[clang] [C++20] [Modules] [Driver] Don't enable -fdelayed-template-parsing by default on windows with C++20 modules (PR #69431)

[Chuanqi Xu via cfe-commits]

ChuanqiXu9 wrote:

> > > I still support disabling delayed template parsing by default in all configurations. Ultimately, this feature is a source of bugs, and we should start the clock on its deprecation and removal. This, of course, involves real work, and I haven't allocated any time (mine or others') to it.
> > 
> > 
> > So @ChuanqiXu9 's patch is at least a conservative step towards that (limiting the change to C++20 modules where we know there is a problem) - we could then extend that to C++20, in general (as per @zero9178 's comment above). As you say deprecation and removal is more work.
> 
> Yeah, how about we at least match MSVC here - and. generalize it to C++20 today, leaving the older deprecation work to others/another time?

+1 and done in the latest commit!

https://github.com/llvm/llvm-project/pull/69431