Fix exception in assert() callback with bail enabled

Zend/tests/gh16293_001.phpt

@@ -0,0 +1,19 @@
+--TEST--
+GH-16293: Exception in assert() callback with bail enabled
+--FILE--
+<?php
+
+assert_options(ASSERT_EXCEPTION, 0);
+assert_options(ASSERT_BAIL, 1);
+assert_options(ASSERT_CALLBACK, 'f1');
+assert(false);
+
+?>
+--EXPECTF--
+Warning: assert(): assert(false) failed in %s on line %d
+
+Warning: Uncaught Error: Invalid callback f1, function "f1" not found or invalid function name in %s:%d
+Stack trace:
+#0 %s(%d): assert(false, 'assert(false)')
+#1 {main}
+  thrown in %s on line %d

Zend/tests/gh16293_002.phpt

@@ -0,0 +1,19 @@
+--TEST--
+GH-16293: Exception in assert() callback with bail enabled
+--FILE--
+<?php
+
+assert_options(ASSERT_EXCEPTION, 0);
+assert_options(ASSERT_BAIL, 1);
+assert_options(ASSERT_CALLBACK, function () {
+    throw new Exception('Boo');
+});
+assert(false);
+
+?>
+--EXPECTF--
+Warning: assert(): assert(false) failed in %s on line %d
+
+Warning: Uncaught Exception: Boo in %s:%d
+Stack trace:
+%a

ext/standard/assert.c

@@ -195,6 +195,11 @@ PHP_FUNCTION(assert)
 	}
 
 	if (ASSERTG(bail)) {
+		if (EG(exception)) {
+			/* The callback might have thrown. Use E_WARNING to print the
+			 * exception so we can avoid bailout and use unwind_exit. */
+			zend_exception_error(EG(exception), E_WARNING);
+		}
 		zend_throw_unwind_exit();
 		RETURN_THROWS();
 	} else {