[PATCH] D144084: [LLD] [COFF] Don't try to detect MSVC installations in mingw mode

[Martin Storsjö via Phabricator via llvm-commits]

mstorsjo added a comment.

In D144084#4140157 <https://reviews.llvm.org/D144084#4140157>, @mati865 wrote:

> Should that even be considered as supported?

That's a good question... The flag in itself unlocks a whole bunch of behaviours, some which can be considered useful, and some probably just as tolerable sideeffects (like adding list markers for `__CTOR_LIST__` and such) - so in general I guess it's a bit iffy. I have mentioned the flag to various people throughout the years that they can try it out to see if it gives a behaviour they need though.

For some behaviours, there are individual flags that control the behaviours (like `-stdcall-fixup` or `-auto-import`) where the default behaviour depends on whether the mingw flag is set - but there are also lots of behaviours that aren't individually controllable.

I'm not sure what would be best here - add a more specific `-tolerate-duplicate-weak-sybols` option or something like that? Or add a more specific flag, always passed by default by the mingw driver frontend, e.g. `-detect-msvc:no`?

For context - I haven't heard about a specific case where this would make any difference, I just noticed the fact that this is done unconditionally - and there's a small risk that someone ends up relying on implicitly linking in things from a WinSDK they have lying around.


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