AST: Push ValueDecl::isSettable() down to AbstractStorageDecl

Author: slavapestov

include/swift/AST/Decl.h

@@ -2588,12 +2588,6 @@ class ValueDecl : public Decl {
   void setInterfaceType(Type type);
 
   bool hasValidSignature() const;
-
-  /// isSettable - Determine whether references to this decl may appear
-  /// on the left-hand side of an assignment or as the operand of a
-  /// `&` or 'inout' operator.
-  bool isSettable(const DeclContext *UseDC,
-                  const DeclRefExpr *base = nullptr) const;
 
   /// isInstanceMember - Determine whether this value is an instance member
   /// of an enum or protocol.
@@ -4546,6 +4540,12 @@ class AbstractStorageDecl : public ValueDecl {
     return getImplInfo().supportsMutation();
   }
 
+  /// isSettable - Determine whether references to this decl may appear
+  /// on the left-hand side of an assignment or as the operand of a
+  /// `&` or 'inout' operator.
+  bool isSettable(const DeclContext *UseDC,
+                  const DeclRefExpr *base = nullptr) const;
+
   /// Are there any accessors for this declaration, including implicit ones?
   bool hasAnyAccessors() const {
     return !getAllAccessors().empty();
@@ -7099,14 +7099,13 @@ class MissingMemberDecl : public Decl {
   }
 };
 
-inline bool ValueDecl::isSettable(const DeclContext *UseDC,
-                                  const DeclRefExpr *base) const {
-  if (auto vd = dyn_cast<VarDecl>(this)) {
+inline bool AbstractStorageDecl::isSettable(const DeclContext *UseDC,
+                                            const DeclRefExpr *base) const {
+  if (auto vd = dyn_cast<VarDecl>(this))
     return vd->isSettable(UseDC, base);
-  } else if (auto sd = dyn_cast<SubscriptDecl>(this)) {
-    return sd->supportsMutation();
-  } else
-    return false;
+
+  auto sd = cast<SubscriptDecl>(this);
+  return sd->supportsMutation();
 }
 
 inline void

lib/SILGen/SILGenProlog.cpp

@@ -342,7 +342,7 @@ static void emitCaptureArguments(SILGenFunction &SGF,
                                  CapturedValue capture,
                                  uint16_t ArgNo) {
 
-  auto *VD = capture.getDecl();
+  auto *VD = cast<VarDecl>(capture.getDecl());
   SILLocation Loc(VD);
   Loc.markAsPrologue();
 

lib/Sema/TypeCheckDeclOverride.cpp

@@ -893,19 +893,20 @@ static void checkOverrideAccessControl(ValueDecl *baseDecl, ValueDecl *decl,
     bool shouldDiagnose = !decl->isAccessibleFrom(scopeDC);
 
     bool shouldDiagnoseSetter = false;
-    if (!shouldDiagnose && baseDecl->isSettable(dc)){
-      auto matchASD = cast<AbstractStorageDecl>(baseDecl);
-      if (matchASD->isSetterAccessibleFrom(dc)) {
-        auto matchSetterAccessScope =
-          matchASD->getSetterFormalAccessScope(dc);
-        auto requiredSetterAccessScope =
-          matchSetterAccessScope.intersectWith(classAccessScope);
-        auto setterScopeDC = requiredSetterAccessScope->getDeclContext();
-
-        const auto *ASD = cast<AbstractStorageDecl>(decl);
-        shouldDiagnoseSetter =
-            ASD->isSettable(setterScopeDC) &&
-            !ASD->isSetterAccessibleFrom(setterScopeDC);
+    if (auto matchASD = dyn_cast<AbstractStorageDecl>(baseDecl)) {
+      if (!shouldDiagnose && matchASD->isSettable(dc)){
+        if (matchASD->isSetterAccessibleFrom(dc)) {
+          auto matchSetterAccessScope =
+            matchASD->getSetterFormalAccessScope(dc);
+          auto requiredSetterAccessScope =
+            matchSetterAccessScope.intersectWith(classAccessScope);
+          auto setterScopeDC = requiredSetterAccessScope->getDeclContext();
+
+          const auto *ASD = cast<AbstractStorageDecl>(decl);
+          shouldDiagnoseSetter =
+              ASD->isSettable(setterScopeDC) &&
+              !ASD->isSetterAccessibleFrom(setterScopeDC);
+        }
       }
     }
 
@@ -1594,7 +1595,7 @@ static bool checkSingleOverride(ValueDecl *override, ValueDecl *base) {
     // Make sure we're not overriding a settable property with a non-settable
     // one.  The only reasonable semantics for this would be to inherit the
     // setter but override the getter, and that would be surprising at best.
-    if (baseIsSettable && !override->isSettable(override->getDeclContext())) {
+    if (baseIsSettable && !overrideASD->isSettable(override->getDeclContext())) {
       diags.diagnose(overrideASD, diag::override_mutable_with_readonly_property,
                      overrideASD->getBaseName().getIdentifier());
       diags.diagnose(baseASD, diag::property_override_here);

lib/Sema/TypeCheckProtocol.cpp

@@ -398,16 +398,16 @@ swift::matchWitness(
       return RequirementMatch(witness, MatchKind::StaticNonStaticConflict);
 
     // If the requirement is settable and the witness is not, reject it.
-    if (req->isSettable(req->getDeclContext()) &&
-        !witness->isSettable(witness->getDeclContext()))
+    if (reqASD->isSettable(req->getDeclContext()) &&
+        !witnessASD->isSettable(witness->getDeclContext()))
       return RequirementMatch(witness, MatchKind::SettableConflict);
 
     // Validate that the 'mutating' bit lines up for getters and setters.
     if (!reqASD->isGetterMutating() && witnessASD->isGetterMutating())
       return RequirementMatch(getStandinForAccessor(witnessASD, AccessorKind::Get),
                               MatchKind::MutatingConflict);
 
-    if (req->isSettable(req->getDeclContext())) {
+    if (reqASD->isSettable(req->getDeclContext())) {
       if (!reqASD->isSetterMutating() && witnessASD->isSetterMutating())
         return RequirementMatch(getStandinForAccessor(witnessASD, AccessorKind::Set),
                                 MatchKind::MutatingConflict);
@@ -1197,15 +1197,17 @@ bool WitnessChecker::checkWitnessAccess(ValueDecl *requirement,
       return true;
   }
 
-  if (requirement->isSettable(DC)) {
-    *isSetter = true;
+  if (auto *requirementASD = dyn_cast<AbstractStorageDecl>(requirement)) {
+    if (requirementASD->isSettable(DC)) {
+      *isSetter = true;
 
-    auto ASD = cast<AbstractStorageDecl>(witness);
+      auto witnessASD = cast<AbstractStorageDecl>(witness);
 
-    // See above about the forConformance flag.
-    if (!ASD->isSetterAccessibleFrom(actualScopeToCheck.getDeclContext(),
-                                     /*forConformance=*/true))
-      return true;
+      // See above about the forConformance flag.
+      if (!witnessASD->isSetterAccessibleFrom(actualScopeToCheck.getDeclContext(),
+                                              /*forConformance=*/true))
+        return true;
+    }
   }
 
   return false;