Utilize ? instead of return None.

[frewsxcv]

No description provided.

[rust-highfive]

r? @cramertj

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[varkor]

@bors r+ rollup

[bors]

📌 Commit a14aa3d6d75609957f047ce5714136385060a76e has been approved by varkor

[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:14c381a0:start=1553552382442023990,finish=1553552383338734284,duration=896710294
$ 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
---
[00:06:21]    Compiling rustc_errors v0.0.0 (/checkout/src/librustc_errors)
[00:06:45]    Compiling synstructure v0.10.1
[00:07:04]    Compiling rustc_macros v0.1.0 (/checkout/src/librustc_macros)
[00:07:51]    Compiling syntax_ext v0.0.0 (/checkout/src/libsyntax_ext)
[00:07:51] error: expected one of `.`, `?`, `{`, or an operator, found `;`
[00:07:51]    --> src/librustc/traits/util.rs:295:45
[00:07:51]     |
[00:07:51] 295 |         let def_id = match self.stack.pop()?;
[00:07:51]     |                      -----                  ^ expected one of `.`, `?`, `{`, or an operator here
[00:07:51]     |                      while parsing this match expression
[00:07:51]     |                      help: try removing this `match`
[00:07:51] 
[00:08:24] error: aborting due to previous error
---
198068 ./obj/build/cache/2019-02-27
157396 ./obj/build/bootstrap/debug/incremental
156416 ./src/llvm-project/clang
142512 ./obj/build/bootstrap/debug/incremental/bootstrap-pz4opbgkzvy
142508 ./obj/build/bootstrap/debug/incremental/bootstrap-pz4opbgkzvy/s-faos6w1wbn-1gdqdwt-3u618d595ya6l
108532 ./src/llvm-project/lldb
103952 ./obj/build/x86_64-unknown-linux-gnu/stage0-rustc
97584 ./src/llvm-project/clang/test
94360 ./.git
---
ls: cannot travis_time:end:0290c126:start=1553552899831616293,finish=1553552899839003586,duration=7387293
travis_fold:end:after_failure.4
travis_fold:start:after_failure.5
travis_time:start:0f3190ce
$ 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:2720cd9c
$ 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)

[frewsxcv]

@bors r=varkor

removed the match

[bors]

📌 Commit 28c602a has been approved by varkor