Try to use approximate placeholder regions when outputting an AscribeUserType error in borrowck

[jackh726]

Fixes #114866

Hi from GOSIM :)

[rustbot]

r? @wesleywiser

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

[compiler-errors]

I'm not sure if I consider this an improvement over "higher ranked lifetime error".

[jackh726]

Yeah, the note is not all that helpful. But its actually very similar to our pre-NLL error (see output on 1.64).

I consider this more of a "get us back to where we were" than a "this is the best we can do"

[jackh726]

The "one type is more general than the other" note is the most helpful part of the diagnostic, and I think that's an improvement over "higher-ranked lifetime error" alone.

[compiler-errors]

Why do we end up reporting this?

[jackh726]

I'm not sure :) seems like something with our lowering isn't quite right. I've seen something similar before, I think.

[jackh726]

@rustbot ready

[wesleywiser]

r? @compiler-errors

Would you mind taking another look at this? I'm not sure if your initial feedback has all been resolved as you expect or not.

[compiler-errors]

@bors r+

I still don't think I agree that this PR is better but whatever

[bors]

📌 Commit 35dd0c9 has been approved by compiler-errors

It is now in the queue for this repository.

[bors]

⌛ Testing commit 35dd0c9 with merge 820f06b...

[bors]

☀️ Test successful - checks-actions
Approved by: compiler-errors
Pushing 820f06b to master...

[rust-timer]

Finished benchmarking commit (820f06b): 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)	0.5%	[0.5%, 0.5%]	1
Regressions ❌ (secondary)	2.3%	[2.3%, 2.3%]	1
Improvements ✅ (primary)	-0.7%	[-0.9%, -0.4%]	5
Improvements ✅ (secondary)	-3.9%	[-3.9%, -3.9%]	1
All ❌✅ (primary)	-0.5%	[-0.9%, 0.5%]	6

Cycles

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

Binary size

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

Bootstrap: 674.025s -> 675.791s (0.26%)
Artifact size: 313.64 MiB -> 313.65 MiB (0.00%)