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AST: TypeChecker::conformsToProtocol() => ModuleDecl::checkConformance()

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This commit is contained in:
Slava Pestov
2024-01-16 15:18:44 -05:00
parent 1e950b1725
commit 14d1fcb51a
35 changed files with 151 additions and 193 deletions
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12
lib/SIL/Utils/DynamicCasts.cpp
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@@ -103,7 +103,7 @@ classifyDynamicCastToProtocol(ModuleDecl *M, CanType source, CanType target,
if (!TargetProtocol)
return DynamicCastFeasibility::MaySucceed;
// If the target is a parameterized protocol type, conformsToProtocol
// If the target is a parameterized protocol type, checkConformance
// is insufficient to prove the feasibility of the cast as it does not
// check the additional requirements.
// FIXME: This is a weak predicate that doesn't take into account
@@ -111,9 +111,9 @@ classifyDynamicCastToProtocol(ModuleDecl *M, CanType source, CanType target,
if (isa<ParameterizedProtocolType>(unwrapExistential(target)))
return DynamicCastFeasibility::MaySucceed;
// If conformsToProtocol returns a valid conformance, then all requirements
// were proven by the type checker.
if (M->conformsToProtocol(source, TargetProtocol))
// If checkConformance() returns a valid conformance, then all conditional
// requirements were satisfied.
if (M->checkConformance(source, TargetProtocol))
return DynamicCastFeasibility::WillSucceed;
auto *SourceNominalTy = source.getAnyNominal();
@@ -141,14 +141,14 @@ classifyDynamicCastToProtocol(ModuleDecl *M, CanType source, CanType target,
}
// The WillFail conditions below assume any possible conformance on the
// nominal source type has been ruled out. The prior conformsToProtocol query
// nominal source type has been ruled out. The prior checkConformance query
// identified any definite conformance. Now check if there is already a known
// conditional conformance on the nominal type with requirements that were
// not proven.
//
// TODO: The TypeChecker can easily prove that some requirements cannot be
// met. Returning WillFail in those cases would be more optimal. To do that,
// the conformsToProtocol interface needs to be reformulated as a query, and
// the checkConformance interface needs to be reformulated as a query, and
// the implementation, including checkGenericArguments, needs to be taught to
// recognize that types with archetypes may potentially succeed.
if (auto conformance = M->lookupConformance(source, TargetProtocol)) {