borrowck: Make ConstraintCategory::CallArgument diagnostics pinpoint specific args

[Enselic]

Before this commit, ConstraintCategory::CallArgument diagnostics would point to the entire call expression:

LL |     let b = bar(f, y);
   |             ^^^^^^^^^ argument requires that `'a` must outlive `'b`

This commit changes the diagnostics to point to the specific argument that is causing the lifetime issue:

LL |     let b = bar(f, y);
   |                    ^ argument requires that `'a` must outlive `'b`

Draft

This is just a draft and not ready for review. (Although if someone says "this will never work because of ..." I would like to hear that, of course)

I am currently primarily interested in running perf on this, to get a sense for is this can be made to work. If not, there are hopefully other ways to achieve the same end result.

[Enselic]

@bors try @rust-timer queue

[rust-bors]

☀️ Try build successful (CI)
Build commit: 59ef33b (59ef33b6576cd200d3050ec6127e05704865762a)
Base parent: 3664b37 (3664b37017c529cad0f0ed259769f15743c21a6a)

[rust-timer]

Finished benchmarking commit (59ef33b): comparison URL.

Overall result: ❌ regressions - please read:

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.

Next, please: If you can, justify the regressions found in this try perf run in writing along with @rustbot label: +perf-regression-triaged. If not, fix the regressions and do another perf run. Neutral or positive results will clear the label automatically.

@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)	0.2%	[0.2%, 0.3%]	6
Regressions ❌ (secondary)	0.1%	[0.1%, 0.2%]	6
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.2%	[0.2%, 0.3%]	6

Max RSS (memory usage)

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

Cycles

Results (secondary -4.5%)

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)	2.1%	[2.1%, 2.1%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-11.1%	[-11.1%, -11.1%]	1
All ❌✅ (primary)	-	-	0

Binary size

Results (primary 0.1%, 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)	0.1%	[0.0%, 0.1%]	59
Regressions ❌ (secondary)	0.1%	[0.0%, 0.1%]	22
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.1%	[0.0%, 0.1%]	59

Bootstrap: 487.967s -> 489.278s (0.27%)
Artifact size: 388.37 MiB -> 388.89 MiB (0.14%)

[rustbot]

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

cc @rust-lang/clippy

[Enselic]

Sorry, fat thumbs on a smartphone made me accidentally click the "ready" button...