USE_SYSTEM_FMTLIB seems to be non functional

[autoantwort]

Describe the bug
I have specified USE_SYSTEM_FMTLIB but it looks like fmtlib is built anyway.
I get the following error:

[43/230] /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++  -I/Users/leanderSchulten/git_projekte/vcpkg/buildtrees/wpilib/src/868759e556-81ce2d8562.clean/wpiutil/src/main/native/include -I/Users/leanderSchulten/git_projekte/vcpkg/buildtrees/wpilib/src/868759e556-81ce2d8562.clean/wpiutil/src/main/native/thirdparty/memory/include -I/Users/leanderSchulten/git_projekte/vcpkg/buildtrees/wpilib/src/868759e556-81ce2d8562.clean/wpiutil/src/main/native/thirdparty/json/include -I/Users/leanderSchulten/git_projekte/vcpkg/buildtrees/wpilib/src/868759e556-81ce2d8562.clean/wpiutil/src/main/native/thirdparty/llvm/include -I/Users/leanderSchulten/git_projekte/vcpkg/buildtrees/wpilib/src/868759e556-81ce2d8562.clean/wpiutil/src/main/native/thirdparty/mpack/include -I/Users/leanderSchulten/git_projekte/vcpkg/buildtrees/wpilib/src/868759e556-81ce2d8562.clean/wpiutil/src/main/native/thirdparty/sigslot/include -isystem /Users/leanderSchulten/git_projekte/vcpkg/vcpkg_installed/arm64-osx/include -fPIC -g -arch arm64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX13.3.sdk -Wall -pedantic -Wextra -Werror -Wno-unused-parameter -Wno-deprecated-anon-enum-enum-conversion -std=gnu++20 -MD -MT wpiutil/CMakeFiles/wpiutil.dir/src/main/native/thirdparty/fmtlib/src/format.cpp.o -MF wpiutil/CMakeFiles/wpiutil.dir/src/main/native/thirdparty/fmtlib/src/format.cpp.o.d -o wpiutil/CMakeFiles/wpiutil.dir/src/main/native/thirdparty/fmtlib/src/format.cpp.o -c /Users/leanderSchulten/git_projekte/vcpkg/buildtrees/wpilib/src/868759e556-81ce2d8562.clean/wpiutil/src/main/native/thirdparty/fmtlib/src/format.cpp
FAILED: wpiutil/CMakeFiles/wpiutil.dir/src/main/native/thirdparty/fmtlib/src/format.cpp.o 
/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/c++  -I/Users/leanderSchulten/git_projekte/vcpkg/buildtrees/wpilib/src/868759e556-81ce2d8562.clean/wpiutil/src/main/native/include -I/Users/leanderSchulten/git_projekte/vcpkg/buildtrees/wpilib/src/868759e556-81ce2d8562.clean/wpiutil/src/main/native/thirdparty/memory/include -I/Users/leanderSchulten/git_projekte/vcpkg/buildtrees/wpilib/src/868759e556-81ce2d8562.clean/wpiutil/src/main/native/thirdparty/json/include -I/Users/leanderSchulten/git_projekte/vcpkg/buildtrees/wpilib/src/868759e556-81ce2d8562.clean/wpiutil/src/main/native/thirdparty/llvm/include -I/Users/leanderSchulten/git_projekte/vcpkg/buildtrees/wpilib/src/868759e556-81ce2d8562.clean/wpiutil/src/main/native/thirdparty/mpack/include -I/Users/leanderSchulten/git_projekte/vcpkg/buildtrees/wpilib/src/868759e556-81ce2d8562.clean/wpiutil/src/main/native/thirdparty/sigslot/include -isystem /Users/leanderSchulten/git_projekte/vcpkg/vcpkg_installed/arm64-osx/include -fPIC -g -arch arm64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX13.3.sdk -Wall -pedantic -Wextra -Werror -Wno-unused-parameter -Wno-deprecated-anon-enum-enum-conversion -std=gnu++20 -MD -MT wpiutil/CMakeFiles/wpiutil.dir/src/main/native/thirdparty/fmtlib/src/format.cpp.o -MF wpiutil/CMakeFiles/wpiutil.dir/src/main/native/thirdparty/fmtlib/src/format.cpp.o.d -o wpiutil/CMakeFiles/wpiutil.dir/src/main/native/thirdparty/fmtlib/src/format.cpp.o -c /Users/leanderSchulten/git_projekte/vcpkg/buildtrees/wpilib/src/868759e556-81ce2d8562.clean/wpiutil/src/main/native/thirdparty/fmtlib/src/format.cpp
/Users/leanderSchulten/git_projekte/vcpkg/buildtrees/wpilib/src/868759e556-81ce2d8562.clean/wpiutil/src/main/native/thirdparty/fmtlib/src/format.cpp:35:75: error: expected '(' for function-style cast or type construction
                                 basic_format_args<FMT_BUFFER_CONTEXT(char)>,
                                                                      ~~~~^
/Users/leanderSchulten/git_projekte/vcpkg/buildtrees/wpilib/src/868759e556-81ce2d8562.clean/wpiutil/src/main/native/thirdparty/fmtlib/src/format.cpp:34:23: error: explicit instantiation of 'vformat_to' does not refer to a function template, variable template, member function, member class, or static data member
template FMT_API void vformat_to(buffer<char>&, string_view,
                      ^
/Users/leanderSchulten/git_projekte/vcpkg/vcpkg_installed/arm64-osx/include/fmt/format.h:4554:6: note: candidate template ignored: failed template argument deduction
void vformat_to(buffer<Char>& buf, basic_string_view<Char> fmt,
     ^
2 errors generated.

To Reproduce
Steps to reproduce the behavior:
Specify -DUSE_SYSTEM_FMTLIB=ON and have fmtlib 10.0.0 installed.

Expected behavior
Do not build fmtlib and use the provided one.

Additional context
Happens with the code from the main branch. Used code: microsoft/vcpkg#32461

[calcmogul]

It worked for Arch Linux packages as of 2023.4.3: https://aur.archlinux.org/packages/wpimath

[calcmogul]

Looks like the wpiutil add_library() call still lists the local fmtlib files.

[autoantwort]

Yes that is what I also discovered. I have created #5429