AST: Generalize GenericEnvironment::maybeApplyOuterSubstitutions()

Author: slavapestov

include/swift/AST/SubstitutionMap.h

@@ -324,6 +324,19 @@ struct LookUpConformanceInOverrideSubs {
                                     ProtocolDecl *proto) const;
 };
 
+// Substitute the outer generic parameters from a substitution map, ignoring
+/// inner generic parameters with a given depth.
+struct OuterSubstitutions {
+  SubstitutionMap subs;
+  unsigned depth;
+
+  bool isUnsubstitutedTypeParameter(Type type) const;
+  Type operator()(SubstitutableType *type) const;
+  ProtocolConformanceRef operator()(CanType dependentType,
+                                    Type conformingReplacementType,
+                                    ProtocolDecl *conformedProtocol) const;
+};
+
 } // end namespace swift
 
 namespace llvm {

lib/AST/GenericEnvironment.cpp

@@ -291,48 +291,6 @@ GenericEnvironment::getMappingIfPresent(GenericParamKey key) const {
   return std::nullopt;
 }
 
-namespace {
-
-/// Substitute the outer generic parameters from a substitution map, ignoring
-/// innter generic parameters with a given depth.
-struct SubstituteOuterFromSubstitutionMap {
-  SubstitutionMap subs;
-  unsigned depth;
-
-  /// Whether this is a type parameter that should not be substituted.
-  bool isUnsubstitutedTypeParameter(Type type) const {
-    if (!type->isTypeParameter())
-      return false;
-
-    if (auto depMemTy = type->getAs<DependentMemberType>())
-      return isUnsubstitutedTypeParameter(depMemTy->getBase());
-
-    if (auto genericParam = type->getAs<GenericTypeParamType>())
-      return genericParam->getDepth() >= depth;
-
-    return false;
-  }
-
-  Type operator()(SubstitutableType *type) const {
-    if (isUnsubstitutedTypeParameter(type))
-      return Type(type);
-
-    return QuerySubstitutionMap{subs}(type);
-  }
-
-  ProtocolConformanceRef operator()(CanType dependentType,
-                                    Type conformingReplacementType,
-                                    ProtocolDecl *conformedProtocol) const {
-    if (isUnsubstitutedTypeParameter(dependentType))
-      return ProtocolConformanceRef(conformedProtocol);
-
-    return LookUpConformanceInSubstitutionMap(subs)(
-        dependentType, conformingReplacementType, conformedProtocol);
-  }
-};
-
-}
-
 Type
 GenericEnvironment::maybeApplyOuterContextSubstitutions(Type type) const {
   switch (getKind()) {
@@ -342,10 +300,8 @@ GenericEnvironment::maybeApplyOuterContextSubstitutions(Type type) const {
 
   case Kind::OpenedElement:
   case Kind::Opaque: {
-    auto packElements = getGenericSignature().getInnermostGenericParams();
-    auto elementDepth = packElements.front()->getDepth();
-    SubstituteOuterFromSubstitutionMap replacer{
-        getOuterSubstitutions(), elementDepth};
+    OuterSubstitutions replacer{
+        getOuterSubstitutions(), getGenericSignature()->getMaxDepth()};
     return type.subst(replacer, replacer);
   }
   }

lib/AST/SubstitutionMap.cpp

@@ -666,3 +666,35 @@ SubstitutionMap SubstitutionMap::mapIntoTypeExpansionContext(
                      SubstFlags::SubstituteOpaqueArchetypes |
                      SubstFlags::PreservePackExpansionLevel);
 }
+
+bool OuterSubstitutions::isUnsubstitutedTypeParameter(Type type) const {
+  if (!type->isTypeParameter())
+    return false;
+
+  if (auto depMemTy = type->getAs<DependentMemberType>())
+    return isUnsubstitutedTypeParameter(depMemTy->getBase());
+
+  if (auto genericParam = type->getAs<GenericTypeParamType>())
+    return genericParam->getDepth() >= depth;
+
+  return false;
+}
+
+Type OuterSubstitutions::operator()(SubstitutableType *type) const {
+  if (isUnsubstitutedTypeParameter(type))
+    return Type(type);
+
+  return QuerySubstitutionMap{subs}(type);
+}
+
+ProtocolConformanceRef OuterSubstitutions::operator()(
+                                        CanType dependentType,
+                                        Type conformingReplacementType,
+                                        ProtocolDecl *conformedProtocol) const {
+  if (isUnsubstitutedTypeParameter(dependentType))
+    return ProtocolConformanceRef(conformedProtocol);
+
+  return LookUpConformanceInSubstitutionMap(subs)(
+      dependentType, conformingReplacementType, conformedProtocol);
+}
+