Correctly remove properties subsumed by init accessors from memberwise inits

The code to remove these subsumed properties was part of creating the
memberwise initializer declaration, which could lead to
inconsistencies with the newly-introduced request for gathering the
memberwise-initialized properties. Move the code into the computation
of the list of memberwise-initialized properties.

Also update a few more places that were effectively recomputing the
set of memberwise-initialized properties themselves over to the
request.

Author: DougGregor

lib/Index/Index.cpp

@@ -706,14 +706,7 @@ class IndexSwiftASTWalker : public SourceEntityWalker {
       return;
 
     unsigned CurLabel = 0;
-    for (auto Member : TypeContext->getMembers()) {
-      auto Prop = dyn_cast<VarDecl>(Member);
-      if (!Prop)
-        continue;
-
-      if (!Prop->isMemberwiseInitialized(/*preferDeclaredProperties=*/true))
-        continue;
-
+    for (auto Prop : TypeContext->getMemberwiseInitProperties()) {
       if (CurLabel == Args.size())
         break;
 

lib/Refactoring/Refactoring.cpp

@@ -3428,10 +3428,6 @@ collectMembersForInit(ResolvedCursorInfoPtr CursorInfo,
       continue;
     }
 
-    if (!varDecl->isMemberwiseInitialized(/*preferDeclaredProperties=*/true)) {
-      continue;
-    }
-
     auto patternBinding = varDecl->getParentPatternBinding();
     if (!patternBinding)
       continue;

lib/Sema/CodeSynthesis.cpp

@@ -294,13 +294,7 @@ static ConstructorDecl *createImplicitConstructor(NominalTypeDecl *decl,
   if (ICK == ImplicitConstructorKind::Memberwise) {
     assert(isa<StructDecl>(decl) && "Only struct have memberwise constructor");
 
-    std::multimap<VarDecl *, VarDecl *> initializedViaAccessor;
-    decl->collectPropertiesInitializableByInitAccessors(initializedViaAccessor);
-
     for (auto var : decl->getMemberwiseInitProperties()) {
-      if (initializedViaAccessor.count(var))
-        continue;
-
       accessLevel = std::min(accessLevel, var->getFormalAccess());
       params.push_back(createMemberwiseInitParameter(decl, Loc, var));
     }
@@ -1401,8 +1395,7 @@ ResolveEffectiveMemberwiseInitRequest::evaluate(Evaluator &evaluator,
   auto accessLevel = AccessLevel::Public;
   for (auto *member : decl->getMembers()) {
     auto *var = dyn_cast<VarDecl>(member);
-    if (!var ||
-        !var->isMemberwiseInitialized(/*preferDeclaredProperties*/ true))
+    if (!var || !var->isMemberwiseInitialized(/*preferDeclaredProperties=*/true))
       continue;
     accessLevel = std::min(accessLevel, var->getFormalAccess());
   }

lib/Sema/TypeCheckStorage.cpp

@@ -366,9 +366,25 @@ MemberwiseInitPropertiesRequest::evaluate(Evaluator &evaluator,
   computeLoweredProperties(decl, implDecl, LoweredPropertiesReason::Memberwise);
 
   SmallVector<VarDecl *, 4> results;
+  SmallPtrSet<VarDecl *, 4> subsumedViaInitAccessor;
+
   auto maybeAddProperty = [&](VarDecl *var) {
-    if (var->isMemberwiseInitialized(/*preferDeclaredProperties=*/true))
-      results.push_back(var);
+    // We only care about properties that are memberwise initialized.
+    if (!var->isMemberwiseInitialized(/*preferDeclaredProperties=*/true))
+      return;
+
+    // Add this property.
+    results.push_back(var);
+
+    // If this property has an init accessor, it subsumes all of the stored properties
+    // that the accessor initializes. Mark those stored properties as being subsumed; we'll
+    // get back to them later.
+    if (auto initAccessor = var->getAccessor(AccessorKind::Init)) {
+      if (auto initAttr = initAccessor->getAttrs().getAttribute<InitializesAttr>()) {
+        for (auto subsumed : initAttr->getPropertyDecls(initAccessor))
+          subsumedViaInitAccessor.insert(subsumed);
+      }
+    }
   };
 
   for (auto *member : decl->getCurrentMembers()) {
@@ -381,6 +397,14 @@ MemberwiseInitPropertiesRequest::evaluate(Evaluator &evaluator,
     });
   }
 
+  // If any properties were subsumed via init accessors, drop them from the list.
+  if (!subsumedViaInitAccessor.empty()) {
+    results.erase(std::remove_if(results.begin(), results.end(), [&](VarDecl *var) {
+                    return subsumedViaInitAccessor.contains(var);
+                  }),
+                  results.end());
+  }
+
   return decl->getASTContext().AllocateCopy(results);
 }