Add #[doc(hidden)] attribute on compiler generated module.

[iliekturtles]

Resolves unavoidable missing_docs warning/error on proc-macro crates.
Resolves#42008.

Changes not yet tested locally, however I wanted to submit first since rustc takes forever to compile.

[rust-highfive]

r? @alexcrichton

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[alexcrichton]

Thanks! I think that one of the arguments to item_mod is the list of attributes, so perhaps this could be included in there? Additionally could a test be added for this?

[iliekturtles]

I see where the code changes can be made (also noticed mk_decls has a comment that should be updated). Where do tests for this method live?

[alexcrichton]

Tests typically live in src/test, and there's a number of locations a test could be added but my guess is that src/test/ui may be the most appropriate for this test.

[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:32136ab9:start=1557190013426422078,finish=1557190014194054855,duration=767632777
$ 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
$ export AWS_ACCESS_KEY_ID=AKIA46X5W6CZEJZ6XT55
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---
[01:14:00] ---- [ui] ui/proc-macro/no-missing-docs.rs stdout ----
[01:14:00] [01:14:00] error: ui test compiled successfully!
[01:14:00] status: exit code: 0
[01:14:00] command: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage2/bin/rustc" "/checkout/src/test/ui/proc-macro/no-missing-docs.rs" "-Zthreads=1" "--target=x86_64-unknown-linux-gnu" "--error-format" "json" "-Zui-testing" "-o" "/checkout/obj/build/x86_64-unknown-linux-gnu/test/ui/proc-macro/no-missing-docs/a" "-Crpath" "-O" "-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/proc-macro/no-missing-docs/auxiliary" "-A" "unused"
[01:14:00] ------------------------------------------
[01:14:00] [01:14:00] ------------------------------------------
[01:14:00] stderr:
---
[01:14:00] thread 'main' panicked at 'Some tests failed', src/tools/compiletest/src/main.rs:519:22
[01:14:00] note: Run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
[01:14:00] [01:14:00] [01:14:00] 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" "/usr/lib/llvm-6.0/bin/FileCheck" "--host-rustcflags" "-Crpath -O -Zunstable-options -Lnative=/checkout/obj/build/x86_64-unknown-linux-gnu/native/rust-test-helpers" "--target-rustcflags" "-Crpath -O -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" "--quiet" "--llvm-version" "6.0.0\n" "--system-llvm" "--cc" "" "--cxx" "" "--cflags" "" "--llvm-components" "" "--llvm-cxxflags" "" "--adb-path" "adb" "--adb-test-dir" "/data/tmp/work" "--android-cross-path" "" "--color" "always"
[01:14:00] [01:14:00] [01:14:00] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test
[01:14:00] Build completed unsuccessfully in 0:04:31
[01:14:00] Build completed unsuccessfully in 0:04:31
[01:14:00] make: *** [check] Error 1
[01:14:00] Makefile:48: recipe for target 'check' failed
The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
travis_time:start:157fafb4
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)
Tue May 7 02:01:06 UTC 2019
---
travis_time:end:004554aa:start=1557194467539389480,finish=1557194467548611035,duration=9221555
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:03f8e2fe
$ 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:088f680f
travis_time:start:088f680f
$ 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:1394c9ca
$ 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)

[alexcrichton]

I think you may need to also tag the test with // compile-pass to avoid trying to execute it?

[iliekturtles]

Ahhh thanks! I only had time to write the test but not run it locally last time. Will make that adjustment in the next few days and push the changes when I believe we're ready for a final review.

[iliekturtles]

@alexcrichton, I believe everything is set for your review. Tests are passing locally.

[alexcrichton]

@bors: r+
Thanks!

[bors]

📌 Commit 5ccf2fb has been approved by alexcrichton

[bors]

🌲 The tree is currently closed for pull requests below priority 500, this pull request will be tested once the tree is reopened