Point at end of macro arm when encountering EOF

[estebank]

Fix #52866.

[rust-highfive]

r? @nikomatsakis

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[estebank]

@nikomatsakis Some of this is very hacky, but I feel that the results are really worth it (and difficult to accomplish in a cleaner way without a large refactor).

These are the representative output to look at:

https://github.com/rust-lang/rust/pull/55402/files#diff-453bf49f4eab03f41a4f7a20c084b3c5
https://github.com/rust-lang/rust/pull/55402/files#diff-cd2612a6b8b62c5dbf63078873af0ffc
https://github.com/rust-lang/rust/pull/55402/files#diff-e92d884451d7aba4a234400faed2cff5
https://github.com/rust-lang/rust/pull/55402/files#diff-1d3cccb183f9a24871ea6f0d4321788b

I refrained from further complicating the code to handle the last one with a custom diagnostic because I feel that it is enough of an improvement as it is. (If you disagree, it can certainly be expanded.)

[nikomatsakis]

Seems good. The results are indeed good. I still feel like the message can get better but I'm not sure that what I proposed is an improvement exactly. Thoughts?

[nikomatsakis]

@bors r+

[bors]

📌 Commit d011313 has been approved by nikomatsakis

[bors]

⌛ Testing commit d011313 with merge f52204ce1b664dcc16ada1ee65284c4cde7b24ba...

[bors]

💔 Test failed - status-travis

[rust-highfive]

The job dist-armv7-linux 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.

Building stage2 tool cargo (armv7-unknown-linux-gnueabihf)
[01:10:47]  Downloading crates ...
[01:11:07] warning: spurious network error (2 tries remaining): [6] Couldn't resolve host name (Could not resolve host: crates.io)
[01:11:27] warning: spurious network error (1 tries remaining): [6] Couldn't resolve host name (Could not resolve host: crates.io)
[01:11:47] error: failed to download from `https://crates.io/api/v1/crates/openssl-src/111.0.1+1.1.1/download`
[01:11:47] Caused by:
[01:11:47]   [6] Couldn't resolve host name (Could not resolve host: crates.io)
[01:11:47] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "build" "--target" "armv7-unknown-linux-gnueabihf" "-j" "4" "--release" "--locked" "--color" "always" "--manifest-path" "/checkout/src/tools/cargo/Cargo.toml" "--features" "rustc-workspace-hack/all-static" "--message-format" "json"
[01:11:47] expected success, got: exit code: 101
---
travis_time:end:0168e56e:start=1543300439091560957,finish=1543300439101956914,duration=10395957
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:01f722e5
$ 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:0ef126a6
travis_time:start:0ef126a6
$ cat ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers || true
cat: ./obj/build/x86_64-unknown-linux-gnu/native/asan/build/lib/asan/clang_rt.asan-dynamic-i386.vers: No such file or directory
travis_fold:end:after_failure.5
travis_fold:start:after_failure.6
travis_time:start:02d6fc2e
$ dmesg | grep -i kill

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)

[kennytm]

@bors retry travis-ci/travis-ci#9696

[kennytm]

@bors p=29

rollup fairness

[bors]

⌛ Testing commit d011313 with merge 10e2c72...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: nikomatsakis
Pushing 10e2c72 to master...