Convert exception during delayed autoload to fatal error

Same as with other exceptions during inheritance, convert those
thrown during delayed class loading into fatal errors. We can't
properly deal with such exceptions, as inheritance cannot be
gracefully aborted at this point.

Fixes oss-fuzz #39405.

Author: nikic

Zend/tests/exception_during_variance_autoload.phpt

@@ -22,10 +22,7 @@ class B extends A {
 Y
 Q
 
-Warning: Uncaught Error: Class "Q" not found in %s:%d
+Fatal error: During inheritance of B, while autoloading Y: Uncaught Error: Class "Q" not found in %s:%d
 Stack trace:
 #0 %s(%d): {closure}('Y')
-#1 {main}
-  thrown in %s on line %d
-
-Fatal error: Could not check compatibility between B::method(): Y and A::method(): X, because class Y is not available in %s on line %d
+#1 {main} in %s on line %d

Zend/tests/exception_during_variance_autoload_2.phpt

@@ -0,0 +1,20 @@
+--TEST--
+Exception during delayed variance autoload (variation 2)
+--FILE--
+<?php
+spl_autoload_register(function() {
+    class Y {}
+    throw new Exception;
+});
+class A {
+    function method(): object {}
+}
+class B extends A {
+    function method(): Y {}
+}
+?>
+--EXPECTF--
+Fatal error: During inheritance of B, while autoloading Y: Uncaught Exception in %s:%d
+Stack trace:
+#0 %s(%d): {closure}('Y')
+#1 {main} in %s on line %d

Zend/zend_compile.c

@@ -1130,6 +1130,7 @@ ZEND_API zend_class_entry *zend_bind_class_in_slot(
 
 	ce = zend_do_link_class(ce, lc_parent_name, Z_STR_P(lcname));
 	if (ce) {
+		ZEND_ASSERT(!EG(exception));
 		return ce;
 	}
 

Zend/zend_inheritance.c

@@ -2485,7 +2485,7 @@ static int check_variance_obligation(zval *zv) {
 	return ZEND_HASH_APPLY_REMOVE;
 }
 
-static void load_delayed_classes(void) {
+static void load_delayed_classes(zend_class_entry *ce) {
 	HashTable *delayed_autoloads = CG(delayed_autoloads);
 	zend_string *name;
 
@@ -2499,7 +2499,9 @@ static void load_delayed_classes(void) {
 	ZEND_HASH_FOREACH_STR_KEY(delayed_autoloads, name) {
 		zend_lookup_class(name);
 		if (EG(exception)) {
-			break;
+			zend_exception_uncaught_error(
+				"During inheritance of %s, while autoloading %s",
+				ZSTR_VAL(ce->name), ZSTR_VAL(name));
 		}
 	} ZEND_HASH_FOREACH_END();
 
@@ -2908,7 +2910,7 @@ ZEND_API zend_class_entry *zend_do_link_class(zend_class_entry *ce, zend_string
 		if (CG(current_linking_class)) {
 			ce->ce_flags |= ZEND_ACC_CACHEABLE;
 		}
-		load_delayed_classes();
+		load_delayed_classes(ce);
 		if (ce->ce_flags & ZEND_ACC_UNRESOLVED_VARIANCE) {
 			resolve_delayed_variance_obligations(ce);
 			if (!(ce->ce_flags & ZEND_ACC_LINKED)) {