[cfe-dev] Cannot CMake self-hosted clang on Windows for lack of libxml2

[Adrian McCarthy via cfe-dev]

>  Could an issue please be filed about this? CMake tries hard to not break
backwards compat, though we're not perfect (and we can't fix what we're
not aware of).

I appreciate that, but I don't think this is a CMake bug.

In this instance, llvm-mt is supposed to be a cross-platform drop-in
alternative for mt.exe.  In theory, it shouldn't matter which one CMake
selects.  And, in fact, the point of a self-hosted build is to use the LLVM
tool chain.  The fact that llvm-mt's dependencies aren't met on Windows
seems like an LLVM problem, either in the tool itself or in the
documentation about how to set up the development environment.

[Rant about the near-infinite size of LLVM's "supported" configuration
space elided, for now.]


On Mon, Aug 23, 2021 at 5:12 PM Ben Boeckel <ben.boeckel at kitware.com> wrote:

> On Mon, Aug 23, 2021 at 15:17:21 -0700, Adrian McCarthy via cfe-dev wrote:
> > Yikes!  Thanks for the heads up.
> >
> > This is the third time I've bisected to find build configuration problems
> > that affect only certain Windows configurations only to learn that it was
> > (primarily) a change in our tools that broke things (retroactively).
> Since
> > the bot configurations aren't updated very often, it's easy for these
> > problems to go unnoticed for a very long time.
>
> *Puts on CMake developer hat*
>
> Could an issue please be filed about this? CMake tries hard to not break
> backwards compat, though we're not perfect (and we can't fix what we're
> not aware of).
>
> > It's one thing not to have hermetic builds, but it's quite another to
> allow
> > every developer to choose from a wide range of versions for each of the
> > myriad tools necessary to build the product.  The builds are so sensitive
> > to so many details of the environment, it's rather amazing to me how
> often
> > we manage to succeed.
>
> Yes, and CMake tries not to be the bump in the road there, but we can
> fix this in 3.20.6 and 3.21.2 (maybe 3.21.3, depends on how intricate
> the fix is).
>
> Thanks,
>
> --Ben
>
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