Remove LLVM 3.9 workaround.

[irinagpopa]

No description provided.

[rust-highfive]

r? @davidtwco

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[davidtwco]

r? @nikomatsakis

[cuviper]

Here's a little context on the null, since I was just investigating this for someone debugging Rust 1.28 with LLVM 3.9. Their problem was that the other call to LLVMRustDIBuilderCreateStaticVariable does sometimes use ptr::null() for the linkage name. (i.e. It didn't have this workaround.)

We pass that pointer to createGlobalVariableExpression(..., StringRef LinkageName, ...), and StringRef didn't accept null pointers until D24904, which went into LLVM 4.0. With LLVM 3.9, a null pointer will get passed to strlen, which is UB.

[tromey]

FWIW this looks good to me.

[nikomatsakis]

@bors r=tromey

[bors]

📌 Commit 40e7667 has been approved by tromey

[nikomatsakis]

@bors r-

[nikomatsakis]

@bors r=tromey

[bors]

📌 Commit 40e7667 has been approved by tromey

[bors]

⌛ Testing commit 40e7667 with merge 81298a7165c77599b239605ffe9f85b4c2d9bee2...

[bors]

💔 Test failed - status-travis

[rust-highfive]

The job dist-mips64el-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.

travis_time:end:00ab9b66:start=1537425179212859245,finish=1537425179217621979,duration=4762734
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:1055f1a2
$ 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 -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:0e4f79ce
travis_time:start:0e4f79ce
$ 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:01e4343c
$ 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