[OE-core] [PATCH] libunwind: Fix build race conflict with gcc and musl

[Khem Raj]

> On Aug 18, 2016, at 6:46 AM, Richard Purdie <richard.purdie at linuxfoundation.org> wrote:
> 
> Building libunwind, then gcc-runtime causes build failures. This is hard
> to fix since gcc-runtime wants the internal gcc unwind.h header but libunwind
> wants to provide this. There are differences in include behaviour between gcc
> and glibc which are by design.

based upon C library being musl or glibc

> 
> This patch hacks around the issue by looking for a define used during gcc-runtime's
> build and skipping to the internal header in that case. The patch is only enabled
> on musl and is the best workaround I could come up with to unblock failing builds
> on our auto builder.

I also saw gcc build failures not only gcc-runtime. I am not able to find the logs
once I have a reproducer, I will check if it was in libstdc++ as well or elsewhere
nevertheless this is ok to go in.

> 
> [YOCTO #10129]
> 
> Signed-off-by: Richard Purdie <richard.purdie at linuxfoundation.org>
> 
> diff --git a/meta/recipes-support/libunwind/libunwind/musl-header-conflict.patch b/meta/recipes-support/libunwind/libunwind/musl-header-conflict.patch
> new file mode 100644
> index 0000000..79f63fd
> --- /dev/null
> +++ b/meta/recipes-support/libunwind/libunwind/musl-header-conflict.patch
> @@ -0,0 +1,37 @@
> +If you:
> +
> +TCLIBC=musl bitbake unwind
> +TCLIBC=musl bitbake gcc-runtime -c cleansstate
> +TCLIBC=musl bitbake gcc-runtime
> +
> +you will see libstdc++ fail to build due to finding libunwind's header file.
> +
> +Khem: "When we build any of gcc components they expect to use internal version
> +and that works with glibc based gcc since the search headers first look into gcc
> +headers, however with musl the gcc headers are searched after the standard
> +headers ( which is by design the right thing )."
> +
> +This patch hacks around the issue by looking for a define used during gcc-runtime's
> +build and skipping to the internal header in that case.
> +
> +[YOCTO #10129]
> +
> +RP 2016/8/18
> +
> +Upstream-Status: Inappropriate [really need to fix gcc]
> +
> +Index: git/include/unwind.h
> +===================================================================
> +--- git.orig/include/unwind.h
> ++++ git/include/unwind.h
> +@@ -23,6 +23,10 @@ LIABLE FOR ANY CLAIM, DAMAGES OR OTHER L
> + OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
> + WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.  */
> +
> ++#ifdef _GLIBCXX_SHARED
> ++#include_next <unwind.h>
> ++#endif

This is a solution we can live with since _GLIBCXX_SHARED is gcc internal define, it wont
be visible to other packages.

> ++
> + #ifndef _UNWIND_H
> + #define _UNWIND_H
> +
> diff --git a/meta/recipes-support/libunwind/libunwind_git.bb b/meta/recipes-support/libunwind/libunwind_git.bb
> index 6d1d9fb..cd4cb89 100644
> --- a/meta/recipes-support/libunwind/libunwind_git.bb
> +++ b/meta/recipes-support/libunwind/libunwind_git.bb
> @@ -13,6 +13,7 @@ SRC_URI = "git://git.sv.gnu.org/libunwind.git \
>            file://0001-ppc32-Consider-ucontext-mismatches-between-glibc-and.patch \
>            "
> 
> +SRC_URI_append_libc-musl = " file://musl-header-conflict.patch”

It should be fine to use it in general too.

> EXTRA_OECONF_append_libc-musl = " --disable-documentation --disable-tests "
> 
> # http://errors.yoctoproject.org/Errors/Details/20487/
> 
> 

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