Remove the cstore reference from Session

[michaelwoerister]

This PR removes the CrateStore reference from Session in preparation to control all CrateStore access through the tcx. This control will later be used to either interpose a CrateStore wrapper for dependency tracking or forcing all CrateStore access to go through queries.

[rust-highfive]

r? @arielb1

(rust_highfive has picked a reviewer for you, use r? to override)

[michaelwoerister]

r? @nikomatsakis

[nikomatsakis]

@bors r+

[bors]

📌 Commit 27b50f6 has been approved by nikomatsakis

[arielb1]

[01:05:41] Compiling rustc v0.0.0 (file:///checkout/src/librustc)
[01:05:47] error: unused import: `DummyCrateStore`
[01:05:47] --> /checkout/src/librustc/session/config.rs:1954:32
[01:05:47] |
[01:05:47] 1954 | use middle::cstore::{self, DummyCrateStore};
[01:05:47] | ^^^^^^^^^^^^^^^
[01:05:47] |
[01:05:47] note: lint level defined here
[01:05:47] --> /checkout/src/librustc/lib.rs:20:9
[01:05:47] |
[01:05:47] 20 | #![deny(warnings)]
[01:05:47] | ^^^^^^^^
[01:05:47] = note: #[deny(unused_imports)] implied by #[deny(warnings)]
[01:05:47] [01:05:47] error: unused import: `std::rc::Rc`
[01:05:47] --> /checkout/src/librustc/session/config.rs:1960:9
[01:05:47] |
[01:05:47] 1960 | use std::rc::Rc;
[01:05:47] | ^^^^^^^^^^^
[01:05:47] 

@bors r-

[michaelwoerister]

@bors r=nikomatsakis

[bors]

📌 Commit ef96a41 has been approved by nikomatsakis

[Mark-Simulacrum]

@bors rollup

[Mark-Simulacrum]

@bors rollup- actually, this feels like it might have perf implications

[alexcrichton]

Note that this is also likely to conflict quite a bit with #44142, where I think a lot of the tcx.sess.cstore -> tcx.cstore() may no longer be necessary after that lands

[michaelwoerister]

@alexcrichton I don't mind holding off on this PR until #44142 is merged.

[alexcrichton]

@bors: r-

Ok gonna r- this until #44142 lands. I feel bad though as that's gonna be a nasty merge, so I went ahead and did it!

I rebased this commit in alexcrichton@a00804b and then tacked alexcrichton@e3e88cd on top which makes CrateStore entirely private, yay!

[michaelwoerister]

Thanks, @alexcrichton! I'll close this then in favor of #44142.

[alexcrichton]

I've reopened this as #44420