adjust how closure/generator types are printed

[RalfJung]

I saw &[closure@$DIR/issue-20862.rs:2:5] and I thought it is a slice type, because that's usually what &[_] is... it took me a while to realize that this is just a confusing printer and actually there's no slice. Let's use something that cannot be mistaken for a regular type.

[rustbot]

r? @petrochenkov

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

[RalfJung]

Hm, something somewhere is still printing [closure@...], I'm seeing it in some ui tests.

[RalfJung]

Ah, what I changed was actually the rvalue printing (which doesn't seem to be exercised by the test suite), not the type printing.

[rustbot]

The Miri subtree was changed

cc @rust-lang/miri

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy

[oli-obk]

Seems fine to me, please create an MCP for it so all of the compiler team gets informed about it.

[bors]

☔ The latest upstream changes (presumably #115661) made this pull request unmergeable. Please resolve the merge conflicts.

[RalfJung]

@oli-obk how long do we want to wait from the MCP seconding to landing the PR?

[oli-obk]

MCPs are 10 days

[bors]

☔ The latest upstream changes (presumably #115865) made this pull request unmergeable. Please resolve the merge conflicts.

[BoxyUwU]

the MCP has been accepted for 10 days now this can be merged after a rebase presumably

[oli-obk]

@bors r+

[bors]

📌 Commit c4ec12f has been approved by oli-obk

It is now in the queue for this repository.

[bors]

⌛ Testing commit c4ec12f with merge 959b2c7...

[bors]

☀️ Test successful - checks-actions
Approved by: oli-obk
Pushing 959b2c7 to master...

[rust-timer]

Finished benchmarking commit (959b2c7): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.0%	[-3.4%, -2.6%]	4
All ❌✅ (primary)	-	-	0

Cycles

Results

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.1%	[-2.1%, -2.1%]	1
All ❌✅ (primary)	-	-	0

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 633.528s -> 635.567s (0.32%)
Artifact size: 317.74 MiB -> 317.55 MiB (-0.06%)