Sema: Fix two bugs with type resolution of generic arguments [5.10] #69129
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Applying generic arguments to a variadic generic type uses the PackMatcher to build a mapping between generic parameters and arguments. The PackMatcher is symmetric, so there was an unexpected failure mode that wasn't handled: if the variadic generic type had some non-pack parameters, but the argument list was a single pack expansion type, the match would succeed, grouping all of the generic parameters into a single match. This is non-sensical, so we need to explicitly check for this case and diagnose it. This requires a new diagnostic, since otherwise the general diagnostic we emit for variadic generic type mismatches doesn't make sense, since it's complaining about there being too few generic parameters. Fixes rdar://116713961 / swiftlang#69012.
…ons, and reject pack expansion types there We used to disallow pack expansions in generic argument lists of protocols, but allow them for all other nominal types. However, we only actually checked that the pack expansions match up if the type itself was variadic. Fix this by repurposing Context::ProtocolGenericArgument into Context::ScalarGenericArgument, and using that when the type does not have a parameter pack. Context::GenericArgument is now Context::VariadicGenericArgument, and we only use it if the type has a parameter pack, in which case we use the PackMatcher, so any pack expansions in the wrong place are caught there. Fixes rdar://116716014 and swiftlang#69088.
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@swift-ci Please test |
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@swift-ci Please test |
hborla
approved these changes
Oct 12, 2023
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mainfor a while. I cherry-picked it to avoid merge conflicts)