From 75affc8f555f8b757834e156abdba7331cfe71dd Mon Sep 17 00:00:00 2001
From: Nicolas Williams <nico@twosigma.com>
Date: Mon, 5 Jan 2026 19:05:23 -0600
Subject: [PATCH] cf: clang pretends to be GCC 4

---
 configure.ac | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/configure.ac b/configure.ac
index a38bbff84..be9f02e91 100644
--- a/configure.ac
+++ b/configure.ac
@@ -547,16 +547,13 @@ dnl Deal with switch fallthrough warnings
 AH_TOP([
 #if defined(DISPATCH_FALLTHROUGH)
 # define HEIM_FALLTHROUGH DISPATCH_FALLTHROUGH
+#elif defined(__clang__)
+  /* Clang sets __GNUC__ to 4 for compat, but supports fallthrough attr */
+# define HEIM_FALLTHROUGH __attribute__((fallthrough))
+#elif defined(__GNUC__) && __GNUC__ >= 7
+# define HEIM_FALLTHROUGH __attribute__((fallthrough))
 #else
-# if defined(__GNUC__)
-#  if __GNUC__ >= 7
-#   define HEIM_FALLTHROUGH __attribute__((fallthrough))
-#  else
-#   define HEIM_FALLTHROUGH do {} while (0) /* fallthrough */
-#  endif
-# else
-#  define HEIM_FALLTHROUGH do {} while (0) /* fallthrough */
-# endif
+# define HEIM_FALLTHROUGH do {} while (0) /* fallthrough */
 #endif
 ])