From 7e2b7da3d6568d2e4e78658f22e701746a48d7e1 Mon Sep 17 00:00:00 2001
From: Ian Lance Taylor <iant@golang.org>
Date: Thu, 18 Jul 2024 11:34:09 -0700
Subject: [PATCH] libbacktrace: use __has_attribute for fallthrough

Also convert some FALLTHROUGH comments to ATTRIBUTE_FALLTHROUGH.

	* internal.h: Use __has_attribute to check for fallthrough
	attribute.
	* elf.c (elf_zstd_decompress): Use ATTRIBUTE_FALLTHROUGH rather
	than a FALLTHROUGH comment.
---
 elf.c      | 14 +++++++-------
 internal.h |  5 +++++
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/elf.c b/elf.c
index e8d67fe..0040479 100644
--- a/elf.c
+++ b/elf.c
@@ -4848,25 +4848,25 @@ elf_zstd_decompress (const unsigned char *pin, size_t sin,
 		  {
 		  case 8:
 		    *pout++ = *plit++;
-		    /* FALLTHROUGH */
+		    ATTRIBUTE_FALLTHROUGH;
 		  case 7:
 		    *pout++ = *plit++;
-		    /* FALLTHROUGH */
+		    ATTRIBUTE_FALLTHROUGH;
 		  case 6:
 		    *pout++ = *plit++;
-		    /* FALLTHROUGH */
+		    ATTRIBUTE_FALLTHROUGH;
 		  case 5:
 		    *pout++ = *plit++;
-		    /* FALLTHROUGH */
+		    ATTRIBUTE_FALLTHROUGH;
 		  case 4:
 		    *pout++ = *plit++;
-		    /* FALLTHROUGH */
+		    ATTRIBUTE_FALLTHROUGH;
 		  case 3:
 		    *pout++ = *plit++;
-		    /* FALLTHROUGH */
+		    ATTRIBUTE_FALLTHROUGH;
 		  case 2:
 		    *pout++ = *plit++;
-		    /* FALLTHROUGH */
+		    ATTRIBUTE_FALLTHROUGH;
 		  case 1:
 		    *pout++ = *plit++;
 		    break;
diff --git a/internal.h b/internal.h
index a119cda..fe2abe5 100644
--- a/internal.h
+++ b/internal.h
@@ -56,6 +56,11 @@ POSSIBILITY OF SUCH DAMAGE.  */
 # endif
 #endif
 
+#ifdef __has_attribute
+# if __has_attribute(fallthrough)
+#  define ATTRIBUTE_FALLTHROUGH __attribute__ ((fallthrough))
+# endif
+#endif
 #ifndef ATTRIBUTE_FALLTHROUGH
 # if (GCC_VERSION >= 7000)
 #  define ATTRIBUTE_FALLTHROUGH __attribute__ ((__fallthrough__))