Hi,

emacs compilation with clang10 on Ubuntu 20.04 (focal release) fails with an error in the file lib-src/etags.c. I am able to fix the issue with a one-line change. This compilation failure is seen on the emacs src from top-of-the-master-branch.

Pls see if this fix is appropriate and consider accordingly.

I have given below the details on the issue and a patch description.

Regards

Narayanan

clang --version
clang version 10.0.0-4ubuntu1
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

make -C lib-src all
make[1]: Entering directory '/mnt/myvg_fs/home/anarayan/sources/emacs/lib-src'
CCLD etags
error: fallthrough annotation does not directly precede switch label
1 error generated.
make[1]: *** [Makefile:366: etags] Error 1
make[1]: Leaving directory '/mnt/myvg_fs/home/anarayan/sources/emacs/lib-src'
make: *** [Makefile:411: lib-src] Error 2

diff --git a/lib-src/etags.c b/lib-src/etags.c
index eee2c59626..b5f077007b 100644
--- a/lib-src/etags.c
+++ b/lib-src/etags.c
@@ -4196,7 +4196,7 @@ C_entries (int c_ext, FILE *inf)
objdef = omethodsign;
break;
}
- FALLTHROUGH;
+ // FALLTHROUGH;
resetfvdef:
case '#': case '~': case '&': case '%': case '/':
case '|': case '^': case '!': case '.': case '?':