avoid &mut P<T> in visit_expr etc methods

[fee1-dead]

trying a different way than #141636
r? ghost

[fee1-dead]

@bors try @rust-timer queue

[bors]

⌛ Trying commit acf4046 with merge c2996b4...

[bors]

☀️ Try build successful - checks-actions
Build commit: c2996b4 (c2996b4a102c36e4be0fce51b8ef97d407a3a080)

[rust-timer]

Finished benchmarking commit (c2996b4): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

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

Instruction count

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

Max RSS (memory usage)

Results (secondary -0.5%)

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)	1.0%	[1.0%, 1.0%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.1%	[-2.1%, -2.1%]	1
All ❌✅ (primary)	-	-	0

Cycles

Results (secondary -2.5%)

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
Improvements ✅ (secondary)	-2.5%	[-2.5%, -2.5%]	1
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 755.487s -> 754.164s (-0.18%)
Artifact size: 372.14 MiB -> 372.12 MiB (-0.00%)

[rustbot]

Some changes occurred in src/tools/clippy

cc @rust-lang/clippy