simplify some proc_macro things

[cyrgani]

Each commit should be reviewable on its own. Locally, this also resulted in some slightly better perf results.

[rustbot]

rust-analyzer is developed in its own repository. If possible, consider making this change to rust-lang/rust-analyzer instead.

cc @rust-lang/rust-analyzer

[rustbot]

r? @petrochenkov

rustbot has assigned @petrochenkov.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

Why was this reviewer chosen?

The reviewer was selected based on:

• Owners of files modified in this PR: @petrochenkov

[Kobzol]

@bors try @rust-timer queue

[rust-bors]

☀️ Try build successful (CI)
Build commit: aba743d (aba743d72e1a2d02bf787988ac919c3c416f243c, parent: c0bb140a37c81cf59a0b40c21c9413059644e294)

[rust-timer]

Finished benchmarking commit (aba743d): comparison URL.

Overall result: ❌✅ regressions and improvements - please read:

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

@bors rollup=never
@rustbot label: -S-waiting-on-perf +perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	0.4%	[0.1%, 1.1%]	27
Regressions ❌ (secondary)	0.2%	[0.2%, 0.2%]	1
Improvements ✅ (primary)	-0.8%	[-1.9%, -0.2%]	13
Improvements ✅ (secondary)	-1.9%	[-4.2%, -0.1%]	13
All ❌✅ (primary)	-0.0%	[-1.9%, 1.1%]	40

Max RSS (memory usage)

Results (primary 2.4%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	2.4%	[2.4%, 2.4%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.4%	[2.4%, 2.4%]	1

Cycles

Results (primary 0.4%, secondary -5.6%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	1.9%	[1.7%, 2.1%]	2
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.7%	[-2.7%, -2.7%]	1
Improvements ✅ (secondary)	-5.6%	[-5.6%, -5.6%]	1
All ❌✅ (primary)	0.4%	[-2.7%, 2.1%]	3

Binary size

Results (primary -0.9%, secondary -2.1%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.9%	[-1.3%, -0.4%]	17
Improvements ✅ (secondary)	-2.1%	[-3.0%, -0.4%]	7
All ❌✅ (primary)	-0.9%	[-1.3%, -0.4%]	17

Bootstrap: 511.375s -> 517.888s (1.27%)
Artifact size: 400.63 MiB -> 400.68 MiB (0.01%)

[cyrgani]

this should be perf-neutral now since all relevant commits either got dropped or moved into their own PRs