[Bug tui/31399] New: Build fails on macOS: error: cannot cast 'tui_win_info *' to 'tui_cmd_window *' via virtual base 'tui_win_info'

[Bug tui/31399] New: Build fails on macOS: error: cannot cast 'tui_win_info *' to 'tui_cmd_window *' via virtual base 'tui_win_info'

[spam_hole at shaw dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=31399

            Bug ID: 31399
           Summary: Build fails on macOS: error: cannot cast 'tui_win_info
                    *' to 'tui_cmd_window *' via virtual base
                    'tui_win_info'
           Product: gdb
           Version: HEAD
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: tui
          Assignee: unassigned at sourceware dot org
          Reporter: spam_hole at shaw dot ca
  Target Milestone: ---

Building binutils+gdb from binutils-2.42 source fails with the following error:

======== 8< ========
In file included from ../../gdb/tui/tui-command.c:24:
In file included from ../../gdb/tui/tui-data.h:28:
../../gdb/../gdbsupport/gdb-checked-static-cast.h:63:14: error: cannot cast
'tui_win_info *' to 'tui_cmd_window *' via virtual base 'tui_win_info'
  T result = static_cast<T> (v);
             ^~~~~~~~~~~~~~~~~~
../../gdb/tui/tui-command.c:65:15: note: in instantiation of function template
specialization 'gdb::checked_static_cast<tui_cmd_window *, tui_win_info>'
requested here
  WINDOW *w = TUI_CMD_WIN->handle.get ();
              ^
../../gdb/tui/tui-data.h:299:9: note: expanded from macro 'TUI_CMD_WIN'
  (gdb::checked_static_cast<tui_cmd_window *> (tui_win_list[CMD_WIN]))
        ^
1 error generated.
======== 8< ========

Build fails with Apple clang version 15.0.0 (clang-1500.1.0.2.5) on macOS
13.6.1 (22G313).

This is a regression apparently originating in commit
85a427b26c5cae6af6ed0b4358d44a77b5a3b2c0
(https://git.libre-soc.org/?p=binutils-gdb.git;a=commit;h=85a427b26c5cae6af6ed0b4358d44a77b5a3b2c0).
I believe dynamic_cast is needed instead of static_cast.

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[Bug tui/31399] Build fails on macOS: error: cannot cast 'tui_win_info *' to 'tui_cmd_window *' via virtual base 'tui_win_info'

[ssbssa at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31399

Hannes Domani <ssbssa at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ssbssa at sourceware dot org

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[Bug build/31399] Build fails on macOS: error: cannot cast 'tui_win_info *' to 'tui_cmd_window *' via virtual base 'tui_win_info'

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31399

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vries at gcc dot gnu.org
          Component|tui                         |build

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[Bug build/31399] Build fails on macOS: error: cannot cast 'tui_win_info *' to 'tui_cmd_window *' via virtual base 'tui_win_info'

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31399

--- Comment #1 from Tom de Vries <vries at gcc dot gnu.org> ---
https://sourceware.org/pipermail/gdb-patches/2024-February/206767.html

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[Bug build/31399] Build fails on macOS: error: cannot cast 'tui_win_info *' to 'tui_cmd_window *' via virtual base 'tui_win_info'

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31399

--- Comment #2 from Sourceware Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tom de Vries <vries@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=6fe4779ac4b1874c995345e3eabd89cb1a05fbdf

commit 6fe4779ac4b1874c995345e3eabd89cb1a05fbdf
Author: Tom de Vries <tdevries@suse.de>
Date:   Sat Feb 24 11:00:20 2024 +0100

    [gdb/build] Fix static cast of virtual base

    With this change in bfd/development.sh:
    ...
    -development=true
    +development=false
    ...
    we run into:
    ...
    In file included from tui-data.h:28:0,
                     from tui-command.c:24:
    gdb-checked-static-cast.h: In instantiation of \
      âT gdb::checked_static_cast(V*) [with T = tui_cmd_window*; V =
tui_win_info]â:
    tui-command.c:65:15:   required from here
    gdb-checked-static-cast.h:63:14: error: cannot convert from pointer to base
\
      class âtui_win_infoâ to pointer to derived class âtui_cmd_windowâ
because \
      the base is virtual
       T result = static_cast<T> (v);
                  ^~~~~~~~~~~~~~~~~~
    ...

    Fix this by using dynamic_cast instead of gdb::checked_static_cast in
    TUI_CMD_WIN and TUI_STATUS_WIN.

    Tested on x86_64-linux, with development set to false.

    Reported-By: Robert Xiao <spam_hole@shaw.ca>
    Reported-By: Simon Marchi <simark@simark.ca>
    Approved-By: Tom Tromey <tom@tromey.com>

    PR build/31399
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31399

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[Bug build/31399] Build fails on macOS: error: cannot cast 'tui_win_info *' to 'tui_cmd_window *' via virtual base 'tui_win_info'

[vries at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31399

Tom de Vries <vries at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
   Target Milestone|---                         |15.1
         Resolution|---                         |FIXED

--- Comment #3 from Tom de Vries <vries at gcc dot gnu.org> ---
Fixed.

Thanks for reporting this.

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[Bug build/31399] Build fails on macOS: error: cannot cast 'tui_win_info *' to 'tui_cmd_window *' via virtual base 'tui_win_info'

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=31399

--- Comment #4 from Sourceware Commits <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=7d18eb9983b00455fd2f3100d4de2772c3f656ad

commit 7d18eb9983b00455fd2f3100d4de2772c3f656ad
Author: Andrew Burgess <aburgess@redhat.com>
Date:   Wed Mar 6 17:28:48 2024 +0000

    gdb: use static_cast in gdb::checked_static_cast

    This commit:

      commit 6fe4779ac4b1874c995345e3eabd89cb1a05fbdf
      Date:   Sat Feb 24 11:00:20 2024 +0100

          [gdb/build] Fix static cast of virtual base

    addressed an issue where GDB would not compile in production mode due
    to a use of gdb::checked_static_cast.  The problem was that we were
    asking GDB to cast from a virtual base class to a sub-class, this
    works fine when using dynamic_cast, but does not work with
    static_cast.

    The gdb::checked_static_cast actually uses dynamic_cast under the hood
    in development mode in order to ensure that the cast is valid, while
    in a production build we use static_cast as this is more efficient.

    What this meant however, was that when gdb::checked_static_cast was
    used to cast from a virtual base class, the dynamic_cast of a
    non-production build worked fine, while the production build's
    static_cast caused a build failure.

    However, the gdb::checked_static_cast function already contains some
    static_assert calls that are intended to catch any issues with invalid
    type casting, the goal of these asserts was to prevent issues like
    this: the build only failing in production mode.  Clearly the current
    asserts are not enough.

    I don't think there is a std::is_virtual_base type trait check, so
    what I propose instead is that in non-production mode we also make use
    of static_cast.  This will ensure that any errors that crop up in
    production mode should also be revealed in non-production mode, and
    should catch issues like this in the future.

    There should be no user visible changes after this commit.

    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=31399

    Co-Authored-By: Simon Marchi <simon.marchi@polymtl.ca>

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