typeck: simplify the handling of diverges
#68422
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| let scrut_diverges = self.diverges.get(); | ||
| self.diverges.set(Diverges::Maybe); | ||
| // Otherwise, we have to union together the types that the arms produce and so forth. | ||
| let scrut_diverges = self.diverges.replace(Diverges::Maybe); |
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Ohh, we might have more similar places where we use get and set, predating Cell::replace.
I found some in these two files, if someone wants to take them:
src/librustc/ty/print/pretty.rssrc/librustc/infer/mod.rs
(there's others, but they use the result of get() to compute the value to set, and I don't think we have a nice abstraction for that)
| // #55810: Type check patterns first so we get types for all bindings. | ||
| for arm in arms { | ||
| self.check_pat_top(&arm.pat, scrut_ty, Some(scrut.span), true); | ||
| } |
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I assume "they're now subsumed by unreachable_patterns warnings" in the deleted comment is why you can do this change now?
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Filed #68429.
(To recap what I said in private: check/pat.rs does not mention diverges, except indirectly by type checking expressions, which only occur in literals and range patterns, but those cannot be typed at a diverging type, so removing this code has no effect.)
| @@ -200,16 +183,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { | |||
| arms: &'tcx [hir::Arm<'tcx>], | |||
| source: hir::MatchSource, | |||
| ) { | |||
| if self.diverges.get().is_always() { | |||
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I think this was a performance microopt?
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@bors r+ |
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📌 Commit 7dceff9 has been approved by |
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typeck: simplify the handling of `diverges` Some drive-by cleanup while working on `hir::ExprKind::Let`. Ostensibly, this has some perf benefits due to reduced allocation and whatnot as well. r? @eddyb
typeck: simplify the handling of `diverges` Some drive-by cleanup while working on `hir::ExprKind::Let`. Ostensibly, this has some perf benefits due to reduced allocation and whatnot as well. r? @eddyb
Some drive-by cleanup while working on
hir::ExprKind::Let.Ostensibly, this has some perf benefits due to reduced allocation and whatnot as well.
r? @eddyb