[PATCH] D66834: Driver tests: set `--sysroot=""` to support clang with `DEFAULT_SYSROOT`

[Serge Pavlov via Phabricator via cfe-commits]

sepavloff accepted this revision.
sepavloff added a comment.
This revision is now accepted and ready to land.

In D66834#1685921 <https://reviews.llvm.org/D66834#1685921>, @broadwaylamb wrote:

> In D66834#1685260 <https://reviews.llvm.org/D66834#1685260>, @sepavloff wrote:
>
> > In D66834#1653334 <https://reviews.llvm.org/D66834#1653334>, @broadwaylamb wrote:
> >
> > > In D66834#1652756 <https://reviews.llvm.org/D66834#1652756>, @compnerd wrote:
> > >
> > > > I think that this is pretty easy to forget.  Fortunately, last argument wins.  Why not sink this into the `%clang` substitution in lit?  That ensures that we run with an empty sysroot and then when the test needs to adjust the sysroot, it can do so explicitly.
> > >
> > >
> > > I've just tried to do it, but unfortunately some tests are failing, for example, `Driver/cc1-response-files.c`. The problem is that `%clang` is expanded to `/path/to/clang --sysroot=`, but the succeeding flags (such as `-cc1`) may be incompatible with `--sysroot`.
> >
> >
> > Does the issue manifests itself with `-cc1` only? We usually use `%clang_cc1` in such cases, so probably those tests require update.
>
>
> Some Driver tests take a list of arguments from a file (for example `clang/test/Driver/cc1-response-files.c`), so we probably cannot use `%clang_cc1` there


The obvious solution in this case is to implement support of an environment variable, say `SYSROOT` or `CLANG_SYSROOT`, which would override hard-coded path (but not that specified by --sysroot option). Unfortunately some developers don't like use of environment variables, as it creates 'secret' control channel, and such patch would have high chance to be rejected. So probably this is all we can do here.

This patch looks good for me.


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https://reviews.llvm.org/D66834