Re: [Qemu-devel] [RFC] Enable Werrror by default

[Anthony Liguori]

Mark McLoughlin wrote:
> On Thu, 2009-06-11 at 13:35 +0100, Paul Brook wrote:
>
>   
> > I'd like to enable Werror by default. I've been using --enable-werror locally 
> > for a while now, and it's been extremely useful in picking up dumb errors 
> > (like the recent stellaris_enet.c breakage).
> >
> > Any objections?
> >
> > You can of course configure with --disable-werror if you really want the force 
> > things to build.
> >     
>
> Based on experiences with other projects:
>
>   1) Release tarballs should not ship with -Werror on by default - e.g. 
>      new gcc comes along with new warnings and the tarball build fails 
>      with no benefit to anyone
>
>   2) Anyone submitting patches should build with -Werror and make sure 
>      they don't introduce new warnings
>
>   3) People with newer gcc are likely to be tripped up by warnings 
>      introduced by others with older gcc[1]
>
>   4) It's debatable whether builds from git should default to -Werror - 
>      on the plus side it helps ensure (2) happens, on the minus side if 
>      a warning does sneak in, it makes life a pain for everyone until a 
>      fix gets applied
>
> IMHO, we should enable it by default for git builds.
>   
How about the following?  It currently only enables werror for Linux 
hosts and git builds.

Regards,

Anthony Liguori

commit ba59b4615be2b9b989b425bad2499f47a6928d5c
Author: Anthony Liguori <address@hidden>
Date:   Thu Jun 11 13:28:25 2009 -0500

    Enable -Werror by default for git builds on Linux hosts
    
    Additional hosts can be added to the white list as they are confirmed to 
build
    with --enable-werror.
    
    Signed-off-by: Anthony Liguori <address@hidden>

diff --git a/configure b/configure
index 89e7f53..48c8949 100755
--- a/configure
+++ b/configure
@@ -356,11 +356,7 @@ else
 fi
 [ -f "$workdir/vl.c" ] || source_path_used="yes"
 
-werror="no"
-# generate compile errors on warnings for development builds
-#if grep cvs $source_path/VERSION > /dev/null 2>&1 ; then
-#werror="yes";
-#fi
+werror=""
 
 for opt do
   optarg=`expr "x$opt" : 'x[^=]*=\(.*\)'`
@@ -657,6 +653,18 @@ if test ! -x "$(which cgcc 2>/dev/null)"; then
     sparse="no"
 fi
 
+# Consult white-list to determine whether to enable werror
+# by default.  Only enable by default for git builds
+if test -z "$werror" ; then
+    z_version=`cut -f3 -d. $source_path/VERSION`
+    if test "$z_version" = "50" -a \
+       "$linux" = "yes" ; then
+       werror="yes"
+    else
+       werror="no"
+    fi
+fi
+
 #
 # Solaris specific configure tool chain decisions
 #