Note for gofrontend-dev: on gcc-patches only Andreas Schwab suggested
using uc_regs instead of regs, which does look correct to me.

Ian

On Mon, Feb 21, 2022 at 8:47 AM Sören Tempel <soe...@soeren-tempel.net> wrote:
>
> Ping.
>
> Summary: Fix build of libgo on PPC with musl libc and libucontext by
> explicitly including the Linux header defining `struct pt_regs` instead of
> relying on other libc headers to include it implicitly.
>
> See: https://gcc.gnu.org/pipermail/gcc-patches/2022-January/587520.html
>
> If the patch needs to be revised further please let me know. This patch has
> been applied at Alpine Linux downstream (which uses musl libc) for a while, I
> have not tested it on other systems.
>
> Greetings,
> Sören
>
> Sören Tempel <soe...@soeren-tempel.net> wrote:
> > Both glibc and musl libc declare pt_regs as an incomplete type. This
> > type has to be completed by inclusion of another header. On Linux, the
> > asm/ptrace.h header file provides this type definition. Without
> > including this header file, it is not possible to access the regs member
> > of the mcontext_t struct as done in libgo/runtime/go-signal.c. On glibc,
> > other headers (e.g. sys/user.h) include asm/ptrace.h but on musl
> > asm/ptrace.h is not included by other headers and thus the
> > aforementioned files do not compile without an explicit include of
> > asm/ptrace.h:
> >
> >       libgo/runtime/go-signal.c: In function 'getSiginfo':
> >       libgo/runtime/go-signal.c:227:63: error: invalid use of undefined 
> > type 'struct pt_regs'
> >         227 |         ret.sigpc = 
> > ((ucontext_t*)(context))->uc_mcontext.regs->nip;
> >             |
> >
> > See also:
> >
> > * 
> > https://git.musl-libc.org/cgit/musl/commit/?id=c2518a8efb6507f1b41c3b12e03b06f8f2317a1f
> > * https://github.com/kaniini/libucontext/issues/36
> >
> > Signed-off-by: Sören Tempel <soe...@soeren-tempel.net>
> >
> > ChangeLog:
> >
> >       * libgo/runtime/go-signal.c: Include asm/ptrace.h for the
> >         definition of pt_regs (used by mcontext_t) on PowerPC.
> > ---
> >  libgo/runtime/go-signal.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/libgo/runtime/go-signal.c b/libgo/runtime/go-signal.c
> > index d30d1603adc..fc01e04e4a1 100644
> > --- a/libgo/runtime/go-signal.c
> > +++ b/libgo/runtime/go-signal.c
> > @@ -10,6 +10,12 @@
> >  #include <sys/time.h>
> >  #include <ucontext.h>
> >
> > +// On PowerPC, ucontext.h uses a pt_regs struct as an incomplete
> > +// type. This type must be completed by including asm/ptrace.h.
> > +#ifdef __PPC__
> > +#include <asm/ptrace.h>
> > +#endif
> > +
> >  #include "runtime.h"
> >
> >  #ifndef SA_RESTART
>
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