Fix #23808: dead_code lint: visit types in paths

[TimNN]

Fixes #23808, passes make check-stage1 run-pass and run-fail locally.

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[TimNN]

So, I had a look at the travis logs and it looks like the pretty test failed because pretty forces a crate_type="lib", thus the main function is not called and the #![deny(dead_code)] triggers.

What would be the best solution to fix this? Disable the test for pretty? How do I do that?

[TimNN]

Ok, so I think I fixed the issue by making main pub, make check-stage1-pretty NO_REBUILD=1 TESTNAME=issue-23808 now also passes locally.

[nrc]

It would be nice if we didn't need pub main - that was a requirement for a while that was lifted and life has been much easier. Do you know why pretty makes the crate type lib?

[TimNN]

I have no clue, this is the first time I have worked on the rust compiler. The only other alternative I can think of is to disable pretty for this test. Or is it possible to use #![crate_type="bin"] to overwrite a --crate-type=lib?

[TimNN]

Alright, I removed the pub again, this now has to wait for #27567

[TimNN]

Alright, now that #27571 is merged this should build. I just rebased & pushed again to get travis to test it again.

[TimNN]

Alright, this doesn't compile at the moment due to some recent rust changes, I'll fix this now.

[TimNN]

Please don't r+ yet, I need to add another test case which came up on reddit:
https://www.reddit.com/r/rust/comments/3gmtpq/why_do_i_get_a_struct_never_used_here/

[TimNN]

Alright, I added the new test cases. They would probably not have been necessary, but I wanted to be on the safe side.

[TimNN]

@nrc: could you review again?

[nrc]

@bors: r+

@TimNN looks good, thanks for seeing through the changes

[bors]

📌 Commit 2d4e07e has been approved by nrc

[bors]

⌛ Testing commit 2d4e07e with merge 3c35d55...

[bors]

💔 Test failed - auto-mac-32-opt

[TimNN]

@nrc could you retry? this passes make check locally (on linux) and I don't think there is any target dependent code in that part of the compiler.

[alexcrichton]

That doesn't look like it's spurious (may be #27583), but I don't think a retry will fix it. Can you reproduce locally? Perhaps on a 32-bit build?

[TimNN]

@alexcrichton I'm trying a local 32bit build now but I can't imagine how my changed could cause a test failure there, except if they just expose another bug.

If this turns out to be #27583, how would I go about fixing this? Just wait until the issue is fixed or add one of the workarounds from the issue to ExprUseVisitor::new()?

[alexcrichton]

Unfortunately I'm not sure if there's a fix, but #27856 is also block on this and @nikomatsakis indicates that #27892 may fix it.

[TimNN]

Thanks for the additional links! I'll see if the local build will result in anything and wait for #27892 otherwise. I never imagined that this rather small pull request would cause so much trouble, even if it did take some (rather enjoyable) hours to figuring this fix out.

[TimNN]

Alright, so the local 32bit linux build failed as well, so I'll wait on #27892 and then try again

[TimNN]

Since #27892 has landed now, could someone retry please?

[alexcrichton]

@bors: retry

[bors]

⌛ Testing commit 2d4e07e with merge 4a1fda8...

[bors]

☀️ Test successful - auto-linux-32-nopt-t, auto-linux-32-opt, auto-linux-64-nopt-t, auto-linux-64-opt, auto-linux-64-x-android-t, auto-mac-32-opt, auto-mac-64-nopt-t, auto-mac-64-opt, auto-win-gnu-32-nopt-t, auto-win-gnu-32-opt, auto-win-gnu-64-nopt-t, auto-win-gnu-64-opt, auto-win-msvc-32-opt, auto-win-msvc-64-opt