Rollup of 6 pull requests

[Centril]

Successful merges:

• Remove as_str if the type is already &str #64739 (Remove as_str if the type is already &str)
• Note when a mutable trait object is needed #65077 (Note when a mutable trait object is needed)
• Correctly estimate the required space for string in StyledBuffer::prepend #65120 (Correctly estimate the required space for string in StyledBuffer::prepend)
• Suggest dereferencing boolean reference when used in 'if' or 'while' #65150 (Suggest dereferencing boolean reference when used in 'if' or 'while')
• Add long error explanation for E0566 #65164 (Add long error explanation for E0566)
• Update reference #65173 (Update reference)

Failed merges:

r? @ghost

[Centril]

@bors r+ p=6 rollup=never

[bors]

📌 Commit ca3f01a has been approved by Centril

[bors]

⌛ Testing commit ca3f01a with merge f776b9a45ae147c060023936637c4309644b46bb...

[bors]

💔 Test failed - checks-azure

[rust-highfive]

The job x86_64-gnu 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.

2019-10-07T05:33:36.1694113Z failures:
2019-10-07T05:33:36.1694192Z 
2019-10-07T05:33:36.1694657Z ---- [ui] ui/where-clauses/where-for-self-2.rs stdout ----
2019-10-07T05:33:36.1694734Z 
2019-10-07T05:33:36.1694809Z error: Error: expected failure status (Some(1)) but received status Some(101).
2019-10-07T05:33:36.1694910Z status: exit code: 101
2019-10-07T05:33:36.1696016Z command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/ui/where-clauses/where-for-self-2.rs" "-Zthreads=1" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "-Zui-testing" "-C" "prefer-dynamic" "--out-dir" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/where-clauses/where-for-self-2" "-Crpath" "-O" "-Cdebuginfo=0" "-Zunstable-options" "-Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "-L" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/where-clauses/where-for-self-2/auxiliary" "-A" "unused"
2019-10-07T05:33:36.1697543Z ------------------------------------------
2019-10-07T05:33:36.1697600Z 
2019-10-07T05:33:36.1697867Z ------------------------------------------
2019-10-07T05:33:36.1697944Z stderr:
2019-10-07T05:33:36.1697944Z stderr:
2019-10-07T05:33:36.1698248Z ------------------------------------------
2019-10-07T05:33:36.1698606Z thread 'rustc' panicked at 'assertion failed: !value.has_escaping_bound_vars()', src/librustc/ty/sty.rs:896:9
2019-10-07T05:33:36.1698944Z 
2019-10-07T05:33:36.1699016Z error: internal compiler error: unexpected panic
2019-10-07T05:33:36.1699082Z 
2019-10-07T05:33:36.1699155Z note: the compiler unexpectedly panicked. this is a bug.
2019-10-07T05:33:36.1699155Z note: the compiler unexpectedly panicked. this is a bug.
2019-10-07T05:33:36.1699206Z 
2019-10-07T05:33:36.1699580Z note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports
2019-10-07T05:33:36.1699670Z 
2019-10-07T05:33:36.1699956Z note: rustc 1.40.0-dev running on x86_64-unknown-linux-gnu
2019-10-07T05:33:36.1700014Z 
2019-10-07T05:33:36.1700350Z note: compiler flags: -Z threads=1 -Z ui-testing -Z unstable-options -C prefer-dynamic -C rpath -C debuginfo=0
2019-10-07T05:33:36.1700459Z 
2019-10-07T05:33:36.1700712Z ------------------------------------------
2019-10-07T05:33:36.1700765Z 
2019-10-07T05:33:36.1700818Z 
---
2019-10-07T05:33:36.1701949Z thread 'main' panicked at 'Some tests failed', src/tools/compiletest/src/main.rs:537:22
2019-10-07T05:33:36.1702057Z note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
2019-10-07T05:33:36.1702142Z 
2019-10-07T05:33:36.1702177Z 
2019-10-07T05:33:36.1704115Z command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/compiletest" "--compile-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib" "--run-lib-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/x86_64-unknown-linux-gnu/lib" "--rustc-path" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "--src-base" "/checkout/src/test/ui" "--build-base" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui" "--stage-id" "stage2-x86_64-unknown-linux-gnu" "--mode" "ui" "--target" "x86_64-unknown-linux-gnu" "--host" "x86_64-unknown-linux-gnu" "--llvm-filecheck" "/checkout/obj/build/x86_64-unknown-linux-gnu/llvm/build/bin/FileCheck" "--host-rustcflags" "-Crpath -O -Cdebuginfo=0 -Zunstable-options  -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--target-rustcflags" "-Crpath -O -Cdebuginfo=0 -Zunstable-options  -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--docck-python" "/usr/bin/python2.7" "--lldb-python" "/usr/bin/python2.7" "--gdb" "/usr/bin/gdb" "--llvm-version" "9.0.0-rust-1.40.0-dev\n" "--cc" "" "--cxx" "" "--cflags" "" "--llvm-components" "" "--llvm-cxxflags" "" "--adb-path" "adb" "--adb-test-dir" "/data/tmp/work" "--android-cross-path" "" "--color" "always"
2019-10-07T05:33:36.1704816Z 
2019-10-07T05:33:36.1704854Z 
2019-10-07T05:33:36.1704952Z failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
2019-10-07T05:33:36.1705040Z Build completed unsuccessfully in 1:37:42
2019-10-07T05:33:36.1705040Z Build completed unsuccessfully in 1:37:42
2019-10-07T05:33:36.1705134Z == clock drift check ==
2019-10-07T05:33:36.1705207Z   local time: Mon Oct  7 05:33:35 UTC 2019
2019-10-07T05:33:36.1705365Z   network time: Mon, 07 Oct 2019 05:33:35 GMT
2019-10-07T05:33:36.1705440Z == end clock drift check ==
2019-10-07T05:33:37.2179742Z ##[error]Bash exited with code '1'.
2019-10-07T05:33:37.2220971Z ##[section]Starting: Upload CPU usage statistics
2019-10-07T05:33:37.2233301Z ==============================================================================
2019-10-07T05:33:37.2233381Z Task         : Bash
2019-10-07T05:33:37.2233459Z Description  : Run a Bash script on macOS, Linux, or Windows

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)

[Centril]

I have no idea which PR is to blame... cc @estebank @tmandry

[estebank]

@Centril it might be mine.