AST: Remove SubscriptDecl::isSettable()

Author: slavapestov

include/swift/AST/Decl.h

@@ -5489,9 +5489,6 @@ class SubscriptDecl : public GenericContext, public AbstractStorageDecl {
   /// element types.
   void computeType();
 
-  /// Returns whether the result of the subscript operation can be set.
-  bool isSettable() const;
-
   /// Determine the kind of Objective-C subscripting this declaration
   /// implies.
   ObjCSubscriptKind getObjCSubscriptKind() const;
@@ -7107,7 +7104,7 @@ inline bool ValueDecl::isSettable(const DeclContext *UseDC,
   if (auto vd = dyn_cast<VarDecl>(this)) {
     return vd->isSettable(UseDC, base);
   } else if (auto sd = dyn_cast<SubscriptDecl>(this)) {
-    return sd->isSettable();
+    return sd->supportsMutation();
   } else
     return false;
 }

lib/AST/Decl.cpp

@@ -5062,10 +5062,6 @@ bool VarDecl::isLazilyInitializedGlobal() const {
   return !sourceFileContext->isScriptMode();
 }
 
-bool SubscriptDecl::isSettable() const {
-  return supportsMutation();
-}
-
 SourceRange VarDecl::getSourceRange() const {
   if (auto Param = dyn_cast<ParamDecl>(this))
     return Param->getSourceRange();

lib/ClangImporter/ImportDecl.cpp

@@ -6694,7 +6694,7 @@ SwiftDeclConverter::importSubscript(Decl *decl,
     if (setter && existingSubscript && getterAndSetterInSameType) {
       // Can we update the subscript by adding the setter?
       if (existingSubscript->hasClangNode() &&
-          !existingSubscript->isSettable()) {
+          !existingSubscript->supportsMutation()) {
         // Create the setter thunk.
         auto setterThunk = buildSubscriptSetterDecl(
             Impl, existingSubscript, setter, elementTy,

lib/IRGen/GenDecl.cpp

@@ -242,7 +242,7 @@ class CategoryInitializerVisitor
     llvm::Value *getterArgs[] = {classMetadata, sel, imp, types};
     Builder.CreateCall(class_replaceMethod, getterArgs);
 
-    if (subscript->isSettable()) {
+    if (subscript->supportsMutation()) {
       emitObjCSetterDescriptorParts(IGM, subscript,
                                     name, types, imp);
       sel = Builder.CreateCall(IGM.getObjCSelRegisterNameFn(),

lib/IRGen/GenObjC.cpp

@@ -1242,7 +1242,7 @@ SILFunction *irgen::emitObjCSetterDescriptorParts(IRGenModule &IGM,
                                                   llvm::Constant *&selectorRef,
                                                   llvm::Constant *&atEncoding,
                                                   llvm::Constant *&impl) {
-  assert(subscript->isSettable() && "not a settable subscript?!");
+  assert(subscript->supportsMutation() && "not a settable subscript?!");
 
   Selector setterSel(subscript, Selector::ForSetter);
   selectorRef = IGM.getAddrOfObjCMethodName(setterSel.str());

lib/Sema/CSDiag.cpp

@@ -3662,7 +3662,7 @@ bool FailureDiagnosis::diagnoseSubscriptErrors(SubscriptExpr *SE,
           // Classify how close this match is.  Non-subscript decls don't match.
           auto subscriptDecl = dyn_cast_or_null<SubscriptDecl>(cand.getDecl());
           if (!subscriptDecl ||
-              (inAssignmentDestination && !subscriptDecl->isSettable()))
+              (inAssignmentDestination && !subscriptDecl->supportsMutation()))
             return {CC_GeneralMismatch, {}};
 
           // Check whether the self type matches.

lib/Sema/CSDiagnostics.cpp

@@ -1452,7 +1452,7 @@ bool AssignmentFailure::diagnoseAsError() {
     // If the underlying expression was a read-only subscript, diagnose that.
     if (auto *SD = dyn_cast_or_null<SubscriptDecl>(choice->getDecl())) {
       StringRef message;
-      if (!SD->isSettable())
+      if (!SD->supportsMutation())
         message = "subscript is get-only";
       else if (!SD->isSetterAccessibleFrom(DC))
         message = "subscript setter is inaccessible";

lib/Sema/TypeCheckDecl.cpp

@@ -2878,7 +2878,7 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
       checkDynamicSelfType(SD, SD->getValueInterfaceType());
 
       if (SD->getValueInterfaceType()->hasDynamicSelfType() &&
-          SD->isSettable()) {
+          SD->supportsMutation()) {
         SD->diagnose(diag::dynamic_self_in_mutable_subscript);
       }
     }

lib/Serialization/Deserialization.cpp

@@ -3859,7 +3859,7 @@ class swift::DeclDeserializer {
       return nullptr;
     }
 
-    if (subscript->isSettable()) {
+    if (subscript->supportsMutation()) {
       if (auto setterAccess = getActualAccessLevel(rawSetterAccessLevel)) {
         subscript->setSetterAccess(*setterAccess);
       } else {

lib/Serialization/Serialization.cpp

@@ -3649,7 +3649,7 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
     uint8_t rawAccessLevel =
       getRawStableAccessLevel(subscript->getFormalAccess());
     uint8_t rawSetterAccessLevel = rawAccessLevel;
-    if (subscript->isSettable())
+    if (subscript->supportsMutation())
       rawSetterAccessLevel =
         getRawStableAccessLevel(subscript->getSetterFormalAccess());
     uint8_t rawStaticSpelling =