[Bug gdb/19250] When enabling build-with-cxx, ptrace args type are not detected properly

["cvs-commit at gcc dot gnu.org" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=19250

--- Comment #4 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Pedro Alves <palves@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=9b30624b65697a5f51bb7120c48686ab5506067f

commit 9b30624b65697a5f51bb7120c48686ab5506067f
Author: Pedro Alves <palves@redhat.com>
Date:   Mon Apr 18 17:42:50 2016 +0100

    Fix PR gdb/19250: ptrace prototype is not detected properly in C++ mode

    The ptrace args/return types detection doesn't work properly in C++
    mode, on non-GNU/Linux hosts.  For example, on gcc70 (NetBSD 5.1),
    where the prototype is:

     int ptrace(int, __pid_t, void*, int);

    configure misdetects it as:

     $ grep PTRACE_TYPE config.h
     #define PTRACE_TYPE_ARG1 int
     #define PTRACE_TYPE_ARG3 int *
     #define PTRACE_TYPE_ARG4 int
     /* #undef PTRACE_TYPE_ARG5 */
     #define PTRACE_TYPE_RET int

    resulting in:

     ../../src/gdb/amd64bsd-nat.c: In function 'void
amd64bsd_fetch_inferior_registers(target_ops*, regcache*, int)':
     ../../src/gdb/amd64bsd-nat.c:56: warning: dereferencing type-punned
pointer will break strict-aliasing rules
     ../../src/gdb/amd64bsd-nat.c: In function 'void
amd64bsd_store_inferior_registers(target_ops*, regcache*, int)':
     ../../src/gdb/amd64bsd-nat.c:104: warning: dereferencing type-punned
pointer will break strict-aliasing rules
     ../../src/gdb/amd64bsd-nat.c:110: warning: dereferencing type-punned
pointer will break strict-aliasing rules

    We could address this [1], however despite ptrace.m4's claim:

     # Needs to be tested in C++ mode, to detect whether we need to cast
     # the first argument to enum __ptrace_request.

    it appears that there's actually no need to test in C++ mode.  Always
    running the ptrace tests in C mode works just the same on GNU/Linux.

    I remember experimenting with several different ways to handle the
    original issue back then, and maybe that was needed in some other
    attempt and then I didn't realize it ended up not really necessary.

    Confirmed that this fixes the NetBSD 5.1 C++ build, and confirmed that
    C and C++ builds on Fedora 23 are unaffected.

    [1] - https://sourceware.org/ml/gdb-patches/2016-04/msg00374.html

    gdb/ChangeLog:
    2016-04-18  Pedro Alves  <palves@redhat.com>

        * ptrace.m4 (GDB_AC_PTRACE): Don't run tests in C++ mode.
        * configure: Regenerate.

    gdb/gdbserver/ChangeLog:
    2016-04-18  Pedro Alves  <palves@redhat.com>

        * configure: Regenerate.

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