[perf] Cache structural resolution in typeck

[compiler-errors]

🤷

[compiler-errors]

@bors2 try @rust-timer queue

[rust-bors]

⌛ Trying commit b835a90 with merge c778a3d…

To cancel the try build, run the command @bors2 try cancel.

[rust-log-analyzer]

The job mingw-check-tidy failed! Check out the build log: (web) (plain)

Click to see the possible cause of the failure (guessed by this bot)

##[endgroup]
Executing TIDY_PRINT_DIFF=1 npm install eslint@$(head -n 1 /tmp/eslint.version) &&  python2.7 ../x.py test --stage 0 src/tools/tidy tidyselftest --extra-checks=py,cpp
+ head -n 1 /tmp/eslint.version
+ TIDY_PRINT_DIFF=1 npm install [email protected]
npm ERR! code E504
npm ERR! 504 Gateway Timeout - GET https://registry.npmjs.org/@humanwhocodes%2fobject-schema

npm ERR! A complete log of this run can be found in: /home/user/.npm/_logs/2025-06-12T19_04_53_057Z-debug-0.log
  local time: Thu Jun 12 19:08:58 UTC 2025
  network time: Thu, 12 Jun 2025 19:08:58 GMT
##[error]Process completed with exit code 1.
Post job cleanup.

[rust-bors]

☀️ Try build successful (CI)
Build commit: c778a3d (c778a3d429fbc40690c35552d0f1ea3f2a2ab64f, parent: 6c8138de8f1c96b2f66adbbc0e37c73525444750)

[rust-timer]

Finished benchmarking commit (c778a3d): comparison URL.

Overall result: ✅ improvements - 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

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.7%	[-1.3%, -0.2%]	7
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 1.6%, secondary -5.8%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	1.6%	[1.6%, 1.6%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-5.8%	[-5.8%, -5.8%]	1
All ❌✅ (primary)	1.6%	[1.6%, 1.6%]	1

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: 754.987s -> 756.054s (0.14%)
Artifact size: 372.08 MiB -> 372.20 MiB (0.03%)

[compiler-errors]

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