On Fn arg mismatch for a fn path, suggest a closure

[estebank]

When encountering a fn call that has a path to another fn being passed in, where an Fn impl is expected, and the arguments differ, suggest wrapping the argument with a closure with the appropriate arguments.

The last help is new:

error[E0631]: type mismatch in function arguments
  --> $DIR/E0631.rs:9:9
   |
LL |     fn f(_: u64) {}
   |     ------------ found signature defined here
...
LL |     foo(f);
   |     --- ^ expected due to this
   |     |
   |     required by a bound introduced by this call
   |
   = note: expected function signature `fn(usize) -> _`
              found function signature `fn(u64) -> _`
note: required by a bound in `foo`
  --> $DIR/E0631.rs:3:11
   |
LL | fn foo<F: Fn(usize)>(_: F) {}
   |           ^^^^^^^^^ required by this bound in `foo`
help: consider wrapping the function in a closure
   |
LL |     foo(|arg0: usize| f(/* u64 */));
   |         +++++++++++++  +++++++++++

[rustbot]

r? @petrochenkov

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

[petrochenkov]

@bors r+

[bors]

📌 Commit 25c75bc has been approved by petrochenkov

It is now in the queue for this repository.

[bors]

⌛ Testing commit 25c75bc with merge 87e1447...

[bors]

☀️ Test successful - checks-actions
Approved by: petrochenkov
Pushing 87e1447 to master...

[rust-timer]

Finished benchmarking commit (87e1447): comparison URL.

Overall result: ✅ improvements - no action needed

@rustbot label: -perf-regression

Instruction count

This is a highly reliable metric that was 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)	-0.3%	[-0.3%, -0.3%]	1
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

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

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)	17.7%	[10.2%, 27.4%]	7
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	17.7%	[10.2%, 27.4%]	7

Binary size

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

Bootstrap: 673.226s -> 674.44s (0.18%)
Artifact size: 313.37 MiB -> 313.39 MiB (0.01%)