commit 3350edf8fdcab10b60bf8173bd3b1551f567cd44
author Nicholas Nethercote <n.nethercote@gmail.com> Thu Oct 31 11:02:22 2024 +1100
committer Nicholas Nethercote <n.nethercote@gmail.com> Tue Nov 05 10:18:01 2024 +1100
tree f188a59ceb22e9ef045f6fb42680dfcd9744e2d9
parent fbab78289dd8c6e8860034e0048cfb538f217700

Replace `BorrowckResults` with `Borrowck`.

The results of most analyses end up in a `Results<'tcx, A>`, where `A`
is the analysis. It's then possible to traverse the results via a
`ResultsVisitor`, which relies on the `ResultsVisitable` trait. (That
trait ends up using the same `apply_*` methods that were used when
computing the analysis, albeit indirectly.)

This pattern of "compute analysis results, then visit them" is common.
But there is one exception. For borrow checking we compute three
separate analyses (`Borrows`, `MaybeUninitializedPlaces`, and
`EverInitializedPlaces`), combine them into a single `BorrowckResults`,
and then do a single visit of that `BorrowckResults` with
`MirBorrowckResults`. `BorrowckResults` is just different enough from
`Results` that it requires the existence of `ResultsVisitable`, which
abstracts over the traversal differences between `Results` and
`BorrowckResults`.

This commit changes things by introducing `Borrowck` and bundling the
three borrowck analysis results into a standard `Results<Borrowck>`
instead of the exceptional `BorrowckResults`. Once that's done, the
results can be visited like any other analysis results.
`BorrowckResults` is removed, as is `impl ResultsVisitable for
BorrowckResults`. (It's instructive to see how similar the added `impl
Analysis for Borrowck` is to the removed `impl ResultsVisitable for
BorrowckResults`. They're both doing exactly the same things.)

Overall this increases the number of lines of code and might not seem
like a win. But it enables the removal of `ResultsVisitable` in the next
commit, which results in many simplifications.