C++20 MSVC Syntax Error [CMake] about tomlplusplus

Ah well, thank you for the quick replies. I'll be closing it now, thanks for the great library and I apologise for the inconveniences 🤗

Also, no modifications were made to the header. I tried both the "Single Header Flavor" and "Regular Flavour". They both threw this error.

^ However the Regular Flavour had errors on the array and parser files. If you would like the error messages let me know.

[marzer]

Hmm, weird. MSVC is the environment I use to develop toml++ so it's weird that I didn't see this. I'll do some investigating. Two things I need from you:

1. Tell me the value of _MSC_FULL_VER from your compiler (or build with /Bv and tell me the version it spams you with at compile-time)
2. Open the toml++ visual studio solution (tomlplusplus/vs/toml++.sln) and try building any of the example projects, and tell me what happens.

Hmm, weird. MSVC is the environment I use to develop toml++ so it's weird that I didn't see this. I'll do some investigating. Two things I need from you:

1. Tell me the value of _MSC_FULL_VER from your compiler (or build with /Bv and tell me the version it spams you with at compile-time)
2. Open the toml++ visual studio solution (tomlplusplus/vs/toml++.sln) and try building any of the example projects, and tell me what happens.

Thank you for the quick reply,

The value: _MSC_FULL_VER: 192628806

And for the Visual Studio solution, even though my CLion project is using the same compiler, compiled successfully!

I find this really strange.

This shouldn't be an issue as I have my includes setup correctly:
include_directories(include/)

My CMakeLists.txt:

Using the Visual Studio Compiler:

I will load the CMake project into visual studio and see if it compiles correctly on there.

EDIT:

The error occurs on Visual Studio with CMake too

Potentially an incompatability issue with CMake..? I'll attach my CMakeLists.txt in a second.

[marzer]

Hmm, yeah. It seems like a CMake-related issue. Are you able to see the full command line that gets sent to MSVC anywhere? If so, post that. My suspicion is that MSVC isn't being invoked with the right C++ standard level.

Command line: "cmd.exe" /c ""c:\program files (x86)\microsoft visual studio\2019\community\common7\ide\commonextensions\microsoft\cmake\CMake\bin\cmake.exe" -G "Ninja" -DCMAKE_INSTALL_PREFIX:PATH="C:\Users\root\Documents\GitHub\ezpkg\out\install\x64-Release" -DCMAKE_C_COMPILER:FILEPATH="C:/Program Files (x86)/Microsoft Visual Studio/2019/Community/VC/Tools/MSVC/14.26.28801/bin/HostX64/x64/cl.exe" -DCMAKE_CXX_COMPILER:FILEPATH="C:/Program Files (x86)/Microsoft Visual Studio/2019/Community/VC/Tools/MSVC/14.26.28801/bin/HostX64/x64/cl.exe" -DCMAKE_TOOLCHAIN_FILE="C:/Users/root/Desktop/vcpkg/scripts/buildsystems/vcpkg.cmake" -DCMAKE_BUILD_TYPE="Release" -DCMAKE_MAKE_PROGRAM="c:\program files (x86)\microsoft visual studio\2019\community\common7\ide\commonextensions\microsoft\cmake\Ninja\ninja.exe" "C:\Users\root\Documents\GitHub\ezpkg" 2>&1"

EDIT: Above is cmake invocation ^ not msvc sorry lol

Is that of Visual Studio, can't seem to find the CLion command, they are throwing the same error so I suppose the difference isn't the IDEs fault anyway.

[marzer]

Nah, that looks like the invocation of cmake. I'm looking for the invocation of cl.exe (msvc), and the arguments passed to that. My suspicion is that it's being invoked as C++14, which is the default if no standard level argument is given. For C++17 it's /std:c++17, and for C++20 it's /std:c++latest (there's no /std:c++20 flag yet since their implementation isn't currently complete).

The reason I'm thinking this is that those syntax errors look a lot like the ones you get when MSVC doesn't understand C++17's nested-namespace definitions in C++14 mode.

(https://docs.microsoft.com/en-us/cpp/build/reference/std-specify-language-standard-version?view=vs-2019)

[marzer]

Alternatively you could try lowering CMAKE_CXX_STANDARD to 17 (since I assume that will work correctly for MSVC), just to see if you get a different result.

A quick stackoverflow and.

😓

[marzer]

Hah, classic CMake.

Oh gosh, this is embarrassing, I sort of jumped to a conclusion and this does appear to be a different issue. If you build on a lower standard (e.g 11/14), then it throws this
error.

When changing it to C++17, it throws said errors.

Very sorry, for closing it prematurely, I thought I had found a solution.

TL:DR I didn't test my solution before closing the issue, the problem persists. Apologies.

[marzer]

Ah well.

You said you're using exceptions (/EHsc), but those messages indicate otherwise (the warning in <vector>, and toml++ is using the internal noex ABI namespace). If you are meant to be using exceptions, try setting TOML_EXCEPTIONS to 1 before including toml.hpp, e.g.:

#define TOML_EXCEPTIONS 1
#include <toml++/toml.hpp>

I have fixed the exceptions not being enabled issue, and defined TOML_EXCEPTIONS 1. The issue persists.

[marzer]

Ohhhhh. It's std::numeric_limits::max() getting nuked by a max macro. I'll fix it library-side, give me a few minutes.

I'll let you know the results once it's been pushed 😀👍

[marzer]

You can test it locally; change toml.hpp line 1426 8103 to this:

if (result > static_cast<uint64_t>((std::numeric_limits<int64_t>::max)()) + (sign < 0 ? 1ull : 0ull))

(I added an extra set of parens around std::numeric_limits<int64_t>::max)

Er? (I'm on the latest single header.)

[marzer]

Oh, wow. Where the fuck did I get 1426 from?? Line 8103 was the one, lol.

Doesn't matter now, I've pushed the fix.

Yeah, I found it myself and fixed it just as I saw your new comment 🤣 Everything works all good now 👍 Thanks!

[marzer]

:D Hooray!

[marzer]

Side note: If you changed your compiler settings to enable exceptions properly, you shouldn't need to explicitly set TOML_EXCEPTIONS yourself, since the default behavior is to match whatever your compiler is set to. I only suggested that as a brute-force. It won't do you any harm to leave it set explicitly, though. That option is always going to be there.

Okay thanks! I have exceptions enabled properly now so I'll remove it.