Add support for tentative return types of internal methods

RFC: https://wiki.php.net/rfc/internal_method_return_types

Closses GH-6971

Author: kocsismate

UPGRADING

@@ -57,6 +57,10 @@ PHP 8.1 UPGRADE NOTES
     This means that static variables in methods now behave the same way as
     static properties.
     RFC: https://wiki.php.net/rfc/static_variable_inheritance
+  . Most non-final internal methods now require overriding methods to declare a
+    compatible return type, otherwise a deprecated notice is emitted during
+    inheritance validation.
+    RFC: https://wiki.php.net/rfc/internal_method_return_types
 
 - Fileinfo:
   . The fileinfo functions now accept and return, respectively, finfo objects

Zend/Optimizer/zend_func_info.c

@@ -844,7 +844,7 @@ ZEND_API uint32_t zend_get_func_info(
 #endif
 
 		ret = zend_get_return_info_from_signature_only(
-			callee_func, /* script */ NULL, ce, ce_is_instanceof);
+			callee_func, /* script */ NULL, ce, ce_is_instanceof, /* use_tentative_return_info */ !call_info->is_prototype);
 
 #if ZEND_DEBUG
 		if (internal_ret) {
@@ -884,7 +884,7 @@ ZEND_API uint32_t zend_get_func_info(
 		}
 		if (!ret) {
 			ret = zend_get_return_info_from_signature_only(
-				callee_func, /* TODO: script */ NULL, ce, ce_is_instanceof);
+				callee_func, /* TODO: script */ NULL, ce, ce_is_instanceof, /* use_tentative_return_info */ !call_info->is_prototype);
 		}
 	}
 	return ret;

Zend/Optimizer/zend_inference.c

@@ -4001,9 +4001,11 @@ static int is_recursive_tail_call(const zend_op_array *op_array,
 
 uint32_t zend_get_return_info_from_signature_only(
 		const zend_function *func, const zend_script *script,
-		zend_class_entry **ce, bool *ce_is_instanceof) {
+		zend_class_entry **ce, bool *ce_is_instanceof, bool use_tentative_return_info) {
 	uint32_t type;
-	if (func->common.fn_flags & ZEND_ACC_HAS_RETURN_TYPE) {
+	if (func->common.fn_flags & ZEND_ACC_HAS_RETURN_TYPE &&
+		(use_tentative_return_info || !ZEND_ARG_TYPE_IS_TENTATIVE(func->common.arg_info - 1))
+	) {
 		zend_arg_info *ret_info = func->common.arg_info - 1;
 		type = zend_fetch_arg_info_type(script, ret_info, ce);
 		*ce_is_instanceof = ce != NULL;
@@ -4025,15 +4027,15 @@ uint32_t zend_get_return_info_from_signature_only(
 ZEND_API void zend_init_func_return_info(
 	const zend_op_array *op_array, const zend_script *script, zend_ssa_var_info *ret)
 {
-	if (op_array->fn_flags & ZEND_ACC_HAS_RETURN_TYPE) {
-		zend_ssa_range tmp_range = {0, 0, 0, 0};
-		bool is_instanceof = false;
-		ret->type = zend_get_return_info_from_signature_only(
-			(zend_function *) op_array, script, &ret->ce, &is_instanceof);
-		ret->is_instanceof = is_instanceof;
-		ret->range = tmp_range;
-		ret->has_range = 0;
-	}
+	ZEND_ASSERT((op_array->fn_flags & ZEND_ACC_HAS_RETURN_TYPE));
+
+	zend_ssa_range tmp_range = {0, 0, 0, 0};
+	bool is_instanceof = false;
+	ret->type = zend_get_return_info_from_signature_only(
+		(zend_function *) op_array, script, &ret->ce, &is_instanceof, /* use_tentative_return_info */ 1);
+	ret->is_instanceof = is_instanceof;
+	ret->range = tmp_range;
+	ret->has_range = 0;
 }
 
 void zend_func_return_info(const zend_op_array   *op_array,

Zend/Optimizer/zend_inference.h

@@ -271,7 +271,7 @@ ZEND_API void zend_init_func_return_info(
 	const zend_op_array *op_array, const zend_script *script, zend_ssa_var_info *ret);
 uint32_t zend_get_return_info_from_signature_only(
 		const zend_function *func, const zend_script *script,
-		zend_class_entry **ce, bool *ce_is_instanceof);
+		zend_class_entry **ce, bool *ce_is_instanceof, bool use_tentative_return_info);
 void zend_func_return_info(const zend_op_array   *op_array,
                            const zend_script     *script,
                            int                    recursive,

Zend/tests/parameter_default_values/internal_declaration_error_class_const.phpt

@@ -4,10 +4,10 @@ The default value is a class constant in the parent class method's signature.
 <?php
 class MyDateTimeZone extends DateTimeZone
 {
-    public static function listIdentifiers()
+    public static function listIdentifiers(): array
     {
     }
 }
 ?>
 --EXPECTF--
-Fatal error: Declaration of MyDateTimeZone::listIdentifiers() must be compatible with DateTimeZone::listIdentifiers(int $timezoneGroup = DateTimeZone::ALL, ?string $countryCode = null) in %s on line %d
+Fatal error: Declaration of MyDateTimeZone::listIdentifiers(): array must be compatible with DateTimeZone::listIdentifiers(int $timezoneGroup = DateTimeZone::ALL, ?string $countryCode = null): array in %s on line %d

Zend/tests/parameter_default_values/internal_declaration_error_const.phpt

@@ -4,10 +4,10 @@ The default value is a constant in the parent class method's signature.
 <?php
 class MyDateTimeZone extends DateTimeZone
 {
-    public function getTransitions()
+    public function getTransitions(): array|false
     {
     }
 }
 ?>
 --EXPECTF--
-Fatal error: Declaration of MyDateTimeZone::getTransitions() must be compatible with DateTimeZone::getTransitions(int $timestampBegin = PHP_INT_MIN, int $timestampEnd = PHP_INT_MAX) in %s on line %d
+Fatal error: Declaration of MyDateTimeZone::getTransitions(): array|false must be compatible with DateTimeZone::getTransitions(int $timestampBegin = PHP_INT_MIN, int $timestampEnd = PHP_INT_MAX): array|false in %s on line %d

Zend/tests/parameter_default_values/internal_declaration_error_false.phpt

@@ -5,8 +5,8 @@ The default value is false in the parent class method's signature.
 
 interface MyDateTimeInterface extends DateTimeInterface
 {
-    public function diff();
+    public function diff(): DateInterval;
 }
 ?>
 --EXPECTF--
-Fatal error: Declaration of MyDateTimeInterface::diff() must be compatible with DateTimeInterface::diff(DateTimeInterface $targetObject, bool $absolute = false) in %s on line %d
+Fatal error: Declaration of MyDateTimeInterface::diff(): DateInterval must be compatible with DateTimeInterface::diff(DateTimeInterface $targetObject, bool $absolute = false): DateInterval in %s on line %d

Zend/tests/parameter_default_values/internal_declaration_error_int.phpt

@@ -4,10 +4,10 @@ The default value is an integer in the parent class method's signature.
 <?php
 class MyDateTime extends DateTime
 {
-    public function setTime(int $hour, int $minute, int $second = 0, bool $microsecond = false)
+    public function setTime(int $hour, int $minute, int $second = 0, bool $microsecond = false): DateTime
     {
     }
 }
 ?>
 --EXPECTF--
-Fatal error: Declaration of MyDateTime::setTime(int $hour, int $minute, int $second = 0, bool $microsecond = false) must be compatible with DateTime::setTime(int $hour, int $minute, int $second = 0, int $microsecond = 0) in %s on line %d
+Fatal error: Declaration of MyDateTime::setTime(int $hour, int $minute, int $second = 0, bool $microsecond = false): DateTime must be compatible with DateTime::setTime(int $hour, int $minute, int $second = 0, int $microsecond = 0): DateTime in %s on line %d

Zend/tests/parameter_default_values/internal_declaration_error_null.phpt

@@ -4,10 +4,10 @@ The default value is null in the parent class method's signature.
 <?php
 class MyDateTime extends DateTime
 {
-    public static function createFromFormat()
+    public static function createFromFormat(): DateTime|false
     {
     }
 }
 ?>
 --EXPECTF--
-Fatal error: Declaration of MyDateTime::createFromFormat() must be compatible with DateTime::createFromFormat(string $format, string $datetime, ?DateTimeZone $timezone = null) in %s on line %d
+Fatal error: Declaration of MyDateTime::createFromFormat(): DateTime|false must be compatible with DateTime::createFromFormat(string $format, string $datetime, ?DateTimeZone $timezone = null): DateTime|false in %s on line %d