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Symbol resolution of ability members can come from unique defs or unique shadows

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Ayaz Hafiz 2022-09-21 10:23:49 -05:00
parent 454f3634fd
commit 67d0a3d36f
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1 changed files with 33 additions and 1 deletions
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34
crates/compiler/can/src/def.rs
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@ -462,7 +462,39 @@ fn canonicalize_claimed_ability_impl<'a>(
}
};
match scope.lookup_ability_member_shadow(member_symbol) {
// There are two options for how the implementation symbol is defined.
//
// OPTION-1: The implementation identifier is the only identifier of that name in the
// scope. For example,
//
// interface F imports [] exposes []
//
// Hello := {} has [Encoding.{ toEncoder }]
//
// toEncoder = \@Hello {} -> ...
//
// In this case, we just do a simple lookup in the scope to find our
// `toEncoder` impl.
//
// OPTION-2: The implementation identifier is a unique shadow of the ability member,
// which has also been explicitly imported. For example,
//
// interface F imports [Encoding.{ toEncoder }] exposes []
//
// Hello := {} has [Encoding.{ toEncoder }]
//
// toEncoder = \@Hello {} -> ...
//
// In this case, we allow the `F` module's `toEncoder` def to shadow
// `toEncoder` only to define this specialization's `toEncoder`.
//
// To handle both cases, try checking for a shadow first, then check for a direct
// reference. We want to check for a direct reference second so that if there is a
// shadow, we won't accidentally grab the imported symbol.
let opt_impl_symbol = (scope.lookup_ability_member_shadow(member_symbol))
.or_else(|| scope.lookup_str(label_str, region).ok());
match opt_impl_symbol {
Some(impl_symbol) => Ok((member_symbol, impl_symbol)),
None => {
env.problem(Problem::ImplementationNotFound {