Compilation error with Nintendo 3DS homebrew compiler

[glebm]

I tried updating fmt to v10.1.1 in DevilutionX (diasurgical/devilutionX#6585) and got an error on one of the oddball platforms.

The platform is Nintendo 3DS homebrew, it uses a GCC 13.2.0-based compiler, and the error is this:

In file included from /root/repo/Source/utils/log.hpp:6,
                 from /root/repo/Source/platform/ctr/sockets.cpp:8:
/root/repo/build/_deps/libfmt-src/include/fmt/core.h:1557:68: error: template argument 1 is invalid
 1557 | template <bool PACKED, typename Context, typename T, FMT_ENABLE_IF(PACKED)>
      |                                                                    ^~~~~~
/root/repo/build/_deps/libfmt-src/include/fmt/core.h:286:48: note: in definition of macro 'FMT_ENABLE_IF'
  286 | #  define FMT_ENABLE_IF(...) fmt::enable_if_t<(__VA_ARGS__), int> = 0
      |                                                ^~~~~~~~~~~
/root/repo/build/_deps/libfmt-src/include/fmt/core.h:286:59: error: expected identifier before ')' token
  286 | #  define FMT_ENABLE_IF(...) fmt::enable_if_t<(__VA_ARGS__), int> = 0
      |                                                           ^
/root/repo/build/_deps/libfmt-src/include/fmt/core.h:1557:54: note: in expansion of macro 'FMT_ENABLE_IF'
 1557 | template <bool PACKED, typename Context, typename T, FMT_ENABLE_IF(PACKED)>
      |                                                      ^~~~~~~~~~~~~
/root/repo/build/_deps/libfmt-src/include/fmt/core.h:286:59: error: expected '>' before ')' token
  286 | #  define FMT_ENABLE_IF(...) fmt::enable_if_t<(__VA_ARGS__), int> = 0
      |                                                           ^
/root/repo/build/_deps/libfmt-src/include/fmt/core.h:1557:54: note: in expansion of macro 'FMT_ENABLE_IF'
 1557 | template <bool PACKED, typename Context, typename T, FMT_ENABLE_IF(PACKED)>
      |                                                      ^~~~~~~~~~~~~
/root/repo/build/_deps/libfmt-src/include/fmt/core.h:286:59: error: expected unqualified-id before ')' token
  286 | #  define FMT_ENABLE_IF(...) fmt::enable_if_t<(__VA_ARGS__), int> = 0
      |                                                           ^
/root/repo/build/_deps/libfmt-src/include/fmt/core.h:1557:54: note: in expansion of macro 'FMT_ENABLE_IF'
 1557 | template <bool PACKED, typename Context, typename T, FMT_ENABLE_IF(PACKED)>
      |                                                      ^~~~~~~~~~~~~

Failing build: https://app.circleci.com/pipelines/github/diasurgical/devilutionX/18895/workflows/2775b1cd-f0ad-4945-911c-530cfc7aca1d/jobs/116663

I cannot reproduce this error on godbolt. I also don't really understand the error message, the code seems fine to me.
I'd appreciate any thoughts on what this could be.

[glebm]

I wonder if this is because of the following macro in 3ds/types.h:

https://github.com/devkitPro/libctru/blob/a4634c02905a824d01feae338d1c472ab5dae1eb/libctru/include/3ds/types.h#L51-L52

[glebm]

Yep that's it!
Godbolt: https://godbolt.org/z/1GWe1oGa7

I've filed an issue with the 3DS SDK devkitPro/libctru#530 and also sent a workaround here

[TuxSH]

I think there are two different issues here:

• an external lib using non-namespaced macros
• this library using a full-uppercase identifier name on something that is neither a macro nor a plain enum (bool PACKED template parameter)

[glebm]

Yes, this issue only tracks (2). I filed an issue for (1) with the external lib (devkitPro/libctru#530).

[vitaut]

Commented on the PR.