AST: Remove useDC parameter from typeEraseOpenedArchetypesWithRoot()

Author: slavapestov

include/swift/AST/Types.h

@@ -759,8 +759,7 @@ class alignas(1 << TypeAlignInBits) TypeBase
 
   /// Replace opened archetypes with the given root with their most
   /// specific non-dependent upper bounds throughout this type.
-  Type typeEraseOpenedArchetypesWithRoot(const OpenedArchetypeType *root,
-                                         const DeclContext *useDC) const;
+  Type typeEraseOpenedArchetypesWithRoot(const OpenedArchetypeType *root) const;
 
   /// Given a declaration context, returns a function type with the 'self'
   /// type curried as the input if the declaration context describes a type.

lib/AST/Type.cpp

@@ -607,15 +607,15 @@ void TypeBase::getRootOpenedExistentials(
 }
 
 Type TypeBase::typeEraseOpenedArchetypesWithRoot(
-    const OpenedArchetypeType *root, const DeclContext *useDC) const {
+    const OpenedArchetypeType *root) const {
   assert(root->isRoot() && "Expected a root archetype");
 
   Type type = Type(const_cast<TypeBase *>(this));
   if (!hasOpenedExistential())
     return type;
 
-  const auto sig = root->getASTContext().getOpenedExistentialSignature(
-      root->getExistentialType(), useDC->getGenericSignatureOfContext());
+  auto *env = root->getGenericEnvironment();
+  auto sig = env->getGenericSignature();
 
   unsigned metatypeDepth = 0;
 
@@ -665,9 +665,8 @@ Type TypeBase::typeEraseOpenedArchetypesWithRoot(
         return llvm::None;
       }
 
-      if (!root->isEqual(archetype->getRoot())) {
+      if (archetype->getGenericEnvironment() != env)
         return Type(ty);
-      }
 
       Type erasedTy;
       if (root->isEqual(archetype)) {

lib/Sema/CSApply.cpp

@@ -881,7 +881,7 @@ namespace {
       resultTy = cs.getType(result);
       if (resultTy->hasOpenedExistentialWithRoot(record.Archetype)) {
         Type erasedTy = resultTy->typeEraseOpenedArchetypesWithRoot(
-            record.Archetype, dc);
+            record.Archetype);
         auto range = result->getSourceRange();
         result = coerceToType(result, erasedTy, locator);
         // FIXME: Implement missing tuple-to-tuple conversion
@@ -1591,7 +1591,7 @@ namespace {
           // Erase opened existentials from the type of the thunk; we're
           // going to open the existential inside the thunk's body.
           containerTy = containerTy->typeEraseOpenedArchetypesWithRoot(
-              knownOpened->second, dc);
+              knownOpened->second);
           selfTy = containerTy;
         }
       }
@@ -1674,7 +1674,7 @@ namespace {
           // existential.
           if (openedExistential) {
             refType = refType->typeEraseOpenedArchetypesWithRoot(
-                baseTy->castTo<OpenedArchetypeType>(), dc);
+                baseTy->castTo<OpenedArchetypeType>());
           }
 
           return refType;
@@ -1885,7 +1885,7 @@ namespace {
           if (knownOpened != solution.OpenedExistentialTypes.end()) {
             curryThunkTy =
                 curryThunkTy
-                    ->typeEraseOpenedArchetypesWithRoot(knownOpened->second, dc)
+                    ->typeEraseOpenedArchetypesWithRoot(knownOpened->second)
                     ->castTo<FunctionType>();
           }
         }