[experiment] try to enable TrustedLen for (old) thin vec

[panstromek]

This looks like it causes a regression, I want to test this out.

[panstromek]

@bors try @rust-timer queue

[rust-bors]

☀️ Try build successful (CI)
Build commit: 5b1716f (5b1716f92e28028e065b2c4a37545adf9bafe7ca)
Base parent: dfbea5b (dfbea5bc945a9d7ff017d3d4bfbd1af9295fe5b8)

[rust-timer]

Finished benchmarking commit (5b1716f): 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 rustc-perf
@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)	0.6%	[0.2%, 2.5%]	16
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (secondary -2.6%)

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)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-2.6%	[-2.6%, -2.6%]	1
All ❌✅ (primary)	-	-	0

Cycles

Results (secondary 4.2%)

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)	4.2%	[2.2%, 6.2%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 486.74s -> 494.477s (1.59%)
Artifact size: 387.74 MiB -> 387.65 MiB (-0.02%)

[panstromek]

@bors try @rust-timer queue

[rust-log-analyzer]

The job pr-check-2 failed! Check out the build log: (web) (plain enhanced) (plain)

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

[RUSTC-TIMING] rustc_public_bridge test:false 0.775
    Checking rustc_public v0.1.0-preview (/checkout/compiler/rustc_public)
[RUSTC-TIMING] rustc_public test:false 5.780
[RUSTC-TIMING] rustc_resolve test:false 9.506
error: usage of `.skip(0)`
   --> compiler/rustc_trait_selection/src/solve/fulfill.rs:197:19
    |
197 |             .skip(0)
    |                   ^ help: if you meant to skip the first element, use: `1`
    |

[rust-bors]

☀️ Try build successful (CI)
Build commit: 30d7a93 (30d7a9301d1b59b7544ec3fb4f4c35b107b2f0a4)
Base parent: 4fefe36 (4fefe3656700e5528edddc2336667818917dfc70)

[rust-timer]

Finished benchmarking commit (30d7a93): comparison URL.

Overall result: ❌ regressions - no action needed

Benchmarking means the PR may be perf-sensitive. Consider adding rollup=never if this change is not fit for rolling up.

@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)	0.2%	[0.2%, 0.2%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -1.3%, secondary 2.3%)

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)	2.3%	[2.3%, 2.3%]	1
Improvements ✅ (primary)	-1.3%	[-1.3%, -1.3%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-1.3%	[-1.3%, -1.3%]	1

Cycles

Results (secondary 4.8%)

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)	4.8%	[4.8%, 4.8%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 488.598s -> 487.536s (-0.22%)
Artifact size: 387.98 MiB -> 388.01 MiB (0.01%)

[rust-bors]

☔ The latest upstream changes (presumably #160005) made this pull request unmergeable. Please resolve the merge conflicts by rebasing.