buildkite: set common environment variables in env section

[mina86]

No description provided.

[matklad]

❤️

This have been bothering me for ages, would be great if it works (I didn't find this in buildkite's docs)

[matklad]

-W unreachable-pub will probably break every crate of ours. I do think it's a generally good thing to have, but I am not sure if it's good enough to actually enable for our use-case. But this should be a great way to test if this actually works.

To expand on this: things about logical organization (#5516) feel like they should maybe go before mechanical organization (-W unreachable-pub), and also -W unreachable-pub is buggy in the compiler, and sometimes requires work-arounds.

[matklad]

If we want to poach from rust-analyzer, than CARGO_INCREMENTAL=0 might be interesting avenue to explore to speed up CI: https://matklad.github.io/2021/09/04/fast-rust-builds.html#ci-caching. Needs substantial investigation though

[mina86]

We do multiple cargo invocations in ‘sanity checks’ so CARGO_INCREMENTAL=0 might be a bad idea in that particular step. For other steps it probably makes sense.

[matklad]

My mental model of how CARGO_INCREMENTAL=0 says that it orthogonal to "several cargo invocations".

CARGO_INCREMENTAL controls "less than compilation unit" granularity of incremental compilation: when you edit a single function, incremental compilation might allow the compiler to compile the crate with the change faster. Such fine grained incremental compilation needs a bit more CPU time, and a lot more of space on hard-drive, and setting CARGO_INCREMENTAL to zero disables that overhead.

Cross-crate instrumental compilation (your usual Makefile model with .o files) always works, even with CARGO_INCREMENTAL=0.

My understanding that fine-grained incremental compilation doesn't help with making cargo build --feature foo && cargo build --feature bar faster -- compiler doesn't share cached queries between the two invocations, it only shares queries for the same invocation, but different source code.

[matklad]

Hey, it does work, 🎉

Compiling proc-macro-crate v0.1.5
--
  | error: unreachable `pub` field
  | --> tools/rpctypegen/macro/src/lib.rs:16:5
  | \|
  | 16 \|     pub schema: BTreeMap<String, ErrorType>,
  | \|     ---^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

https://buildkite.com/nearprotocol/nearcore/builds/13184#6ce34762-ad12-491a-b85e-4d5b151d406f/94-443