Remove attribute parsing Stage

[JonathanBrouwer]

I discovered that it is surprisingly easy to remove the concept of Stage in the attribute parsers, imo this makes the code a lot cleaner.

r? @jdonszelmann
cc @mejrs @Bryntet

[JonathanBrouwer]

@bors try @rust-timer queue

[rust-bors]

☀️ Try build successful (CI)
Build commit: 0f16d2c (0f16d2c2b65c0f611f58ef7ec91415060e26d515, parent: fb76025f2fe6a1c8ce03fe0931f941c8077a2c34)

[rust-timer]

Finished benchmarking commit (0f16d2c): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

This perf run didn't have relevant results for this metric.

Max RSS (memory usage)

Results (secondary 6.1%)

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)	6.1%	[6.0%, 6.3%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Cycles

Results (secondary 2.6%)

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)	2.6%	[2.6%, 2.6%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

Results (secondary 0.1%)

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)	0.1%	[0.1%, 0.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Bootstrap: 487.131s -> 486.905s (-0.05%)
Artifact size: 394.07 MiB -> 394.02 MiB (-0.01%)

[JonathanBrouwer]

@bors try @rust-timer queue
Made some more changes, so lets rerun to be sure

[rustbot]

Some changes occurred in compiler/rustc_passes/src/check_attr.rs

cc @jdonszelmann

Some changes occurred to diagnostic attributes.

cc @mejrs

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann

[Bryntet]

Wow this is a very nice change!!

[rust-bors]

☀️ Try build successful (CI)
Build commit: 1605ec0 (1605ec0500eb4d5265572f443e427b9ceb0d6307, parent: fb76025f2fe6a1c8ce03fe0931f941c8077a2c34)

[rust-timer]

Finished benchmarking commit (1605ec0): comparison URL.

Overall result: ✅ improvements - no action needed

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.

@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
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-0.2%	[-0.3%, -0.2%]	2
Improvements ✅ (secondary)	-0.5%	[-0.6%, -0.3%]	8
All ❌✅ (primary)	-0.2%	[-0.3%, -0.2%]	2

Max RSS (memory usage)

Results (primary -0.7%, secondary 1.1%)

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

	mean	range	count
Regressions ❌ (primary)	0.6%	[0.6%, 0.6%]	1
Regressions ❌ (secondary)	6.2%	[5.9%, 6.5%]	2
Improvements ✅ (primary)	-2.1%	[-2.1%, -2.1%]	1
Improvements ✅ (secondary)	-2.3%	[-2.5%, -2.1%]	3
All ❌✅ (primary)	-0.7%	[-2.1%, 0.6%]	2

Cycles

Results (primary 2.4%, secondary 0.6%)

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)	2.5%	[2.0%, 3.0%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.1%	[-3.1%, -3.1%]	1
All ❌✅ (primary)	2.4%	[2.4%, 2.4%]	1

Binary size

Results (secondary 0.1%)

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)	0.1%	[0.1%, 0.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Bootstrap: 487.131s -> 488.391s (0.26%)
Artifact size: 394.07 MiB -> 393.58 MiB (-0.12%)

[rustbot]

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.