);
 			return nullable_str;

ext/reflection/php_reflection.c

@@ -1342,10 +1342,6 @@ static reflection_type_kind get_type_kind(zend_type type) {
 	if (type_mask_without_null == MAY_BE_BOOL || ZEND_TYPE_PURE_MASK(type) == MAY_BE_ANY) {
 		return NAMED_TYPE;
 	}
-	/* null|false must be a union type */
-	if (ZEND_TYPE_PURE_MASK(type) == (MAY_BE_NULL|MAY_BE_FALSE)) {
-		return UNION_TYPE;
-	}
 	/* Check that only one bit is set. */
 	if ((type_mask_without_null & (type_mask_without_null - 1)) != 0) {
 		return UNION_TYPE;

ext/reflection/tests/union_types.phpt

@@ -13,6 +13,13 @@ function dumpType(ReflectionUnionType $rt) {
     }
 }
 
+function dumpBCType(ReflectionNamedType $rt) {
+    echo "Type $rt:\n";
+    echo "  Name: " . $rt->getName() . "\n";
+    echo "  String: " . (string) $rt . "\n";
+    echo "  Allows Null: " . ($rt->allowsNull() ? "true" : "false") . "\n";
+}
+
 function test1(): X|Y|int|float|false|null { }
 function test2(): X|iterable|bool { }
 function test3(): null|false { }
@@ -24,8 +31,8 @@ class Test {
 
 dumpType((new ReflectionFunction('test1'))->getReturnType());
 dumpType((new ReflectionFunction('test2'))->getReturnType());
-dumpType((new ReflectionFunction('test3'))->getReturnType());
-dumpType((new ReflectionFunction('test4'))->getReturnType());
+dumpBCType((new ReflectionFunction('test3'))->getReturnType());
+dumpBCType((new ReflectionFunction('test4'))->getReturnType());
 
 $rc = new ReflectionClass(Test::class);
 $rp = $rc->getProperty('prop');
@@ -79,21 +86,13 @@ Allows null: false
   Name: bool
   String: bool
   Allows Null: false
-Type false|null:
-Allows null: true
+Type ?false:
   Name: false
-  String: false
-  Allows Null: false
-  Name: null
-  String: null
+  String: ?false
   Allows Null: true
-Type false|null:
-Allows null: true
+Type ?false:
   Name: false
-  String: false
-  Allows Null: false
-  Name: null
-  String: null
+  String: ?false
   Allows Null: true
 Type X|Y|int:
 Allows null: false