Unexpected error in system/lib/libcxx/include/__format/format_arg_store.h

[SaraBaradaran]

I faced the following error when compiling network_opt (https://github.com/google/network-opt) using Emscripten. It seems there is a bug in LLVM's libc++ header system/lib/libcxx/include/__format/format_arg_store.h.

version: 3.1.54

/home/sara/emsdk/upstream/emscripten/cache/sysroot/include/c++/v1/__format/format_arg_store.h:227:34: error: parameter declarator cannot be qualified
  227 | template <class _Context, size_t N>
      |                                  ^

You can reproduce the error using the following commands:

$ git clone https://github.com/google/network-opt
$ cd network-opt
$ mkdir build
$ cd build
$ emcmake cmake -DCMAKE_CXX_FLAGS="-sUSE_BOOST_HEADERS" ..
$ emmake cmake --build .

[kripken]

I tried with 3.1.64. I had to add

git submodule init
git submodule update

to those commands. After that, it errors for me on

[ 39%] Building CXX object external/abseil-cpp/absl/hash/CMakeFiles/absl_hash.dir/internal/hash.cc.o
In file included from network-opt/external/abseil-cpp/absl/hash/internal/hash.cc:15:
In file included from network-opt/external/abseil-cpp/absl/hash/internal/hash.h:48:
In file included from network-opt/external/abseil-cpp/absl/container/fixed_array.h:50:
network-opt/external/abseil-cpp/absl/container/internal/compressed_tuple.h:252:42: error: no member named 'get' in the global namespace
  252 |     return std::move(*this).StorageT<I>::get();
      |                                        ~~^
network-opt/external/abseil-cpp/absl/container/internal/compressed_tuple.h:257:43: error: no member named 'get' in the global namespace
  257 |     return absl::move(*this).StorageT<I>::get();
      |                                         ~~^
2 errors generated.

which I do not understand, but looks like a project-specific issue?

[SaraBaradaran]

I tried with 3.1.64. I had to add

git submodule init
git submodule update

to those commands. After that, it errors for me on

[ 39%] Building CXX object external/abseil-cpp/absl/hash/CMakeFiles/absl_hash.dir/internal/hash.cc.o
In file included from network-opt/external/abseil-cpp/absl/hash/internal/hash.cc:15:
In file included from network-opt/external/abseil-cpp/absl/hash/internal/hash.h:48:
In file included from network-opt/external/abseil-cpp/absl/container/fixed_array.h:50:
network-opt/external/abseil-cpp/absl/container/internal/compressed_tuple.h:252:42: error: no member named 'get' in the global namespace
  252 |     return std::move(*this).StorageT<I>::get();
      |                                        ~~^
network-opt/external/abseil-cpp/absl/container/internal/compressed_tuple.h:257:43: error: no member named 'get' in the global namespace
  257 |     return absl::move(*this).StorageT<I>::get();
      |                                         ~~^
2 errors generated.

which I do not understand, but looks like a project-specific issue?

Thank you for replying. I found there is no version 3.1.64 in emsdk. The latest version is 3.1.63. When I tried with 3.1.54, I received the following error message. I've also added git submodule init and git submodule update as you mentioned.

[ 68%] Building CXX object CMakeFiles/network_opt.dir/src/network_opt_local.cc.o
In file included from /home/sara/test2/network-opt/src/network_opt_local.cc:16:
In file included from /home/sara/emsdk/upstream/emscripten/cache/sysroot/include/c++/v1/chrono:796:
In file included from /home/sara/emsdk/upstream/emscripten/cache/sysroot/include/c++/v1/__chrono/formatter.h:23:
In file included from /home/sara/emsdk/upstream/emscripten/cache/sysroot/include/c++/v1/__chrono/ostream.h:30:
In file included from /home/sara/emsdk/upstream/emscripten/cache/sysroot/include/c++/v1/__format/format_functions.h:19:
/home/sara/emsdk/upstream/emscripten/cache/sysroot/include/c++/v1/__format/format_arg_store.h:227:34: error: parameter declarator cannot be qualified
  227 | template <class _Context, size_t N>
      |                                  ^
/home/sara/test2/network-opt/src/network_opt.h:29:30: note: expanded from macro 'N'
   29 | #define N network_opt::Node::create
      |           ~~~~~~~~~~~~~~~~~~~^
In file included from /home/sara/test2/network-opt/src/network_opt_local.cc:16:
In file included from /home/sara/emsdk/upstream/emscripten/cache/sysroot/include/c++/v1/chrono:796:
In file included from /home/sara/emsdk/upstream/emscripten/cache/sysroot/include/c++/v1/__chrono/formatter.h:23:
In file included from /home/sara/emsdk/upstream/emscripten/cache/sysroot/include/c++/v1/__chrono/ostream.h:30:
In file included from /home/sara/emsdk/upstream/emscripten/cache/sysroot/include/c++/v1/__format/format_functions.h:19:
/home/sara/emsdk/upstream/emscripten/cache/sysroot/include/c++/v1/__format/format_arg_store.h:229:48: error: reference to overloaded function could not be resolved; did you mean to call it with no arguments?
  229 |   __basic_format_arg_value<_Context> __values_[N];
      |                                                ^

When I tried with Emscripten version 3.1.63, there wasn't such an error. This issue seems to be solved by LLVM's libc++ headers 18 as did by (#21638)