Change match desugaring to degenerate to if-else-if chains #29776
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nikomatsakis
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It would be great to land this ASAP, since this bug is blocking Servo's rustup :-) |
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r+ with the typos fixed |
large matches that fallback to Eq. When we encounter a case where the test being performed does not inform the candidate at all, we just stop testing the candidates at that point, rather than adding the candidate to both outcomes. The former behavior was not WRONG, but it generated a lot of code, whereas this new behavior degenerates to an if-else-if tree. Fixes rust-lang#29740.
nikomatsakis
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@bors r=nrc |
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📌 Commit 662232c has been approved by |
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@bors p=1 (blocking servo) |
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⌛ Testing commit 662232c with merge b785ff9... |
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💔 Test failed - auto-mac-64-opt |
bothered to track down for a regresson test. /me hopes no one notices
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@bors r=nrc p=1 |
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📌 Commit a5e3625 has been approved by |
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⌛ Testing commit a5e3625 with merge 20f4e58... |
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💔 Test failed - auto-mac-64-opt |
Manishearth
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In previous PRs, I changed the match desugaring to generate more efficient code for ints/chars and the like. But this doesn't help when you're matching strings, ranges, or other crazy complex things (leading to rust-lang#29740). This commit restructures match desugaring *yet again* to handle that case better -- basically we now degenerate to an if-else-if chain in such cases. ~~Note that this builds on rust-lang#29763 which will hopefully land soon. So ignore the first few commits.~~ landed now r? @Aatch since he's been reviewing the other commits in this series
Manishearth
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Fails tidy, needs Manishearth@4f65538 |
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In previous PRs, I changed the match desugaring to generate more efficient code for ints/chars and the like. But this doesn't help when you're matching strings, ranges, or other crazy complex things (leading to #29740). This commit restructures match desugaring yet again to handle that case better -- basically we now degenerate to an if-else-if chain in such cases.
Note that this builds on #29763 which will hopefully land soon. So ignore the first few commits.landed nowr? @Aatch since he's been reviewing the other commits in this series