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Re: [Qemu-devel] [PATCH v2] configure: Make epoll_create1 test work arou
From: |
Blue Swirl |
Subject: |
Re: [Qemu-devel] [PATCH v2] configure: Make epoll_create1 test work around SPARC glibc bug |
Date: |
Tue, 26 Apr 2011 23:08:58 +0300 |
Thanks, applied.
On Tue, Apr 26, 2011 at 6:56 PM, Peter Maydell <address@hidden> wrote:
> Work around a SPARC glibc bug which caused the epoll_create1 configure
> test to wrongly claim that the function was present. Some versions of
> SPARC glibc provided the function in the library but didn't declare
> it in the include file; the result is that gcc warns about an implicit
> declaration but a link succeeds. So we reference the function as a
> value rather than a function call to induce a compile time error
> if the declaration was not present.
>
> Signed-off-by: Peter Maydell <address@hidden>
> ---
> v1->v2: instead of compiling the test with -Werror, use the approach
> suggested by Blue Swirl to force a compile-time failure if the
> declaration is missing from the header file.
>
> configure | 10 +++++++++-
> 1 files changed, 9 insertions(+), 1 deletions(-)
>
> diff --git a/configure b/configure
> index de44bac..2bbbbf5 100755
> --- a/configure
> +++ b/configure
> @@ -2225,7 +2225,15 @@ cat > $TMPC << EOF
>
> int main(void)
> {
> - epoll_create1(0);
> + /* Note that we use epoll_create1 as a value, not as
> + * a function being called. This is necessary so that on
> + * old SPARC glibc versions where the function was present in
> + * the library but not declared in the header file we will
> + * fail the configure check. (Otherwise we will get a compiler
> + * warning but not an error, and will proceed to fail the
> + * qemu compile where we compile with -Werror.)
> + */
> + epoll_create1;
> return 0;
> }
> EOF
> --
> 1.7.1
>
>