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Date: Tue, 10 Mar 2015 13:10:12 -0400
From: John Snow <jsnow@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 1/2] configure: handle clang -nopie
 argument warning
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To: Stefan Hajnoczi <stefanha@redhat.com>, qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>, Peter Maydell <peter.maydell@linaro.org>, Stefan Weil <weil@mail.berlios.de>



On 03/10/2015 08:23 AM, Stefan Hajnoczi wrote:
> gcc 4.9.2 treats -nopie as an error:
>
>    cc: error: unrecognized command line option =E2=80=98-nopie=E2=80=99
>
> clang 3.5.0 treats -nopie as a warning:
>
>    clang: warning: argument unused during compilation: '-nopie'
>
> The causes ./configure to fail with clang:
>
>    ERROR: configure test passed without -Werror but failed with -Werror.
>
> Make the -nopie test use -Werror so that compile_prog works for both gc=
c
> and clang.
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
>   configure | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/configure b/configure
> index 7ba4bcb..4f9f689 100755
> --- a/configure
> +++ b/configure
> @@ -1589,7 +1589,7 @@ EOF
>       fi
>     fi
>
> -  if compile_prog "-fno-pie" "-nopie"; then
> +  if compile_prog "-Werror -fno-pie" "-nopie"; then
>       CFLAGS_NOPIE=3D"-fno-pie"
>       LDFLAGS_NOPIE=3D"-nopie"
>     fi
>

Oh, clang doesn't support -nopie but doesn't fail, so we have to force=20
it to in order to get proper configuration.

Makes sense.

Reviewed-by: John Snow <jsnow@redhat.com>