Use tracing spans in rustc_trait_selection

[matthewjasper]

Spans are very helpful when debugging this code. It's also hot enough to make a good benchmark.

r? @oli-obk

[matthewjasper]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion

[bors]

⌛ Trying commit 33566e3c4d5c128db222179e0fd0ea4ac7deff27 with merge 33f17791eda83acb9da4fee1c76dda7d9a630c7f...

[bors]

☀️ Try build successful - checks-actions, checks-azure
Build commit: 33f17791eda83acb9da4fee1c76dda7d9a630c7f (33f17791eda83acb9da4fee1c76dda7d9a630c7f)

[rust-timer]

Queued 33f17791eda83acb9da4fee1c76dda7d9a630c7f with parent 87b71ed, future comparison URL.

[rust-timer]

Finished benchmarking try commit (33f17791eda83acb9da4fee1c76dda7d9a630c7f): comparison url.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. Please note that if the perf results are neutral, you should likely undo the rollup=never given below by specifying rollup- to bors.

Importantly, though, if the results of this run are non-neutral do not roll this PR up -- it will mask other regressions or improvements in the roll up.

@bors rollup=never

[matthewjasper]

This is up to a 0.8% regression. I'll see if reducing the number of spans being used can help here.

[matthewjasper]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion

[bors]

⌛ Trying commit a555e3e018d4bae90448e51f4ce34bad3da3376d with merge 021a682eb34f6400e8cf300121d1b4a28f6267e3...

[rust-log-analyzer]

The job dist-x86_64-linux of your PR failed (pretty log, raw log). Through arcane magic we have determined that the following fragments from the build log may contain information about the problem.

Click to expand the log.

   Compiling rustc_trait_selection v0.0.0 (/checkout/compiler/rustc_trait_selection)
error: expected expression, found `?`
   --> compiler/rustc_trait_selection/src/traits/fulfill.rs:346:38
    |
346 |         debug!("process_obligation", ?obligation, ?obligation.cause);
    |                                      ^ expected expression
error: aborting due to previous error

error: could not compile `rustc_trait_selection`


To learn more, run the command again with --verbose.
warning: build failed, waiting for other jobs to finish...
error: build failed
command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "build" "--target" "x86_64-unknown-linux-gnu" "-Zbinary-dep-depinfo" "-j" "16" "--release" "--locked" "--color" "always" "--features" "jemalloc llvm max_level_info" "--manifest-path" "/checkout/compiler/rustc/Cargo.toml" "--message-format" "json-render-diagnostics"
failed to run: /checkout/obj/build/bootstrap/debug/bootstrap dist --host x86_64-unknown-linux-gnu --target x86_64-unknown-linux-gnu
Build completed unsuccessfully in 0:11:36
== clock drift check ==
  local time: Sun Oct 11 10:53:11 UTC 2020
  local time: Sun Oct 11 10:53:11 UTC 2020
  network time: Sun, 11 Oct 2020 10:53:12 GMT
== end clock drift check ==
##[error]Process completed with exit code 1.
Terminate orphan process: pid (4653) (python)

I'm a bot! I can only do what humans tell me to, so if this was not helpful or you have suggestions for improvements, please ping or otherwise contact @rust-lang/infra. (Feature Requests)

[bors]

💔 Test failed - checks-actions

[matthewjasper]

@bors try @rust-timer queue

[rust-timer]

Awaiting bors try build completion

[bors]

⌛ Trying commit b8d2560 with merge 3cb8bc741b28e59fb753232e99ce1d235fd6c713...

[bors]

☀️ Try build successful - checks-actions, checks-azure
Build commit: 3cb8bc741b28e59fb753232e99ce1d235fd6c713 (3cb8bc741b28e59fb753232e99ce1d235fd6c713)

[rust-timer]

Queued 3cb8bc741b28e59fb753232e99ce1d235fd6c713 with parent 8cc82ee, future comparison URL.

[rust-timer]

Finished benchmarking try commit (3cb8bc741b28e59fb753232e99ce1d235fd6c713): comparison url.

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. Please note that if the perf results are neutral, you should likely undo the rollup=never given below by specifying rollup- to bors.

Importantly, though, if the results of this run are non-neutral do not roll this PR up -- it will mask other regressions or improvements in the roll up.

@bors rollup=never

[oli-obk]

@bors r+

looks like we actually got a small perf improvement out of it

[bors]

📌 Commit b8d2560 has been approved by oli-obk

[bors]

⌛ Testing commit b8d2560 with merge abbdec3...

[bors]

☀️ Test successful - checks-actions, checks-azure
Approved by: oli-obk
Pushing abbdec3 to master...

[Mark-Simulacrum]

Final results confirm the perf improvement.