configure: Fix building with clang

Building the current code with clang and the latest gnulib fails due to
the use of a variable-length-array (vla) warning, which turns in to an
error due to the presence of the -Werror during the build.

The gnulib team stated that their code should not be built with -Werror.

At present, the only way to do this is for the complete code-base, by
using the --disable-werror option to configure.

Rather than doing this, and failing to gain any benefit that it provides,
instead, if building with clang, this patch makes it possible to specifically
not error on vlas, while retaining the -Werror functionality otherwise.

Signed-off-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

diff --git a/configure.ac b/configure.ac
index 1348b06a985a1c40a6c623c04983dd0f7cc54992..93626b7982d4cd6ee3ed59ecc5c9a4fd33658fd3 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -1939,6 +1939,10 @@ AC_ARG_ENABLE([werror],
 if test x"$enable_werror" != xno ; then
   TARGET_CFLAGS="$TARGET_CFLAGS -Werror"
   HOST_CFLAGS="$HOST_CFLAGS -Werror"
+  if test "x$grub_cv_cc_target_clang" = xyes; then
+    TARGET_CFLAGS="$TARGET_CFLAGS -Wno-error=vla"
+    HOST_CFLAGS="$HOST_CFLAGS -Wno-error=vla"
+  fi
 fi
 
 TARGET_CPP="$TARGET_CC -E"