Only run dataflow for const qualification if type-based check would fail #71330
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r? @varkor (rust_highfive has picked a reviewer for you, use r? to override) |
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r? @oli-obk |
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| // We can use `unsound_ignore_borrow_on_drop` here because custom drop impls are not | ||
| // allowed in a const. | ||
| // | ||
| // FIXME(ecstaticmorse): Someday we want to allow custom drop impls. How do we do this |
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we can lower Drop terminators for types that have a const Drop bound to a function call before doing this analysis.
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So... hypothetically we could now have a situation where const checking does not cause a cycle error anymore, optimizations eliminate the cycle error and then const eval (which runs on optimized MIR) does not cause a cycle error? |
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That's correct. I think the solution is to explicitly trigger |
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Sidebar: what do you think about renaming a few modules/types in |
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☔ The latest upstream changes (presumably #71044) made this pull request unmergeable. Please resolve the merge conflicts. |
I have a branch for that that I'm rebasing since yesterday |
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So yea, I'm in favour of liberally renaming modules and types to match our terminology better or just be more consistent |
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r=me on this PR after a rebase |
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☔ The latest upstream changes (presumably #71467) made this pull request unmergeable. Please resolve the merge conflicts. |
This was needed by an early version of dataflow-based const qualification where `QualifCursor` needed to return a full `BitSet` with the current state.
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@bors r=oli-obk |
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📌 Commit 15f95b1 has been approved by |
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…=oli-obk Only run dataflow for const qualification if type-based check would fail This is the optimization discussed in rust-lang#49146 (comment). We wait for `Qualif::in_any_value_of_ty` to return `true` before running dataflow. For bodies that deal mostly with primitive types, this will avoid running dataflow at all during const qualification. This also removes the `BitSet` used to cache `in_any_value_of_ty` for each local, which was only necessary for an old version of rust-lang#64470 that also handled promotability.
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Rollup of 8 pull requests Successful merges: - rust-lang#69456 (fix misleading type annotation diagonstics) - rust-lang#71330 (Only run dataflow for const qualification if type-based check would fail) - rust-lang#71480 (Improve PanicInfo examples readability) - rust-lang#71485 (Add BinaryHeap::retain as suggested in rust-lang#42849) - rust-lang#71512 (Remove useless "" args) - rust-lang#71527 (Miscellaneous cleanup in `check_consts`) - rust-lang#71534 (Avoid unused Option::map results) - rust-lang#71535 (Fix typos in docs for keyword "in") Failed merges: r? @ghost
I'd be happy to see that happen. :D |
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This is the optimization discussed in #49146 (comment). We wait for
Qualif::in_any_value_of_tyto returntruebefore running dataflow. For bodies that deal mostly with primitive types, this will avoid running dataflow at all during const qualification.This also removes the
BitSetused to cachein_any_value_of_tyfor each local, which was only necessary for an old version of #64470 that also handled promotability.