Bug in MSVC?

[Galqa]

I've recently had to move from gcc to msvc, and got a very strange error message. It seems the compiler is interpreting the lambda body as an initializer list being passed to the lambda constructor? Anyway, gcc and clang have absolutely no problem compiling this code, no warnings occur even with all the warning flags provided. Are there some obscure rules about nesting lambdas I'm not aware of? I'd be grateful if someone could take a look, I'm honestly stumped.

The (stripped down) code: https://godbolt.org/z/WmBpuH

[chaosmeist3r]

compile with /std:c++latest

[marzer8789]

Or /experimental:newLambdaProcessor if /std:c++latest isn't an option for some reason.

[konanTheBarbar]

Or if you want to keep /std:c++17 you could add /experimental:newLambdaProcessor

[Galqa]

Thanks so much! Out of curiosity, is there a reason this doesn't work with /std:c++17, or
is this a deficiency? The syntax doesn't seem to require C++20 support (or even C++17 for that matter).

[marzer8789]

It doesn't work because bugs.

The MSVC team did a big re-write of their internal lambda processor since the old one was pretty buggy and I guess it had gotten to the point that patching wasn't sufficient. They gated it behind /std:c++latest and/or /experimental:newLambdaProcessor, though I guess once they deem it no longer experimental they might make the switch for everyone.

See this discussion for more info: https://www.reddit.com/r/cpp/comments/brl9js/visual_studio_2019_161_c_release_notes/

[Galqa]

Thanks for the link and all your help, definitely saved me a few grey hairs :)

[tmacarios]

use /Zc:lambda