-Wendif-labels is actually the default.

Has been AFAICT for years / always, the documentation just
had it wrong in pre-4.0 gccs.

diff --git a/cflags.SH b/cflags.SH
index 21f1bbb..abf721f 100755 (executable)
--- a/cflags.SH
+++ b/cflags.SH
@@ -164,7 +164,7 @@ Intel*) ;; # # Is that you, Intel C++?
 # since -std=c89 -pedantic implies the -Werror=...
 *)  for opt in -ansi -std=c89 -W -Wextra \
                -Werror=declaration-after-statement \
-               -Wendif-labels -Wc++-compat -Wwrite-strings
+               -Wc++-compat -Wwrite-strings
     do
        case " $ccflags " in
        *" $opt "*) ;; # Skip if already there.