Convert exception during inheritance to fatal error

Now that inheritance can throw deprecations again, these may be
converted to exception by a custom error handler. In this case
we need to convert the exception to a fatal error, as inheritance
cannot safely throw in the general case.

Author: nikic

Zend/tests/deprecation_to_exception_during_inheritance.phpt

@@ -0,0 +1,19 @@
+--TEST--
+Deprecation promoted to exception should result in fatal error during inheritance
+--FILE--
+<?php
+
+set_error_handler(function($code, $message) {
+    throw new Exception($message);
+});
+
+$class = new class extends DateTime {
+    public function getTimezone() {}
+};
+
+?>
+--EXPECTF--
+Fatal error: During inheritance of DateTime: Uncaught Exception: Declaration of DateTime@anonymous::getTimezone() should be compatible with DateTime::getTimezone(): DateTimeZone|false in %s:%d
+Stack trace:
+#0 %s(%d): {closure}(8192, 'Declaration of ...', '%s', 8)
+#1 {main} in %s on line %d

Zend/zend_exceptions.c

@@ -968,6 +968,22 @@ ZEND_API ZEND_COLD zend_result zend_exception_error(zend_object *ex, int severit
 }
 /* }}} */
 
+ZEND_NORETURN void zend_exception_uncaught_error(const char *format, ...) {
+	va_list va;
+	va_start(va, format);
+	zend_string *prefix = zend_vstrpprintf(0, format, va);
+	va_end(va);
+
+	ZEND_ASSERT(EG(exception));
+	zval exception_zv;
+	ZVAL_OBJ_COPY(&exception_zv, EG(exception));
+	zend_clear_exception();
+
+	zend_string *exception_str = zval_get_string(&exception_zv);
+	zend_error_noreturn(E_ERROR,
+		"%s: Uncaught %s", ZSTR_VAL(prefix), ZSTR_VAL(exception_str));
+}
+
 ZEND_API ZEND_COLD void zend_throw_exception_object(zval *exception) /* {{{ */
 {
 	if (exception == NULL || Z_TYPE_P(exception) != IS_OBJECT) {

Zend/zend_exceptions.h

@@ -68,6 +68,7 @@ extern ZEND_API void (*zend_throw_exception_hook)(zend_object *ex);
 
 /* show an exception using zend_error(severity,...), severity should be E_ERROR */
 ZEND_API ZEND_COLD zend_result zend_exception_error(zend_object *exception, int severity);
+ZEND_NORETURN void zend_exception_uncaught_error(const char *prefix, ...) ZEND_ATTRIBUTE_FORMAT(printf, 1, 2);
 ZEND_API zend_string *zend_trace_to_string(HashTable *trace, bool include_main);
 
 ZEND_API ZEND_COLD void zend_throw_unwind_exit(void);

Zend/zend_execute_API.c

@@ -1518,14 +1518,7 @@ zend_class_entry *zend_fetch_class_by_name(zend_string *class_name, zend_string
 		}
 		if (EG(exception)) {
 			if (!(fetch_type & ZEND_FETCH_CLASS_EXCEPTION)) {
-				zend_string *exception_str;
-				zval exception_zv;
-				ZVAL_OBJ(&exception_zv, EG(exception));
-				Z_ADDREF(exception_zv);
-				zend_clear_exception();
-				exception_str = zval_get_string(&exception_zv);
-				zend_error_noreturn(E_ERROR,
-					"During class fetch: Uncaught %s", ZSTR_VAL(exception_str));
+				zend_exception_uncaught_error("During class fetch");
 			}
 			return NULL;
 		}

Zend/zend_inheritance.c

@@ -877,6 +877,10 @@ static void ZEND_COLD emit_incompatible_method_error(
 			zend_error_at(E_DEPRECATED, NULL, func_lineno(child),
 				"Declaration of %s should be compatible with %s",
 				ZSTR_VAL(child_prototype), ZSTR_VAL(parent_prototype));
+			if (EG(exception)) {
+				zend_exception_uncaught_error(
+					"During inheritance of %s", ZSTR_VAL(parent_scope->name));
+			}
 		}
 	} else {
 		zend_error_at(E_COMPILE_ERROR, NULL, func_lineno(child),
@@ -2454,14 +2458,8 @@ static void check_unrecoverable_load_failure(zend_class_entry *ce) {
 	 || ((ce->ce_flags & ZEND_ACC_IMMUTABLE)
 	  && CG(unlinked_uses)
 	  && zend_hash_index_del(CG(unlinked_uses), (zend_long)(zend_uintptr_t)ce) == SUCCESS)) {
-		zend_string *exception_str;
-		zval exception_zv;
-		ZEND_ASSERT(EG(exception) && "Exception must have been thrown");
-		ZVAL_OBJ_COPY(&exception_zv, EG(exception));
-		zend_clear_exception();
-		exception_str = zval_get_string(&exception_zv);
-		zend_error_noreturn(E_ERROR,
-			"During inheritance of %s with variance dependencies: Uncaught %s", ZSTR_VAL(ce->name), ZSTR_VAL(exception_str));
+		zend_exception_uncaught_error(
+			"During inheritance of %s with variance dependencies", ZSTR_VAL(ce->name));
 	}
 }