unicode4 test consistently fails on RISC-V hardware

[Madouura]

Description

When compiling nlohmann_json on NixOS, on a RISC-V 64 bit system, StarFive VisionFive, the unicode4 test times out and fails the build.
This does not happen on regular x86_64 systems, so I believe a fix may be needed for either the test, or the thing being tested, regarding RISC-V compatibility.

Reproduction steps

Attempt to build nlohmann_json on a RISC-V system, either hardware or through a virtual machine like QEMU, on NixOS.
If you happen to have a StarFive VisionFive board, I suggest using this PR to reproduce: NixOS/nixpkgs#168826

Expected vs. actual results

unicode4 test should not be timing out.

Minimal code example

No response

Error messages

https://gist.github.com/Madouura/edf2ac1b06bf6e63507b9dc9bb338064

Compiler and operating system

GCC11 IIRC, NixOS

Library version

3.10.5

Validation

• The bug also occurs if the latest version from the develop branch is used.
• I can successfully compile and run the unit tests.

[falbrechtskirchinger]

Increase the timeout then? This happens in CI sometimes as well.

[Madouura]

I am very unfamiliar with this project, would you mind pointing to me where I can do that?
Is it a cmake option or something in the unit test itself?

[falbrechtskirchinger]

See ctest --help.

--timeout = Set the default test timeout.

The default is 1500 seconds.

[falbrechtskirchinger]

I'll look into raising the timeout for test-unicode4_cpp11 permanently.

[falbrechtskirchinger]

https://github.com/NixOS/nixpkgs/blob/c199a0a796c748509019139e850485a90f4d3f60/pkgs/development/libraries/nlohmann_json/default.nix#L26-L29

Have you considered building with the CMake option JSON_FastTests=ON?

  cmakeFlags = [
    "-DBuildTests=${if doCheck then "ON" else "OFF"}"
    "-DJSON_FastTests=ON"
    "-DJSON_MultipleHeaders=ON"
  ] ++ lib.optional doCheck "-DJSON_TestDataDirectory=${testData}";

Also, BuildTests is wrong. The option is named JSON_BuildTests. As is doCheck doesn't affect unit testing.

[Madouura]

I'll test it out and report back when done, thank you.

  cmakeFlags = [
    "-DJSON_BuildTests=${if doCheck then "ON" else "OFF"}"
    "-DJSON_FastTests=ON"
    "-DJSON_MultipleHeaders=ON"
  ] ++ lib.optional doCheck "-DJSON_TestDataDirectory=${testData}";

[Madouura]

Successful build in my case, with FastTests.
Should I keep this issue open, since you have a PR ready?

[falbrechtskirchinger]

Good to hear!
You can leave the issue open. I've linked it to the PR and it should be closed on merge.