NLL: change compare-mode=nll to use borrowck=migrate #55118
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A-NLL
Area: Non-lexical lifetimes (NLL)
NLL-complete
Working towards the "valid code works" goal
NLL-diagnostics
Working towards the "diagnostic parity" goal
NLL-sound
Working towards the "invalid code does not compile" goal
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(The reason I hadn't proposed this earlier is that I had hoped that I would "simply" resolve issue #52979. But that turned out to be quite difficult in practice.) |
pnkfelix
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tagging with multiple NLL-labels because this kind of task overlaps all these buckets |
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Oct 17, 2018
NLL: change compare-mode=nll to use borrowck=migrate Fixes #55118. This PR is split into two parts: The first commit is a minor change that fixes a flaw in the existing `borrowck=migrate` implementation whereby a lint that was promoted to an error in the AST borrow checker would result in the same lint from the NLL borrow checker being downgraded to a warning in migrate mode. This PR fixes this by ensuring lints are exempt from buffering in the NLL borrow checker. The second commit updates `compiletest` to make the NLL compare mode use `-Z borrowck=migrate` rather than `-Z borrowck=mir`. The third commit shows all the test output changes that result from this. r? @pnkfelix
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Oct 17, 2018
NLL: change compare-mode=nll to use borrowck=migrate Fixes #55118. This PR is split into two parts: The first commit is a minor change that fixes a flaw in the existing `borrowck=migrate` implementation whereby a lint that was promoted to an error in the AST borrow checker would result in the same lint from the NLL borrow checker being downgraded to a warning in migrate mode. This PR fixes this by ensuring lints are exempt from buffering in the NLL borrow checker. The second commit updates `compiletest` to make the NLL compare mode use `-Z borrowck=migrate` rather than `-Z borrowck=mir`. The third commit shows all the test output changes that result from this. r? @pnkfelix
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We have a couple different modes that NLL can run in.
borrowck=mir is sort of the "adopt NLL whole hog"; it just runs the MIR-based borrow checker, and reports its errors as, well, errors.
borrowck=migrate is the migration plan for the 2018 edition. It runs the MIR-based borrow checker, and if it signals an error, then it runs the old AST-based borrow checker as a backup. If the code is accepted by AST-based borrow checker, then all the MIR-based errors are downgraded to warnings. This is the mode that we'll be deploying for Rust 2018.
Anyway: We are currently testing borrowck=mir for our test suite via
compare-mode=nll.The plan is to deploy borrowck=migrate.
We have barely any automated testing of borrowck=migrate.
See the problem here?
My proposal: We should change
compare-mode=nllto useborrowck=migrateinstead ofborrowck=mir. We should make this change ASAP.The text was updated successfully, but these errors were encountered: