[libvirt] [PATCH WIP] build: add a warning when configure is executed with -Werror

[Daniel P. Berrange]

On Wed, Sep 19, 2012 at 07:28:02PM -0300, Marcelo Cerri wrote:
> Some tests performed by configure to check what is supported can be
> broken if -Werror is defined in CFLAGS variable when configure is
> executed.
> 
> This patch checks if CFLAGS contains -Werror and shows a warning for
> user recommending to use --enable-compile-warnings=error instead.
> ---
> 
> Please, note that this is a work in progress patch and suggestions are
> welcome.
> 
>  configure.ac | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/configure.ac b/configure.ac
> index 3e90672..38d6263 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -3232,3 +3232,10 @@ AC_MSG_NOTICE([Privileges])
>  AC_MSG_NOTICE([])
>  AC_MSG_NOTICE([      QEMU: $QEMU_USER:$QEMU_GROUP])
>  AC_MSG_NOTICE([])
> +
> +# -Werror can break some configure tests
> +if echo "$CFLAGS" | sed -e 's/\s\+/\n/g' | grep -E '^-Werror$' >/dev/null 2>&1; then
> +    AC_MSG_WARN([CFLAGS contains -Werror flag. This might break some tests performed by])
> +    AC_MSG_WARN([configure and cause some compilation errors.])
> +    AC_MSG_WARN([Please use --enable-compile-warnings=error instead.])
> +fi

Libvirt should not be leaving -Werror set in $CFLAGS - we should only
have it in WARNING_CFLAGS.   Yes, the user might have done something
like  CFLAGS="-Werror" ./configure, but IMHO, they should be letting
libvirt do this, and I don't think should be in the business of trying
to deal with this ourselves.

Daniel
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