[TBDGen] Explicitly walk members of stored static vars.

Unlike some other vars, these members are not also listed at the top
level, adjacent to the VarDecl.

Author: huonw

include/swift/AST/Decl.h

@@ -4099,6 +4099,10 @@ class AbstractStorageDecl : public ValueDecl {
 
   FuncDecl *getAccessorFunction(AccessorKind accessor) const;
 
+  /// \brief Push all of the accessor functions associated with this VarDecl
+  /// onto `decls`.
+  void getAllAccessorFunctions(SmallVectorImpl<Decl *> &decls) const;
+
   /// \brief Turn this into a computed variable, providing a getter and setter.
   void makeComputed(SourceLoc LBraceLoc, FuncDecl *Get, FuncDecl *Set,
                     FuncDecl *MaterializeForSet, SourceLoc RBraceLoc);

lib/AST/Decl.cpp

@@ -3430,6 +3430,28 @@ FuncDecl *AbstractStorageDecl::getAccessorFunction(AccessorKind kind) const {
   llvm_unreachable("bad accessor kind!");
 }
 
+void AbstractStorageDecl::getAllAccessorFunctions(
+    SmallVectorImpl<Decl *> &decls) const {
+  auto tryPush = [&](Decl *decl) {
+    if (decl)
+      decls.push_back(decl);
+  };
+
+  tryPush(getGetter());
+  tryPush(getSetter());
+  tryPush(getMaterializeForSetFunc());
+
+  if (hasObservers()) {
+    tryPush(getDidSetFunc());
+    tryPush(getWillSetFunc());
+  }
+
+  if (hasAddressors()) {
+    tryPush(getAddressor());
+    tryPush(getMutableAddressor());
+  }
+}
+
 void AbstractStorageDecl::configureGetSetRecord(GetSetRecord *getSetInfo,
                                                 FuncDecl *getter,
                                                 FuncDecl *setter,

lib/TBDGen/TBDGen.cpp

@@ -96,6 +96,8 @@ class TBDGenVisitor : public ASTVisitor<TBDGenVisitor> {
       addMembers(ED->getMembers());
     else if (auto NTD = dyn_cast<NominalTypeDecl>(D))
       addMembers(NTD->getMembers());
+    else if (auto VD = dyn_cast<VarDecl>(D))
+      VD->getAllAccessorFunctions(members);
 
     for (auto member : members) {
       ASTVisitor::visit(member);
@@ -221,9 +223,11 @@ void TBDGenVisitor::visitVarDecl(VarDecl *VD) {
     // like globals.
     if (!FileHasEntryPoint)
       addSymbol(SILDeclRef(VD, SILDeclRef::Kind::GlobalAccessor));
-  }
 
-  visitMembers(VD);
+    // In this case, the members of the VarDecl don't also appear as top-level
+    // decls, so we need to explicitly walk them.
+    visitMembers(VD);
+  }
 }
 
 void TBDGenVisitor::visitNominalTypeDecl(NominalTypeDecl *NTD) {