test MSVC default conformance mode, using its legacy lambda processor

[N-Dekker]

The added "test_release_x64_legacy_lambda.vcxproj" is basically just a copy of "test_release_x64.vcxproj", but it has an extra property ConformanceMode, set to Default. Which triggers MSVC to use its "legacy lambda processor".

With such a configuration, the user may need to define TOML_DISABLE_CONDITIONAL_NOEXCEPT_LAMBDA.

Update, March 4, 2025: The pull request now also adds /permissive builds to the CI, using TOML_DISABLE_CONDITIONAL_NOEXCEPT_LAMBDA to prevent compile errors.

Follow-up to commit cbc00d6 "add TOML_DISABLE_CONDITIONAL_NOEXCEPT_LAMBDA workaround MSVC error C2057 (#247)"

• I've read CONTRIBUTING.md
• I've rebased my changes against the current HEAD of origin/master (if necessary)
• I've added new test cases to verify my change
• I've regenerated toml.hpp (how-to)
• I've updated any affected documentation
• I've rebuilt and run the tests with at least one of:
  • Clang 8 or higher
  • GCC 8 or higher
  • MSVC 19.20 (Visual Studio 2019) or higher
• I've added my name to the list of contributors in README.md

[N-Dekker]

@marzer Does the CI build your Visual Studio Solution file, "toml++.sln"?

[marzer]

Nope. That's just something I use when I work on it locally.

Though, these days I don't use VS as much and am starting to prefer a non VS-oriented workflow, so I wouldn't worry about it tbh.

The windows runner uses meson, just like the Linux ones. I guess you'd need to add a new test exe with different options in for the windows run.

[N-Dekker]

@marzer I think this pull request is ready now, as it tests both /permissive (including the old lambda processor) and /permissive- (non-permissive, including the new lambda processor) at the CI:

Non-permissive conformance mode:

• ci / windows (debug, false)
• ci / windows (release, false)

Permissive conformance mode + TOML_DISABLE_CONDITIONAL_NOEXCEPT_LAMBDA:

• ci / windows (debug, true)
• ci / windows (release, true)

Minor issue: somehow, adding /permissive triggers some compiler warnings at the CI for windows (debug, true) and (release, true), saying:

cl : Command line warning D9025 : overriding '/permissive-' with '/permissive'

Does that bother you? I think these warnings can be ignored safely. If you want to have them fixed anyway, do you have a suggestion how?

[marzer]

Sorry, missed that you'd updated this.

Warning about the CLI argument is fine, no problem. Happy to merge this one as-is. Thanks! 🎉

[N-Dekker]

@marzer Thanks again for merging, Mark! I hope you can still consider adding a new tag to the master branch. For our project (elastix), we prefer to use tagged versions of third party libraries. And it has been a while already, the last toml++ tag appears 30 commits and 17 months ago: https://github.com/marzer/tomlplusplus/tags

[marzer]

Yeah, I do intend to make a new release soon, no worries. Will try to do it in the next week or so.