rustc_expand: improve diagnostics for non-repeatable metavars

[Unique-Usman]

There was an initally opened pr which solve this issue here #152679. It got merged but, there was a perf regression. And this new pr is opened to address the problem. The first did the computation of binding and matched_rule and then passed them as owned value down to diagnostics::emit_frag_parse_err( but, now this pr address the issue by passing lhs and rules as borrowed value to from_tts and the move the logic to diagnostics::emit_frag_parse_err(.

Fix #47452.

[rustbot]

r? @adwinwhite

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[Unique-Usman]

r? @estebank

[estebank]

@bors try @rust-timer queue

[rust-bors]

☀️ Try build successful (CI)
Build commit: c7819c5 (c7819c57c7c6744e29582575ea34a29d6e8a3905, parent: 13e2abaac846b2680ae93e1b3bd9fe7fe1b9a7fe)

[rust-timer]

Finished benchmarking commit (c7819c5): comparison URL.

Overall result: ❌ regressions - please read the text below

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.

Next Steps: If you can justify the regressions found in this try perf run, please do so in sufficient writing along with @rustbot label: +perf-regression-triaged. If not, please fix the regressions and do another perf run. If its results are neutral or positive, the label will be automatically removed.

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

Max RSS (memory usage)

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

Cycles

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)	1.9%	[1.9%, 1.9%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.9%	[-2.9%, -2.9%]	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%]	55
Regressions ❌ (secondary)	0.1%	[0.0%, 0.2%]	24
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	0.1%	[0.0%, 0.1%]	55

Bootstrap: 482.731s -> 482.467s (-0.05%)
Artifact size: 396.84 MiB -> 396.93 MiB (0.02%)

[estebank]

The regressions here are all in html5ever. I think this should be fine.

@Unique-Usman could you provide a description, a link to the previous PR and squash the commits?

[Unique-Usman]

@estebank, I will do that. Thanks.