Bootstrap re-builds everything after "x.py check"

[RalfJung]

Some time over the last days, this started happening:

$ ./x.py test ui --bless -- null
$ ./x.py check miri
$ ./x.py test ui --bless -- null

The third invocation should finish immediately, but instead it rebuilds everything. So what is usually a 1s edit-test cycle now takes a full minute.

Cc @rust-lang/bootstrap

[onur-ozkan]

I wonder if #128871 has anything to do with this.

[RalfJung]

Yeah that sounds likely. Configuring the linker sets some env vars and when those differ between check and test builds, everything gets rebuilt.

[RalfJung]

Should we revert that PR then? Or is there some other short-term fix?

This is a significant hurdle for rustc development right now.

[Kobzol]

I suppose that we could for now just skip the check command from #128871. I tried the three commands that you have posted, and the last command did not rebuild anything (or rather, everything was fresh). What code should I modify between running these commands to reproduce the behavior that the third command rebuilds a lot of stuff?

[Kobzol]

Nevermind, I reproduced it. And the fix with removing check from configuring the linker works. I'll send a PR.

[onur-ozkan]

I think excluding check is quite good short-term fix.