Cleanup (pretty) printing of ty::Const

[oli-obk]

r? @eddyb

addresses https://github.com/rust-lang/rust/pull/59178/files/5cd28066214a4a255bac6655c20bf05cb95730fd#r266243236 and https://github.com/rust-lang/rust/pull/59178/files/5cd28066214a4a255bac6655c20bf05cb95730fd#r266243336

[bors]

☔ The latest upstream changes (presumably #59657) made this pull request unmergeable. Please resolve the merge conflicts.

[rust-highfive]

The job x86_64-gnu-llvm-6.0 of your PR failed on Travis (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.

travis_time:end:03cc1cf0:start=1554311126937002861,finish=1554311129349319038,duration=2412316177
$ git checkout -qf FETCH_HEAD
travis_fold:end:git.checkout

Encrypted environment variables have been removed for security reasons.
See https://docs.travis-ci.com/user/pull-requests/#pull-requests-and-security-restrictions
$ export SCCACHE_BUCKET=rust-lang-ci-sccache2
$ export SCCACHE_REGION=us-west-1
$ export GCP_CACHE_BUCKET=rust-lang-ci-cache
Setting environment variables from .travis.yml
---
[00:57:41]    Compiling rustdoc v0.0.0 (/checkout/src/librustdoc)
[00:57:44] error[E0308]: mismatched types
[00:57:44]     --> src/librustdoc/clean/mod.rs:2765:51
[00:57:44]      |
[00:57:44] 2765 |                     Ok(length) => print_const(cx, length),
[00:57:44]      |                                                   |
[00:57:44]      |                                                   expected struct `rustc::ty::Const`, found reference
[00:57:44]      |                                                   expected struct `rustc::ty::Const`, found reference
[00:57:44]      |                                                   help: consider dereferencing the borrow: `*length`
[00:57:44]      = note: expected type `rustc::ty::Const<'_>`
[00:57:44]                 found type `&rustc::ty::Const<'_>`
[00:57:44] 
[00:57:44] error[E0308]: mismatched types
[00:57:44] error[E0308]: mismatched types
[00:57:44]     --> src/librustdoc/clean/mod.rs:2960:29
[00:57:44]      |
[00:57:44] 2960 |                         n = new_n;
[00:57:44]      |                             ^^^^^
[00:57:44]      |                             |
[00:57:44]      |                             expected struct `rustc::ty::Const`, found reference
[00:57:44]      |                             help: consider dereferencing the borrow: `*new_n`
[00:57:44]      = note: expected type `rustc::ty::Const<'_>`
[00:57:44]                 found type `&rustc::ty::Const<'_>`
[00:57:44] 
[00:57:44] error[E0599]: no method named `to_string` found for type `rustc::ty::Const<'_>` in the current scope
[00:57:44] error[E0599]: no method named `to_string` found for type `rustc::ty::Const<'_>` in the current scope
[00:57:44]     --> src/librustdoc/clean/mod.rs:4142:27
[00:57:44]      |
[00:57:44] 4142 |             let mut s = n.to_string();
[00:57:44]      |
[00:57:44]      = note: the method `to_string` exists but the following trait bounds were not satisfied:
[00:57:44]              `rustc::ty::Const<'_> : std::string::ToString`
[00:57:44] 
---
travis_time:end:17fb976e:start=1554314609057925204,finish=1554314609063103580,duration=5178376
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:2a0f13f2
$ ln -s . checkout && for CORE in obj/cores/core.*; do EXE=$(echo $CORE | sed 's|obj/cores/core\.[0-9]*\.!checkout!\(.*\)|\1|;y|!|/|'); if [ -f "$EXE" ]; then printf travis_fold":start:crashlog\n\033[31;1m%s\033[0m\n" "$CORE"; gdb --batch -q -c "$CORE" "$EXE" -iex 'set auto-load off' -iex 'dir src/' -iex 'set sysroot .' -ex bt -ex q; echo travis_fold":"end:crashlog; fi; done || true
travis_fold:end:after_failure.4
travis_fold:start:after_failure.5
travis_time:start:03b7f4aa
$ cat ./obj/build/x86_64-unkn

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 @TimNN. (Feature Requests)

[oli-obk]

@bors try

[bors]

⌛ Trying commit 3b4a86558fd9c1a61498a7aab208b37a18d8cfa2 with merge 311b39b143bf0b5cdfcb183aaeb0356b5eb29ae7...

[oli-obk]

@rust-timer build 311b39b143bf0b5cdfcb183aaeb0356b5eb29ae7

this might regress max-rss

[rust-timer]

Success: Queued 311b39b143bf0b5cdfcb183aaeb0356b5eb29ae7 with parent a5dfdc5, comparison URL.

[bors]

☀️ Try build successful - checks-travis
Build commit: 311b39b143bf0b5cdfcb183aaeb0356b5eb29ae7

[rust-timer]

Finished benchmarking try commit 311b39b143bf0b5cdfcb183aaeb0356b5eb29ae7

[oli-obk]

Seems like max-rss regresses in some situations but is improved in others?

https://perf.rust-lang.org/compare.html?start=a5dfdc589a1b44f01cb640cd0244372dcbbd6f37&end=311b39b143bf0b5cdfcb183aaeb0356b5eb29ae7&stat=max-rss

Not sure how reliable some of those numbers are.

[oli-obk]

rebasing and fixing build now

[oli-obk]

@bors r=eddyb

[bors]

📌 Commit 0b732aa has been approved by eddyb

[bors]

⌛ Testing commit 0b732aa with merge f492693...

[bors]

☀️ Test successful - checks-travis, status-appveyor
Approved by: eddyb
Pushing f492693 to master...