Compilation/intellisense: dotnet9 much slower than netstandard2.0 (with timings)

[charlesroddie]

Timings:

The projects explicitly type all type arguments and all inputs but not all outputs (which could be added if it helps compilation time) and generally don't do anything fancy. They do use some overloaded methods which can be removed if it helps performance, and some op_Implicits (which are too convenient to remove).

Related issue: #17501

Some work being done in #18190

[vzarytovskii]

This is caused by #17501, fix is disabled for tooling because of the lack of proper caching solution in compiler.

[T-Gro]

Hi @charlesroddie , could you please attach a code sample of where this happens as well, to get a real-life test captured as part of a solution?

This is also to confirm the standing hypothesis of this being caused by big interface hierarchies, such as those added by INumber and other interfaces with static abstracts (which are not existing in ns2.0)

[charlesroddie]

@T-Gro is it possible to get the information from an existing codebase. Right now I can try any instructions or given access if needed.

If a separate reproduction is needed I can try to do that in a few weeks but will take longer and would probably involve codegenning different types of F# code until unexpectedly long compilation time is found.

[T-Gro]

Anything that can be used while measuring solution(s) against it. If it is proprietary, then one-time access for evaluation would also good. Anything shareable which could stay in this repo as a test against regressions would be even better.