Re: Problem building Emacs b1fe27d with clang/LLVM 10.x

[Paul Eggert <eggert@cs.ucla.edu>]

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On 5/23/20 12:23 PM, Ashish SHUKLA wrote:

> error: fallthrough annotation does not directly precede switch label

Argh. This appears to be fallout from the C2X draft spec for fallthrough, which
is more restrictive than GCC's (or than Clang 9's, apparently).

> -	  FALLTHROUGH;
>  	resetfvdef:

That patch isn't right, as it causes GCC to warn about the missing FALLTHROUGH.

I installed the attached patch instead, as it should be portable to C2X. Please
give it a try, and thanks for reporting the bug.

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From e021c2dc2279e0fd3a5331f9ea661e4d39c2e840 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sat, 23 May 2020 12:55:13 -0700
Subject: [PATCH] Port etags FALLTHROUGH to C2X

Problem reported by Ashish SHUKLA in:
https://lists.gnu.org/r/emacs-devel/2020-05/msg03013.html
* lib-src/etags.c (C_entries): Move label so that FALLTHROUGH
precedes a case label, as draft C2X specifies.
---
 lib-src/etags.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib-src/etags.c b/lib-src/etags.c
index eee2c59626..4672e3491d 100644
--- a/lib-src/etags.c
+++ b/lib-src/etags.c
@@ -4197,9 +4197,9 @@ C_entries (int c_ext, FILE *inf)
 	      break;
 	    }
 	  FALLTHROUGH;
-	resetfvdef:
 	case '#': case '~': case '&': case '%': case '/':
 	case '|': case '^': case '!': case '.': case '?':
+	resetfvdef:
 	  if (definedef != dnone)
 	    break;
 	  /* These surely cannot follow a function tag in C. */
-- 
2.17.1