[Bug python/29712] [gdb, aarch64] UNRESOLVED: gdb.python/py-disasm.exp: global_disassembler=ReadMemoryGdbErrorDisassembler: disassemble test

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

https://sourceware.org/bugzilla/show_bug.cgi?id=29712

--- Comment #12 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Andrew Burgess <aburgess@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=8eb7d135e32ad6b7cdcfeffe486b195058206cdb

commit 8eb7d135e32ad6b7cdcfeffe486b195058206cdb
Author: Andrew Burgess <aburgess@redhat.com>
Date:   Mon Oct 24 18:35:41 2022 +0100

    gdb/disasm: mark functions passed to the disassembler noexcept

    While working on another patch, Simon pointed out that GDB could be
    improved by marking the functions passed to the disassembler as
    noexcept.

      https://sourceware.org/pipermail/gdb-patches/2022-October/193084.html

    The reason this is important is the on some hosts, libopcodes, being C
    code, will not be compiled with support for handling exceptions.  As
    such, an attempt to throw an exception over libopcodes code will cause
    GDB to terminate.

    See bug gdb/29712 for an example of when this happened.

    In this commit all the functions that are passed to the disassembler,
    and which might be used as callbacks by libopcodes are marked
    noexcept.

    Ideally, I would have liked to change these typedefs:

      using read_memory_ftype = decltype (disassemble_info::read_memory_func);
      using memory_error_ftype = decltype
(disassemble_info::memory_error_func);
      using print_address_ftype = decltype
(disassemble_info::print_address_func);
      using fprintf_ftype = decltype (disassemble_info::fprintf_func);
      using fprintf_styled_ftype = decltype
(disassemble_info::fprintf_styled_func);

    which are declared in disasm.h, as including the noexcept keyword.
    However, when I tried this, I ran into this warning/error:

      In file included from ../../src/gdb/disasm.c:25:
      ../../src/gdb/disasm.h: In constructor
âgdb_printing_disassembler::gdb_printing_disassembler(gdbarch*, ui_file*,
gdb_disassemble_info::read_memory_ftype,
gdb_disassemble_info::memory_error_ftype,
gdb_disassemble_info::print_address_ftype)â:
      ../../src/gdb/disasm.h:116:3: error: mangled name for
âgdb_printing_disassembler::gdb_printing_disassembler(gdbarch*, ui_file*,
gdb_disassemble_info::read_memory_ftype,
gdb_disassemble_info::memory_error_ftype,
gdb_disassemble_info::print_address_ftype)â will change in C++17 because the
exception specification is part of a function type [-Werror=noexcept-type]
        116 |   gdb_printing_disassembler (struct gdbarch *gdbarch,
            |   ^~~~~~~~~~~~~~~~~~~~~~~~~

    So I've left that change out.  This does mean that if somebody adds a
    new use of the disassembler classes in the future, and forgets to mark
    the callbacks as noexcept, this will compile fine.  We'll just have to
    manually check for that during review.

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