[Bug libstdc++/97362] New: __deref in <functional> in debug mode clashes with Windows SDK internal macro

[Bug libstdc++/97362] New: __deref in <functional> in debug mode clashes with Windows SDK internal macro

[frankhb1989 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97362

            Bug ID: 97362
           Summary: __deref in <functional> in debug mode clashes with
                    Windows SDK internal macro
           Product: gcc
           Version: 10.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: frankhb1989 at gmail dot com
  Target Milestone: ---

Case:

#include <windows.h>
#include <functional>

int main()
{}

/tmp $ g++ -D_GLIBCXX_DEBUG a.cc
In file included from F:/msys64/mingw64/include/c++/10.2.0/debug/debug.h:133,
                 from
F:/msys64/mingw64/include/c++/10.2.0/bits/stl_algobase.h:69,
                 from F:/msys64/mingw64/include/c++/10.2.0/array:40,
                 from F:/msys64/mingw64/include/c++/10.2.0/tuple:39,
                 from F:/msys64/mingw64/include/c++/10.2.0/functional:54,
                 from a.cc:2:
F:/msys64/mingw64/include/c++/10.2.0/debug/functions.h:424:15: error: expected
unqualified-id before ')' token
  424 |       __deref();
      |               ^
F:/msys64/mingw64/include/c++/10.2.0/debug/functions.h:427:34: error: expected
primary-expression before '<' token
  427 |       typename = decltype(__deref<_It>() < __deref<_It>())>
      |                                  ^
F:/msys64/mingw64/include/c++/10.2.0/debug/functions.h:427:38: error: expected
primary-expression before '>' token
  427 |       typename = decltype(__deref<_It>() < __deref<_It>())>
      |                                      ^
F:/msys64/mingw64/include/c++/10.2.0/debug/functions.h:427:40: error: expected
primary-expression before ')' token
  427 |       typename = decltype(__deref<_It>() < __deref<_It>())>
      |                                        ^
F:/msys64/mingw64/include/c++/10.2.0/debug/functions.h:427:51: error: expected
primary-expression before '<' token
  427 |       typename = decltype(__deref<_It>() < __deref<_It>())>
      |                                                   ^
F:/msys64/mingw64/include/c++/10.2.0/debug/functions.h:427:55: error: expected
primary-expression before '>' token
  427 |       typename = decltype(__deref<_It>() < __deref<_It>())>
      |                                                       ^
F:/msys64/mingw64/include/c++/10.2.0/debug/functions.h:427:57: error: expected
primary-expression before ')' token
  427 |       typename = decltype(__deref<_It>() < __deref<_It>())>
      |                                                         ^
F:/msys64/mingw64/include/c++/10.2.0/debug/functions.h:441:42: error: expected
primary-expression before '<' token
  441 |  = decltype(std::declval<_Pred>()(__deref<_It>(), __deref<_It>()))>
      |                                          ^
F:/msys64/mingw64/include/c++/10.2.0/debug/functions.h:441:46: error: expected
primary-expression before '>' token
  441 |  = decltype(std::declval<_Pred>()(__deref<_It>(), __deref<_It>()))>
      |                                              ^
F:/msys64/mingw64/include/c++/10.2.0/debug/functions.h:441:48: error: expected
primary-expression before ')' token
  441 |  = decltype(std::declval<_Pred>()(__deref<_It>(), __deref<_It>()))>
      |                                                ^
F:/msys64/mingw64/include/c++/10.2.0/debug/functions.h:441:58: error: expected
primary-expression before '<' token
  441 |  = decltype(std::declval<_Pred>()(__deref<_It>(), __deref<_It>()))>
      |                                                          ^
F:/msys64/mingw64/include/c++/10.2.0/debug/functions.h:441:62: error: expected
primary-expression before '>' token
  441 |  = decltype(std::declval<_Pred>()(__deref<_It>(), __deref<_It>()))>
      |                                                              ^
F:/msys64/mingw64/include/c++/10.2.0/debug/functions.h:441:64: error: expected
primary-expression before ')' token
  441 |  = decltype(std::declval<_Pred>()(__deref<_It>(), __deref<_It>()))>

This is reproducible with MSYS2's {i686, x86_64}-w64-mingw32-g++. Note it
compiles without -D_GLIBCXX_DEBUG.

The offending `__deref` is from WinSDK header <sal.h> (also available in
mingw-w64 for compatibility). As a system header, it is legitimate to have
reserved identifiers. Although the workaround is simple (by #undef, since
<specstrings_undef.h> is not available in mingw-w64 yet), it is still annoying
and confusing. It seems a quick workaround by avoiding using `__deref` here is
more appropriate.

[Bug libstdc++/97362] `__deref` in <functional> in debug mode clashes with internal macro in Windows system header

[frankhb1989 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97362

--- Comment #1 from frankhb1989 at gmail dot com ---
To clarify a bit: <sal.h> is installed by the VC++ toolchain or WDK, not by
Windows SDK. Nevertheless, it is a system header both MS's CRT and Win32
headers rely on.

[Bug libstdc++/97362] [8/9/10/11 Regression] `__deref` in <functional> in debug mode clashes with internal macro in Windows system header

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97362

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|`__deref` in <functional>   |[8/9/10/11 Regression]
                   |in debug mode clashes with  |`__deref` in <functional>
                   |internal macro in Windows   |in debug mode clashes with
                   |system header               |internal macro in Windows
                   |                            |system header
      Known to fail|                            |10.2.0, 11.0, 6.1.0, 7.5.0,
                   |                            |8.4.0, 9.3.0
     Ever confirmed|0                           |1
           Keywords|                            |rejects-valid
   Last reconfirmed|                            |2020-10-10
           Priority|P3                          |P2
                 CC|                            |fdumont at gcc dot gnu.org
   Target Milestone|---                         |8.5
             Status|UNCONFIRMED                 |NEW
      Known to work|                            |5.5.0

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Added with r227189 for PR libstdc++/60519

Let's just rename it.

[Bug libstdc++/97362] [8/9/10/11 Regression] `__deref` in <functional> in debug mode clashes with internal macro in Windows system header

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97362

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
And add __deref to the list of BADNAMES in
doc/xml/manual/appendix_contributing.xml and the
testsuite/17_intro/headers/names.cc test.

[Bug libstdc++/97362] [8/9/10/11 Regression] `__deref` in <functional> in debug mode clashes with internal macro in Windows system header

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97362

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to frankhb1989 from comment #0)
> Case:
> 
> #include <windows.h>
> #include <functional>

N.B. this has nothing to do with <functional>. The __deref entity is in
<debug/functions.h> which gets included by <algorithm> and all the containers
(and a few other places). <functional> just happens to include <array> which
uses the debug mode header.

[Bug libstdc++/97362] [8/9/10/11 Regression] `__deref` in <functional> in debug mode clashes with internal macro in Windows system header

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97362

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |redi at gcc dot gnu.org
             Status|NEW                         |ASSIGNED

[Bug libstdc++/97362] [8/9/10 Regression] `__deref` in <functional> in debug mode clashes with internal macro in Windows system header

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97362

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[8/9/10/11 Regression]      |[8/9/10 Regression]
                   |`__deref` in <functional>   |`__deref` in <functional>
                   |in debug mode clashes with  |in debug mode clashes with
                   |internal macro in Windows   |internal macro in Windows
                   |system header               |system header
      Known to fail|11.0                        |

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Fixed on trunk with g:2137aa92412da363d52ef699987441be28b239d0 which for some
reason didn't get added here.

[Bug libstdc++/97362] [8/9/10 Regression] `__deref` in <functional> in debug mode clashes with internal macro in Windows system header

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97362

--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to frankhb1989 from comment #1)
> To clarify a bit: <sal.h> is installed by the VC++ toolchain or WDK, not by
> Windows SDK. Nevertheless, it is a system header both MS's CRT and Win32
> headers rely on.

I can't reproduce this, as I don't see the __deref macro in the mingw-w64
headers.

Does this only happen with the Microsoft headers, not mingw versions? Or
something else?

[Bug libstdc++/97362] [8/9/10 Regression] `__deref` in <functional> in debug mode clashes with internal macro in Windows system header

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97362

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |WAITING

--- Comment #7 from Jonathan Wakely <redi at gcc dot gnu.org> ---
ping

[Bug libstdc++/97362] [8/9/10 Regression] `__deref` in <functional> in debug mode clashes with internal macro in Windows system header

[frankhb1989 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97362

--- Comment #8 from frankhb1989 at gmail dot com ---
The first diagnostic message of `#pragma GCC poison __deref` points to <sal.h>
in my MSYS2 installation.

The change is made here:
https://sourceforge.net/p/mingw-w64/mingw-w64/ci/555bee806560144c6a59077f3c860bc83411153c/.

[Bug libstdc++/97362] [8/9/10 Regression] `__deref` in <functional> in debug mode clashes with internal macro in Windows system header

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97362

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |ASSIGNED

--- Comment #9 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Ah, it's a recent change. I think my mingw headers are too old.

I guess I'd better backport this then.

[Bug libstdc++/97362] [8/9/10 Regression] `__deref` in <functional> in debug mode clashes with internal macro in Windows system header

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97362

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|                            |10.3.0

--- Comment #10 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #5)
> Fixed on trunk with g:2137aa92412da363d52ef699987441be28b239d0 which for
> some reason didn't get added here.

And g:e9c2c61b9157e15311dbf0a73c575ae0eae79cb3 on the gcc-10 branch.

[Bug libstdc++/97362] [8/9 Regression] `__deref` in <functional> in debug mode clashes with internal macro in Windows system header

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97362

--- Comment #11 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:

https://gcc.gnu.org/g:18e4119b23175e2de2fecdaae052c5a8729d9f56

commit r9-9361-g18e4119b23175e2de2fecdaae052c5a8729d9f56
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Sat Oct 10 21:22:12 2020 +0100

    libstdc++: Replace use of reserved name that clashes [PR 97362]

    The name __deref is defined as a macro by Windows headers.

    This renames the __deref() helper function to __ref. It doesn't actually
    dereference an iterator. it just has the same type as the iterator's
    reference type.

    libstdc++-v3/ChangeLog:

            PR libstdc++/97362
            * doc/html/manual/source_code_style.html: Regenerate.
            * doc/xml/manual/appendix_contributing.xml: Add __deref to
            BADNAMES.
            * include/debug/functions.h (_Irreflexive_checker::__deref):
            Rename to __ref.

    (cherry picked from commit 2137aa92412da363d52ef699987441be28b239d0)

[Bug libstdc++/97362] [8/9 Regression] `__deref` in <functional> in debug mode clashes with internal macro in Windows system header

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97362

--- Comment #12 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-8 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:

https://gcc.gnu.org/g:661dacec8fb149582a2508494ed927ee3387c7f0

commit r8-10851-g661dacec8fb149582a2508494ed927ee3387c7f0
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Sat Oct 10 21:22:12 2020 +0100

    libstdc++: Replace use of reserved name that clashes [PR 97362]

    The name __deref is defined as a macro by Windows headers.

    This renames the __deref() helper function to __ref. It doesn't actually
    dereference an iterator. it just has the same type as the iterator's
    reference type.

    libstdc++-v3/ChangeLog:

            PR libstdc++/97362
            * doc/html/manual/source_code_style.html: Regenerate.
            * doc/xml/manual/appendix_contributing.xml: Add __deref to
            BADNAMES.
            * include/debug/functions.h (_Irreflexive_checker::__deref):
            Rename to __ref.

    (cherry picked from commit 2137aa92412da363d52ef699987441be28b239d0)

[Bug libstdc++/97362] [8/9 Regression] `__deref` in <functional> in debug mode clashes with internal macro in Windows system header

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97362

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #13 from Jonathan Wakely <redi at gcc dot gnu.org> ---
.