AST: Simplify SubstitutionMap::lookupConformance()

Author: slavapestov

include/swift/SIL/SILCloner.h

@@ -85,6 +85,11 @@ struct SubstitutionMapWithLocalArchetypes {
                                     ProtocolDecl *proto) {
     if (isa<LocalArchetypeType>(origType))
       return swift::lookupConformance(substType, proto);
+
+    if (isa<PrimaryArchetypeType>(origType) ||
+        isa<PackArchetypeType>(origType))
+      origType = origType->mapTypeOutOfContext()->getCanonicalType();
+
     if (SubsMap)
       return SubsMap->lookupConformance(origType, proto);
 

lib/AST/SubstitutionMap.cpp

@@ -11,14 +11,11 @@
 //===----------------------------------------------------------------------===//
 //
 // This file defines the SubstitutionMap class. A SubstitutionMap packages
-// together a set of replacement types and protocol conformances for
-// specializing generic types.
+// together a set of replacement types and protocol conformances, given by
+// the generic parameters and conformance requirements of the substitution map's
+// input generic signature.
 //
-// SubstitutionMaps either have type parameters or archetypes as keys,
-// based on whether they were built from a GenericSignature or a
-// GenericEnvironment.
-//
-// To specialize a type, call Type::subst() with the right SubstitutionMap.
+// To substitute a type, call Type::subst() with the right SubstitutionMap.
 //
 //===----------------------------------------------------------------------===//
 
@@ -238,20 +235,9 @@ Type SubstitutionMap::lookupSubstitution(GenericTypeParamType *genericParam) con
 
 ProtocolConformanceRef
 SubstitutionMap::lookupConformance(CanType type, ProtocolDecl *proto) const {
-  if (empty())
-    return ProtocolConformanceRef::forInvalid();
-
-  // If we have an archetype, map out of the context so we can compute a
-  // conformance access path.
-  if (auto archetype = dyn_cast<ArchetypeType>(type)) {
-    if (!isa<OpaqueTypeArchetypeType>(archetype)) {
-      type = archetype->getInterfaceType()->getCanonicalType();
-    }
-  }
+  ASSERT(type->isTypeParameter());
 
-  // Error path: if we don't have a type parameter, there is no conformance.
-  // FIXME: Query concrete conformances in the generic signature?
-  if (!type->isTypeParameter())
+  if (empty())
     return ProtocolConformanceRef::forInvalid();
 
   auto genericSig = getGenericSignature();

lib/AST/TypeSubstitution.cpp

@@ -206,6 +206,10 @@ operator()(CanType dependentType, Type conformingReplacementType,
         /*allowMissing=*/true);
   }
 
+  if (isa<PrimaryArchetypeType>(dependentType) ||
+      isa<PackArchetypeType>(dependentType))
+    dependentType = dependentType->mapTypeOutOfContext()->getCanonicalType();
+
   auto result = Subs.lookupConformance(dependentType, conformedProtocol);
   if (!result.isInvalid())
     return result;

lib/SILOptimizer/Utils/ConstExpr.cpp

@@ -426,7 +426,8 @@ SymbolicValue ConstExprFunctionState::computeConstantValue(SILValue value) {
   // Try to resolve a witness method against our known conformances.
   if (auto *wmi = dyn_cast<WitnessMethodInst>(value)) {
     auto conf = substitutionMap.lookupConformance(
-        wmi->getLookupType(), wmi->getConformance().getRequirement());
+        wmi->getLookupType()->mapTypeOutOfContext()->getCanonicalType(),
+        wmi->getConformance().getRequirement());
     if (conf.isInvalid())
       return getUnknown(evaluator, value,
                         UnknownReason::UnknownWitnessMethodConformance);