rustc: Handle linker diagnostics from LLVM

[alexcrichton]

Previously linker diagnostic were being hidden when two modules were linked
together but failed to link. This commit fixes the situation by ensuring that we
have a diagnostic handler installed and also adds support for handling linker
diagnostics.

[rust-highfive]

r? @eddyb

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[eddyb]

Can this wait (a couple days) for #52461? I'd rather nothing change in rustc_codegen_llvm until that is merged because small changes getting into a rebase that scale could introduce unsoundness.

[alexcrichton]

Sure thing!

[kennytm]

#52461 has been merged, unblocking.

[alexcrichton]

Thanks for the ping @kennytm, should be updated now.

re-r? @eddyb

[eddyb]

@bors r+

[bors]

📌 Commit f0bceba has been approved by eddyb

[bors]

⌛ Testing commit f0bceba with merge f4de37b...

[bors]

💔 Test failed - status-travis

[rust-highfive]

The job x86_64-gnu-aux 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.

[01:36:37] [TIMING] ToolBuild { compiler: Compiler { stage: 0, host: "x86_64-unknown-linux-gnu" }, target: "x86_64-unknown-linux-gnu", tool: "cargotest", path: "src/tools/cargotest", mode: ToolBootstrap, is_optional_tool: false, source_type: InTree, extra_features: [] } -- 1.421
[01:36:37] testing https://github.com/servo/webrender
[01:36:37] Initialized empty Git repository in /checkout/obj/build/ct/webrender/.git/
[01:36:37] fatal: Could not parse object '57250b2b8fa63934f80e5376a29f7dcb3f759ad6'.
[01:37:33] fatal: unable to access 'https://github.com/servo/webrender/': Could not resolve host: github.com
[01:37:33] thread 'main' panicked at 'assertion failed: status.success()', tools/cargotest/main.rs:128:13
[01:37:33] 
[01:37:33] 
[01:37:33] command did not execute successfully: "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0-tools-bin/cargotest" "/checkout/obj/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "/checkout/obj/build/ct"
[01:37:33] expected success, got: exit code: 101
[01:37:33] expected success, got: exit code: 101
[01:37:33] 
[01:37:33] 
[01:37:33] failed to run: /checkout/obj/build/bootstrap/debug/bootstrap test src/test/pretty src/test/run-pass/pretty src/test/run-fail/pretty src/test/run-pass-valgrind/pretty src/test/run-pass-fulldeps/pretty src/test/run-fail-fulldeps/pretty src/tools/cargo src/tools/cargotest
[01:37:33] Build completed unsuccessfully in 0:34:54
[01:37:33] make: *** [check-aux] Error 1
[01:37:33] Makefile:60: recipe for target 'check-aux' failed

The command "stamp sh -x -c "$RUN_SCRIPT"" exited with 2.
travis_time:start:287733f0
$ date && (curl -fs --head https://google.com | grep ^Date: | sed 's/Date: //g' || true)
---
travis_time:end:3d22c29c:start=1533105732399760091,finish=1533105732405382182,duration=5622091
travis_fold:end:after_failure.3
travis_fold:start:after_failure.4
travis_time:start:10df0bf0
$ 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:14e19370
travis_time:start:14e19370
$ 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:2cc61d5e
$ 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

[bors]

⌛ Testing commit f0bceba with merge 11f812a...

[bors]

☀️ Test successful - status-appveyor, status-travis
Approved by: eddyb
Pushing 11f812a to master...