internal: Utilize cargo check --compile-time-deps

[ShoyuVanilla]

rust-lang/cargo#15674 has been merged and I guess it would be available in toolchain 1.90.0

I've tested this on rust-analyzer itself with cargo binary built from current master with the following my rust-analyzer branch
https://github.com/ShoyuVanilla/rust-analyzer/tree/comp-time-deps-test
and these are the results (I had run cargo clean before each run and modified the code a bit to use --compile-time-deps with injected cargo binary path iff env var $CARGO_BIN_FOR_TEST is set)

With --compile-time-deps

Without --compile-time-deps

Comparison

	analysis-stat results	Time	target dir size
--compile-time-deps	Identical	2m 25s	347 M
default	Identical	2m 55s	1.4 G

System Information

[lnicola]

😍

[edwin0cheng]

Do we want to disable RUSTC_WRAPPER too ?

[Veykril]

We should not set the wrapper if we use the flag

[ShoyuVanilla]

Do we want to disable RUSTC_WRAPPER too ?

Oh, I missed it. Thanks!

[Veykril]

This is amazing, can't wait to get rid of the wrapper in the future

[bjorn3]

Does this work in the rust-lang/rust workspace too?

[ShoyuVanilla]

Does this work in the rust-lang/rust workspace too?

Haven't tested in it yet but I guess so?

[bjorn3]

We set rust-analyzer.cargo.buildScripts.overrideCommand to ./x.py check --json-output. ./x.py check --json-output -Zunstable-options --compile-time-deps is not a valid command, which makes it seem to me like cargo_comp_time_deps_available is false (maybe toolchain is even None). We should probably add support for --compile-time-deps to x.py and then we could set it in the rust-analyzer config, but at the same time rust-analyzer should avoid setting RUSTC_WRAPPER.

[ShoyuVanilla]

Oh, I forgot about those x scripts in rust. Currently rust-analyzer is not appending --compile-time-deps when overrideCommands is set. #20121 (And setting that also ignores RUSTC_WRAPPER, so I guess currently in rust-lang/rust, neither --compile-time-deps nor RUSTC_WRAPPER is executed and thus full cargo check is happening 🙃 )

So, adding supports for --compile-time-deps to ./x.py sounds just enough to me.

[bjorn3]

Opened rust-lang/rust#143785. Saves a lot of time!

[ShoyuVanilla]

That's way better than my naive expectations 🎉