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cargo_rustc: remove workaround for fixed upstream issue #4581

Merged
merged 1 commit into from
Oct 10, 2017
Merged

cargo_rustc: remove workaround for fixed upstream issue #4581

merged 1 commit into from
Oct 10, 2017

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tamird
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@tamird tamird commented Oct 5, 2017

Fixed in rust-lang/rust#25411. Also, the
removed code is implicated in test failures observed in
rust-lang/rust#44515.

r? @alexcrichton

tamird referenced this pull request Oct 5, 2017
This commit is an architectural change inside of Cargo itself in the way that it
handles the output format of builds. Previously when a build start, all existing
directories and files would be renamed to `old-foo` folders. The build would
then `rename` all files back into the right location as they were seen as fresh
and needed for the build.

The benefit of a system such as this is a rock-solid guarantee that the build
tree contains exactly what it would if we were to start the build from a totally
clean directory each time. There are some downsides, however:

* In #800, it was discovered that this method has an unfortunate interaction
  with Docker. Docker apparently will mount many filesystems which `rename` will
  not work across.

* I have seen countless flaky failures on windows due to an attempt to remove a
  file that was still in use somehow. I've never been able to truly track down
  why these failures are happening, however.

The new system for managing output files is to build up a list of all known
files at the start of a build, whitelist any necessary files when the build is
being prepared, and then wipe out all unknown files right before the build
begins. This is not quite as close to the guarantee as the benefits reaped
before because on the second build all build files will still be in their final
output locations, they may just get updated as part of the build as well. This
seems like an acceptable compromise, however.

Closes #800
@alexcrichton
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While I think it's worth considering removing this block, I'm pretty certain it won't fix rust-lang/rust#44515 because this code path shouldn't get hit during testing, the compiler-bulitins crate should be fresh and avoid hitting rustc at all

@tamird
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tamird commented Oct 7, 2017

OK - now that rust-lang/rust#44515 is merged, this can be evaluated on its own.

@alexcrichton
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The comment in the middle I think is why this can't be removed. That was added after the first comment was originally added.

@tamird
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tamird commented Oct 10, 2017

@alexcrichton updated to keep the part added in 4b82fdc.

Fixed in rust-lang/rust#25411. Also, the
removed code is implicated in test failures observed in
rust-lang/rust#44515.
@alexcrichton
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@bors: r+

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bors commented Oct 10, 2017

📌 Commit 8b68e59 has been approved by alexcrichton

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bors commented Oct 10, 2017

⌛ Testing commit 8b68e59 with merge d6843a7...

bors added a commit that referenced this pull request Oct 10, 2017
cargo_rustc: remove workaround for fixed upstream issue

Fixed in rust-lang/rust#25411. Also, the
removed code is implicated in test failures observed in
rust-lang/rust#44515.

r? @alexcrichton
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bors commented Oct 10, 2017

☀️ Test successful - status-appveyor, status-travis
Approved by: alexcrichton
Pushing d6843a7 to master...

@bors bors merged commit 8b68e59 into rust-lang:master Oct 10, 2017
@ehuss ehuss added this to the 1.22.0 milestone Feb 6, 2022
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4 participants