download-rustc has no effect when running run-make tests

[lolbinarycat]

reproduction steps:

1. set rust.download-rustc = true in config.toml
2. run ./x test --stage 1 tests/run-make

expected behavior: rustc is downloaded

actually behavior: rustc and cargo are built from source

[Noratrieb]

Why do you want to run tests on the downloaded compiler?

[jieyouxu]

I don't quite understand this use case. COMPILETEST_FORCE_STAGE0=1 ./x test --stage 0 tests/run-make will run tests on a downloaded beta compiler, or otherwise a user-provided initial rustc (such as a previous stage2 compiler as part of opt-dist step). Running the tests on a beta compiler or an initial rustc that is older is not a supported use case in the general sense. Many run-make tests will fail. Having download-rustc = true mean the stage 1 rustc also getting downloaded makes no sense to me, you'll just run into the same test failures when you try to run the run-make tests with the aforementioned beta compiler.

Could you elaborate why you want this, or what this is in the context of?

[bjorn3]

If you only modified the standard library and want to run run-make tests to see if your change broke something, I would expect download-rustc be enough to avoid having to recompile the compiler itself. There is no need to recompile the compiler in that case as it wasn't modified.

[jieyouxu]

I see

[lolbinarycat]

Why do you want to run tests on the downloaded compiler?

in my case, i was trying to modify compiletest, but it also would be useful if you're modifying the tests themselves.

[jieyouxu]

in my case, i was trying to modify compiletest

For compiletest specifically, compiletest is a stage0 bootstrap tool, so you can just ./x test src/tools/compiletest --stage 0 to make it build (and run its unit tests). But yes, it could be helpful to have download-rustc working with the test suite as well.

[onur-ozkan]

Added to Tracking Issue for download-rustc improvements.