Store the names of Fn trait parameters in the AST, fix rustfmt bug

[JonathanBrouwer]

This PR stores the name of a Fn trait parameters in the AST. This is needed because

• rustfmt needs to rewrite it.
• this will also be needed in a follow-up PR to do semantic validation.

This PR is split up in commits for reviewability:

• Make inputs to ParenthesizedArgs a ThinVec<Param> in the compiler changes the AST datatypes, should have no observable effect
• Fix errors in tooling deals with the consequenses of the first commit in tooling, should have no observable effect
• Improve rewrite_generic_args to take pattern into account fixes rustfmt emits non-compiling code by removing tokens from function-like macro invocations rustfmt#7021
• Add rustfmt regression test regression test for rustfmt emits non-compiling code by removing tokens from function-like macro invocations rustfmt#7021

I have not worked in the rustfmt codebase before so please review this part carefully.

Tracking issue: #158499
cc @ytmimi @JohnTitor

[rustbot]

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

cc @rust-lang/clippy

The parser was modified, potentially altering the grammar of (stable) Rust
which would be a breaking change.

cc @fmease

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

cc @rust-lang/rustfmt

[rustbot]

r? @ytmimi

rustbot has assigned @ytmimi.
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: rustfmt, rustfmt-contributors
• rustfmt, rustfmt-contributors expanded to 6 candidates
• Random selection from fee1-dead, jieyouxu, ytmimi

[JonathanBrouwer]

@bors try @rust-timer queue
This should not have any effect, but changing the AST representation (although only a small part of it) deserves a sanity check

[rust-bors]

☀️ Try build successful (CI)
Build commit: 0051041 (0051041425480d6ca5704480c6e5a31a5ed63824)
Base parent: e64c8a6 (e64c8a664d9da54fc239cd4404cbf67f0d624326)

[ytmimi]

@JonathanBrouwer Thank you, again. I took a look at the rustfmt code changes and they all look very straightforward to me. Having the rustfmt target test case there will help us avoid any regressions and make sure that the formatting stays idempotent.

Assuming that CI passes and the timing run doesn't show any performance impacts from this change you can r=me.

[rust-timer]

Finished benchmarking commit (0051041): 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 (primary 2.2%, secondary 0.2%)

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

	mean	range	count
Regressions ❌ (primary)	2.2%	[0.6%, 3.8%]	2
Regressions ❌ (secondary)	1.6%	[0.4%, 4.2%]	6
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.6%	[-1.1%, -0.4%]	10
All ❌✅ (primary)	2.2%	[0.6%, 3.8%]	2

Cycles

Results (primary 0.0%, secondary -0.0%)

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

	mean	range	count
Regressions ❌ (primary)	2.3%	[2.3%, 2.3%]	1
Regressions ❌ (secondary)	1.0%	[0.4%, 2.5%]	11
Improvements ✅ (primary)	-2.3%	[-2.3%, -2.3%]	1
Improvements ✅ (secondary)	-0.7%	[-1.6%, -0.4%]	16
All ❌✅ (primary)	0.0%	[-2.3%, 2.3%]	2

Binary size

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

Bootstrap: 455.693s -> 460.326s (1.02%)
Artifact size: 396.39 MiB -> 396.43 MiB (0.01%)

[JonathanBrouwer]

@bors r=ytmimi rollup

[rust-bors]

📌 Commit 2e63745 has been approved by ytmimi

It is now in the queue for this repository.