Clarify constructor splitting in exhaustiveness checking#80242
Merged
bors merged 13 commits intorust-lang:masterfrom Dec 23, 2020
Merged
Clarify constructor splitting in exhaustiveness checking#80242bors merged 13 commits intorust-lang:masterfrom
bors merged 13 commits intorust-lang:masterfrom
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I reworked the explanation of the algorithm completely to make it properly account for the various extensions we've added. This includes constructor splitting, which was previously not clearly included in the algorithm. This makes wildcards less magical; I added some detailed examples; and this distinguishes clearly between constructors that only make sense in patterns (like ranges) and those that make sense for values (like
Some). This reformulation had been floating around in my mind for a while, and I'm quite happy with how it turned out. Let me know how you feel about it.I also factored out all three cases of splitting (wildcards, ranges and slices) into dedicated structs to encapsulate the complicated bits.
I measured no perf impact but I don't trust my local measurements for refactors since #79284.
r? @varkor
@rustbot modify labels: +A-exhaustiveness-checking