match lowering: simplify block creation #120978
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…iaskrgr Rollup of 8 pull requests Successful merges: - rust-lang#114877 (unstable-book: add quick-edit link) - rust-lang#120548 (rustdoc: Fix handling of doc_auto_cfg feature for cfg attributes on glob reexport) - rust-lang#120549 (modify alias-relate to also normalize ambiguous opaques) - rust-lang#120959 (Remove good path delayed bugs) - rust-lang#120978 (match lowering: simplify block creation) - rust-lang#121019 (coverage: Simplify some parts of the coverage span refiner) - rust-lang#121021 (Extend intra-doc link chapter in the rustdoc book) - rust-lang#121031 (RustWrapper: adapt for coverage mapping API changes) Failed merges: - rust-lang#121014 (Remove `force_print_diagnostic`) r? `@ghost` `@rustbot` modify labels: rollup
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Rollup merge of rust-lang#120978 - Nadrieril:sane-blocks, r=matthewjasper match lowering: simplify block creation Match lowering was doing complicated things with block creation. As far as I can tell it was trying to avoid creating unneeded blocks, but of the three places that start out with `otherwise = &mut None`, two of them called `otherwise.unwrap_or_else(|| self.cfg.start_new_block())` anyway. As far as I can tell the only place where this PR makes a difference is in `lower_match_tree`, which did indeed sometimes avoid creating the unreachable final block + FakeRead. Unless this is important I propose we do the naive thing instead. I have not checked all the graph isomorphisms by hand, but at a glance the test diff looks sensible. r? `@matthewjasper`
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This comment was historically inside a block guarded by `if let Some(otherwise_block) = otherwise`. When rust-lang#120978 made the otherwise block non-optional, it also flattened that region of code. Doing so left this comment awkwardly stranded aboven an unrelated line of code, without its original context. We can restore that context by moving it above the declaration of `otherwise`.
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This comment was historically inside a block guarded by `if let Some(otherwise_block) = otherwise`. When rust-lang#120978 made the otherwise block non-optional, it also flattened that region of code. Doing so left this comment awkwardly stranded above an unrelated line of code, without its original context. We can restore that context by moving it above the declaration of `otherwise`.
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Move confusing comment about otherwise blocks in `lower_match_tree` This comment was historically inside a block guarded by `if let Some(otherwise_block) = otherwise`. When rust-lang#120978 made the “otherwise block” non-optional, it also flattened that region of code. Doing so left this comment awkwardly stranded above an unrelated line of code, without its original context. We can restore that context by moving it above the declaration of `otherwise`. r? `@Nadrieril`
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Move confusing comment about otherwise blocks in `lower_match_tree` This comment was historically inside a block guarded by `if let Some(otherwise_block) = otherwise`. When rust-lang#120978 made the “otherwise block” non-optional, it also flattened that region of code. Doing so left this comment awkwardly stranded above an unrelated line of code, without its original context. We can restore that context by moving it above the declaration of `otherwise`. r? ``@Nadrieril``
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Rollup merge of rust-lang#124064 - Zalathar:otherwise-block, r=Nadrieril Move confusing comment about otherwise blocks in `lower_match_tree` This comment was historically inside a block guarded by `if let Some(otherwise_block) = otherwise`. When rust-lang#120978 made the “otherwise block” non-optional, it also flattened that region of code. Doing so left this comment awkwardly stranded above an unrelated line of code, without its original context. We can restore that context by moving it above the declaration of `otherwise`. r? ``@Nadrieril``
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Match lowering was doing complicated things with block creation. As far as I can tell it was trying to avoid creating unneeded blocks, but of the three places that start out with
otherwise = &mut None, two of them calledotherwise.unwrap_or_else(|| self.cfg.start_new_block())anyway. As far as I can tell the only place where this PR makes a difference is inlower_match_tree, which did indeed sometimes avoid creating the unreachable final block + FakeRead. Unless this is important I propose we do the naive thing instead.I have not checked all the graph isomorphisms by hand, but at a glance the test diff looks sensible.
r? @matthewjasper