Re: [PATCH] libvirt: disable Werror for non-libvirt flights

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Tue, Sep 13, 2022 at 12:03:28PM +0200, Roger Pau Monne wrote:
> Current usage of Werror=switch-enum by default for libvirt builds out
> of the git tree causes issues when new items are added to libxl public
> API enums if those are used in a switch statement in libvirt code.
> This leads to libvirt build failures for seemingly unrelated libxl
> changes.
> 
> In order to prevent those errors from blocking the push gate, disable
> Werror for libvirt builds when not in a libvirt specific flight.
> 
> The errors will be reported on the libvirt flight, and block the
> pushes there.  So the author of the changes in libxl is still expected
> to send a fix to libvirt code.  This is no ideal, but the other option
> is to just disable Werror for all libvirt builds and let libvirt
> developers fix the breakage when they notice it.
> 
> runvar differences for a xen-unstable flight are:
> 
> --- /dev/fd/63  2022-09-13 09:53:58.044441678 +0000
> +++ /dev/fd/62  2022-09-13 09:53:58.044441678 +0000
> @@ -574,6 +574,10 @@
>  test-xtf-amd64-amd64-3                                arch                   
>          amd64
>  test-xtf-amd64-amd64-4                                arch                   
>          amd64
>  test-xtf-amd64-amd64-5                                arch                   
>          amd64
> +build-amd64-libvirt                                   autogen_options        
>          --disable-werror
> +build-arm64-libvirt                                   autogen_options        
>          --disable-werror
> +build-armhf-libvirt                                   autogen_options        
>          --disable-werror
> +build-i386-libvirt                                    autogen_options        
>          --disable-werror
>  test-amd64-amd64-libvirt-qemuu-debianhvm-amd64-xsm    bios                   
>          seabios
>  test-amd64-amd64-qemuu-nested-amd                     bios                   
>          seabios
>  test-amd64-amd64-qemuu-nested-intel                   bios                   
>          seabios
> @@ -1217,6 +1221,10 @@
>  build-arm64-libvirt                                   make_njobs             
>          1
>  build-armhf-libvirt                                   make_njobs             
>          1
>  build-i386-libvirt                                    make_njobs             
>          1
> +build-amd64-libvirt                                   meson_options          
>          -Dgit_werror=disabled
> +build-arm64-libvirt                                   meson_options          
>          -Dgit_werror=disabled
> +build-armhf-libvirt                                   meson_options          
>          -Dgit_werror=disabled
> +build-i386-libvirt                                    meson_options          
>          -Dgit_werror=disabled
>  test-amd64-amd64-xl-qemuu-dmrestrict-amd64-dmrestrict recipe_dmrestrict      
>          true
>  test-amd64-i386-xl-qemuu-dmrestrict-amd64-dmrestrict  recipe_dmrestrict      
>          true
>  test-amd64-amd64-xl-qemuu-dmrestrict-amd64-dmrestrict recipe_nomigrate       
>          true

For "osstest" flight or "xen-unstable-smoke" flight, we would have the
same difference, right?

The only branch with no change would be libvirt, right?

> 
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> ---
> I'm unsure whether we want o disable Werror even for libvirt flights,
> but this seems more conservative.
> 
> This does at least unblock the libvirt builds for both the
> xen-unstable and the libvirt flights.
> ---
> Cc: Ian Jackson <iwj@xxxxxxxxxxxxxx>
> Cc: Anthony PERARD <anthony.perard@xxxxxxxxxx>
> Cc: Julien Grall <julien@xxxxxxx>
> ---
>  mfi-common       | 2 +-
>  ts-libvirt-build | 3 ++-
>  2 files changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/mfi-common b/mfi-common
> index 59e712f4..450229e9 100644
> --- a/mfi-common
> +++ b/mfi-common
> @@ -459,7 +459,7 @@ create_build_jobs () {
>      libvirt_build_runvars=''
>      case "$branch" in
>      libvirt*) ;;
> -    *)        libvirt_build_runvars+=" make_njobs=1";;
> +    *)        libvirt_build_runvars+=" make_njobs=1 
> meson_options=-Dgit_werror=disabled autogen_options=--disable-werror";;

For meson, I think '-Dwerror=false' would be enough, instead of the
unusual 'git_werror' configuration.

But, we might not need to disable all errors, for meson we can have:
    -Dc_args='-Wno-error=switch -Wno-error=switch-enum'

But disabling werror is fine too, as less likely to be an issue later.

Both 'werror' and 'c_args' seems to be meson built-in options rather
than options implemented for only libvirt.
    https://mesonbuild.com/Builtin-options.html
While 'git_werror' is libvirt only.


Thanks,

-- 
Anthony PERARD