Make select_* methods return Vec for TraitEngine

[fee1-dead]

This reduces some complexity as an empty vec means no errors and non-empty vec means errors occurred.

[rust-highfive]

Some changes occurred in src/tools/clippy.

cc @rust-lang/clippy

[rust-highfive]

r? @davidtwco

(rust-highfive has picked a reviewer for you, use r? to override)

[fee1-dead]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion.

@rustbot label: +S-waiting-on-perf

[bors]

⌛ Trying commit f1126f1 with merge 3cbe0cbf58b7833e019afbf2c0254e556430c0ab...

[bors]

☀️ Try build successful - checks-actions
Build commit: 3cbe0cbf58b7833e019afbf2c0254e556430c0ab (3cbe0cbf58b7833e019afbf2c0254e556430c0ab)

[rust-timer]

Queued 3cbe0cbf58b7833e019afbf2c0254e556430c0ab with parent 3e3890c, future comparison URL.

[rust-timer]

Finished benchmarking commit (3cbe0cbf58b7833e019afbf2c0254e556430c0ab): comparison url.

Summary: This benchmark run did not return any relevant changes.

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR led to changes in compiler perf.

@bors rollup=never
@rustbot label: +S-waiting-on-review -S-waiting-on-perf -perf-regression

[jackh726]

Ooh I like.

[davidtwco]

@bors r+

[bors]

📌 Commit d863021 has been approved by davidtwco

[bors]

⌛ Testing commit d863021 with merge eee8b9c...

[bors]

☀️ Test successful - checks-actions
Approved by: davidtwco
Pushing eee8b9c to master...

[rust-timer]

Finished benchmarking commit (eee8b9c): comparison url.

Summary: This benchmark run did not return any relevant changes.

If you disagree with this performance assessment, please file an issue in rust-lang/rustc-perf.

@rustbot label: -perf-regression