tests: disable incremental compilation in dogfood to reduce target dir size

[matthiaskrgr]

tests: execute dogfood tests with incremental compilation disabled reduces target/ dir size of when "cargo test"ing by around 2 gigs.

changelog: none

[llogiq]

I tried this, and it appeared to slow down the inevitable "no space left on device", though not overcoming it. The dogfood_tests test seems to generate a lot of data on disk.

[llogiq]

Interestingly, if I run cargo build && for d in clippy_workspace_tests clippy_workspace_tests/src clippy_workspace_tests/subcrate clippy_workspace_tests/subcrate/src clippy_dev rustc_tools_util; do CLIPPY_DOGFOOD=1 target/debug/cargo-clippy clippy --verbose -- -D clippy::all -D clippy::pedantic; done from a clean repo, it "only" takes about 5G.

Perhaps a way to clear the incremental caches between dogfood and dogfood_tests would give us sufficient wins without losing all of the benefits of incremental compilation.

[matthiaskrgr]

clear the incremental caches between dogfood and dogfood_tests

Hmm, I think the tests currently run in parallel, so we'd have to run them in linear order which will probably worsen execution time.

[matthiaskrgr]

Clippy seems to invoke rustc with -C debuginfo=2 and I wonder how much that adds to the target dir size.
Is there a way to override it?
RUSTFLAGS ="-Cdebuginfo=0" or cargo clippy -- -Cdebuginfo=0 does not seem to work.

EDIT: nevermind it seems to work, pebkac.

[matthiaskrgr]

previous behaviour:

cargo build
time cargo test
time: 1147 seconds
size target dir: 6503 m
// change a string inside clippy to trigger incr comp
time cargo test
time: 155 seconds
size: 6837 m

with this branch:

cargo build
time cargo test
time: 993 s
size target dir: 4146 m
// change string
time cargo test
time: 230 seconds
size target dir: 4479

[flip1995]

Seems good to me. Just deleted a 50GB target directory from Clippy yesterday.

[llogiq]

@bors r+

[bors]

📌 Commit a1ecf39 has been approved by llogiq

[bors]

⌛ Testing commit a1ecf39 with merge 535bc1d...

[bors]

☀️ Test successful - checks-travis, status-appveyor
Approved by: llogiq
Pushing 535bc1d to master...

[llogiq]

Thanks, @matthiaskrgr!