[nasm:master] configure: correctly discover -W options for clang

[nasm-bot f. H. P. A. <hp...@zy...>]

Commit-ID:  c9fd7b2aa5086205a626f8312bbaa5043b72a6d7
Gitweb:     http://repo.or.cz/w/nasm.git?a=commitdiff;h=c9fd7b2aa5086205a626f8312bbaa5043b72a6d7
Author:     H. Peter Anvin <hp...@zy...>
AuthorDate: Mon, 16 May 2016 21:35:48 -0700
Committer:  H. Peter Anvin <hp...@zy...>
CommitDate: Mon, 16 May 2016 21:35:48 -0700

configure: correctly discover -W options for clang

clang doesn't error out on unknown -W options unless
-Werror=unknown-warning-option is specified first, so do that so the
configure script can do its job.

Signed-off-by: H. Peter Anvin <hp...@zy...>


---
 configure.in | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/configure.in b/configure.in
index 56e0ce6..61a9f7b 100644
--- a/configure.in
+++ b/configure.in
@@ -183,6 +183,10 @@ AC_ARG_ENABLE([ccache],
 [])
 
 PA_ADD_CFLAGS([-pedantic])
+dnl LLVM doesn't error out on invalid -W options unless this option is
+dnl specified first.  Enable this so this script can actually discover
+dnl which -W options are possible for this compiler.
+PA_ADD_CFLAGS([-Werror=unknown-warning-option])
 dnl Suppress format warning on Windows targets due to their <inttypes.h>
 PA_ADD_CFLAGS([-Wpedantic-ms-format],[-Wno-pedantic-ms-format])
 PA_ADD_CFLAGS([-Wc90-c99-compat])