[Bug c++/97484] New: typedef conflict for "byte" in GCC11 for MinGW-w64

[Bug c++/97484] New: typedef conflict for "byte" in GCC11 for MinGW-w64

[brechtsanders at users dot sourceforge.net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97484

            Bug ID: 97484
           Summary: typedef conflict for "byte" in GCC11 for MinGW-w64
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: brechtsanders at users dot sourceforge.net
  Target Milestone: ---

I just built GCC11 snapshot 20201011 for the MinGW-w64 platform and noticed
that some things won't build with it because "byte" now has conflicting
definitions.
Windows seems to already define this in rpcndr.h, which is included from
windows.h.
But it's also defined in C++' cpp_type_traits.

The errors below are from an attempt to compile Ninja with GCC11 snapshot
20201011.

These issues were not present with GCC 11 or lower.

In file included from
d:\prog\winlibs32_stage\mingw32\i686-w64-mingw32\include\wtypes.h:8,
                 from
d:\prog\winlibs32_stage\mingw32\i686-w64-mingw32\include\winscard.h:10,
                 from
d:\prog\winlibs32_stage\mingw32\i686-w64-mingw32\include\windows.h:97,
                 from .\src\disk_interface.cc:27:
d:\prog\winlibs32_stage\mingw32\i686-w64-mingw32\include\rpcndr.h:64:11: error:
reference to 'byte' is ambiguous
   64 |   typedef byte cs_byte;
      |           ^~~~
In file included from
d:\prog\winlibs32_stage\mingw32\include\c++\11.0.0\bits\stl_algobase.h:61,
                 from
d:\prog\winlibs32_stage\mingw32\include\c++\11.0.0\bits\stl_tree.h:63,
                 from
d:\prog\winlibs32_stage\mingw32\include\c++\11.0.0\map:60,
                 from .\src\disk_interface.h:18,
                 from .\src\disk_interface.cc:15:
d:\prog\winlibs32_stage\mingw32\include\c++\11.0.0\bits\cpp_type_traits.h:404:30:
note: candidates are: 'enum class std::byte'
  404 |   enum class byte : unsigned char;
      |                              ^~~~
In file included from
d:\prog\winlibs32_stage\mingw32\i686-w64-mingw32\include\wtypes.h:8,
                 from
d:\prog\winlibs32_stage\mingw32\i686-w64-mingw32\include\winscard.h:10,
                 from
d:\prog\winlibs32_stage\mingw32\i686-w64-mingw32\include\windows.h:97,
                 from .\src\disk_interface.cc:27:
d:\prog\winlibs32_stage\mingw32\i686-w64-mingw32\include\rpcndr.h:63:25: note: 
               'typedef unsigned char byte'
   63 |   typedef unsigned char byte;
      |                         ^~~~

[Bug libstdc++/97484] typedef conflict for "byte" in GCC11 for MinGW-w64

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97484

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c++                         |libstdc++
             Target|                            |x86_64-MinGW-W64

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
I guess there needs to be a workaround on the windows side?

[Bug libstdc++/97484] typedef conflict for "byte" in GCC11 for MinGW-w64

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97484

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Does Ninja use
using namespace std;
before including standard headers, or does some mingw header use that?

[Bug libstdc++/97484] typedef conflict for "byte" in GCC11 for MinGW-w64

[brechtsanders at users dot sourceforge.net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97484

--- Comment #3 from Brecht Sanders <brechtsanders at users dot sourceforge.net> ---
MinGW is pure C, so it doesn't use: using namespace std;
But I do see Ninja doing this before including windows.h.
However GCC 10 and older have no issue with this.
What changed in GCC 11 to cause the issue?

[Bug libstdc++/97484] typedef conflict for "byte" in GCC11 for MinGW-w64

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97484

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
(In reply to Brecht Sanders from comment #3)
> MinGW is pure C, so it doesn't use: using namespace std;
> But I do see Ninja doing this before including windows.h.

Then it is Ninja that needs to be fixed.  One can use using namespace std;,
but better only after including all headers one has no control over, because it
significantly affects name lookup.

> However GCC 10 and older have no issue with this.
> What changed in GCC 11 to cause the issue?

GCC 11 defaults to -std=c++17, while GCC 10 defaulted to -std=c++14.
I bet it won't compile even with GCC 10 if you use -std=c++17.

[Bug libstdc++/97484] typedef conflict for "byte" in GCC11 for MinGW-w64

[brechtsanders at users dot sourceforge.net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97484

Brecht Sanders <brechtsanders at users dot sourceforge.net> changed:

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

--- Comment #5 from Brecht Sanders <brechtsanders at users dot sourceforge.net> ---
Yes, you're right, when setting CXXFLAGS="-std=c++17" and building with GCC 10
Ninja also fails to build.

I have opened a ticket with Ninja for this, see:
https://github.com/ninja-build/ninja/issues/1861

[Bug libstdc++/97484] typedef conflict for "byte" in GCC11 for MinGW-w64

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97484

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|FIXED                       |INVALID

[Bug libstdc++/97484] typedef conflict for "byte" in GCC11 for MinGW-w64

[Abderraouf.bousri at g dot enp.edu.dz]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97484

Abderraouf Bousri <Abderraouf.bousri at g dot enp.edu.dz> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |Abderraouf.bousri at g dot enp.edu
                   |                            |.dz

--- Comment #6 from Abderraouf Bousri <Abderraouf.bousri at g dot enp.edu.dz> ---
yes you are right, it was generating that error when i tried to compile with
those configurations :

CMAKE_CXX_STANDARD 17   and g++ (8.0, 9.0, 10.0 and 12), also i tried with
visual studio and Ninja.

i changed the flag to c++14, now it works (with g++ 8.0) :
    set(CMAKE_CXX_STANDARD 14)  #in your CMakeLists.txt
run this cmake command on windows : 
    cmake -G "MinGW Makefiles" -D CMAKE_CXX_COMPILER=g++ ..