From 737e8ea18328c0606213e48838b25623059f7431 Mon Sep 17 00:00:00 2001
From: Sebastian Pipping <sebastian@pipping.org>
Date: Fri, 26 Jan 2024 15:31:52 +0100
Subject: [PATCH] tests/misc_tests.c: Address clang-tidy 18 warning
 EnumCastOutOfRange

clang-tidy output was:
> [..]/libexpat/expat/tests/misc_tests.c:112:23: note: The value '-1' provided to the cast expression is not in the valid range of values for 'XML_Error'
>   112 |   if (XML_ErrorString((enum XML_Error) - 1) != NULL)
>       |                       ^~~~~~~~~~~~~~~~~~~~
> [..]/libexpat/expat/tests/misc_tests.c:114:23: error: The value '100' provided to the cast expression is not in the valid range of values for 'XML_Error' [clang-analyzer-optin.core.EnumCastOutOfRange,-warnings-as-errors]
>   114 |   if (XML_ErrorString((enum XML_Error)100) != NULL)
>       |                       ^~~~~~~~~~~~~~~~~~~
---
 expat/tests/misc_tests.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/expat/tests/misc_tests.c b/expat/tests/misc_tests.c
index 029572d1..377bc7ae 100644
--- a/expat/tests/misc_tests.c
+++ b/expat/tests/misc_tests.c
@@ -107,12 +107,34 @@ START_TEST(test_misc_null_parser) {
 }
 END_TEST
 
+#if defined(__has_feature)
+#  if __has_feature(undefined_behavior_sanitizer)
+#    define EXPAT_TESTS_UBSAN 1
+#  else
+#    define EXPAT_TESTS_UBSAN 0
+#  endif
+#else
+#  define EXPAT_TESTS_UBSAN 0
+#endif
+
 /* Test that XML_ErrorString rejects out-of-range codes */
 START_TEST(test_misc_error_string) {
-  if (XML_ErrorString((enum XML_Error) - 1) != NULL)
+#if ! EXPAT_TESTS_UBSAN // because this would trigger UBSan
+  union {
+    enum XML_Error xml_error;
+    int integer;
+  } trickery;
+
+  assert_true(sizeof(enum XML_Error) == sizeof(int)); // self-test
+
+  trickery.integer = -1;
+  if (XML_ErrorString(trickery.xml_error) != NULL)
     fail("Negative error code not rejected");
-  if (XML_ErrorString((enum XML_Error)100) != NULL)
+
+  trickery.integer = 100;
+  if (XML_ErrorString(trickery.xml_error) != NULL)
     fail("Large error code not rejected");
+#endif
 }
 END_TEST