From 080044c7f2754684b37b9abc5d862d3f9757f893 Mon Sep 17 00:00:00 2001
From: Yannis Guyon <yguyon@google.com>
Date: Thu, 9 Apr 2026 08:58:49 +0000
Subject: [PATCH] Replace [[fallthrough]] with WEBP_FALLTHROUGH

C and C++ version values based on
https://en.cppreference.com/w/c/23.html and
https://en.cppreference.com/w/cpp/preprocessor/replace.

Change-Id: I1059fa9e17f25f05d452f8dd003ca7d421742bf7
---
 examples/webpmux.c | 12 +++++++++---
 src/webp/types.h   |  9 +++++++++
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/examples/webpmux.c b/examples/webpmux.c
index 8f32914d..d5c71af6 100644
--- a/examples/webpmux.c
+++ b/examples/webpmux.c
@@ -493,12 +493,18 @@ static int ParseFrameArgs(const char* args, WebPMuxFrameInfo* const info) {
                               &plus_minus, &blend_method, &unused);
   switch (num_args) {
     case 1:
-      info->x_offset = info->y_offset = 0;  // fall through
+      info->x_offset = info->y_offset = 0;
+      WEBP_FALLTHROUGH;
+      // fall through
     case 3:
-      dispose_method = 0;  // fall through
+      dispose_method = 0;
+      WEBP_FALLTHROUGH;
+      // fall through
     case 4:
       plus_minus = '+';
-      blend_method = 'b';  // fall through
+      blend_method = 'b';
+      WEBP_FALLTHROUGH;
+      // fall through
     case 6:
       break;
     case 2:
diff --git a/src/webp/types.h b/src/webp/types.h
index 9521c863..8b086a1c 100644
--- a/src/webp/types.h
+++ b/src/webp/types.h
@@ -71,6 +71,15 @@ typedef long long int int64_t;
 #endif /* defined(_WIN32) && defined(WEBP_DLL) */
 #endif /* WEBP_EXTERN */
 
+#ifndef WEBP_FALLTHROUGH
+#if (defined(__cplusplus) && __cplusplus >= 201703L) || \
+    (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 202311L)
+#define WEBP_FALLTHROUGH [[fallthrough]]
+#else
+#define WEBP_FALLTHROUGH
+#endif
+#endif /* WEBP_FALLTHROUGH */
+
 // Macro to check ABI compatibility (same major revision number)
 #define WEBP_ABI_IS_INCOMPATIBLE(a, b) (((a) >> 8) != ((b) >> 8))