Miscellaneous style improvements

Author: beccadax

include/swift/AST/Decl.h

@@ -985,7 +985,7 @@ class alignas(1 << DeclAlignInBits) Decl : public ASTAllocated<Decl> {
   /// returns the imported declaration. Otherwise return \c nullptr.
   ///
   /// \seeAlso ExtensionDecl::isObjCInterface()
-  Decl *getObjCInterfaceDecl() const;
+  Decl *getImplementedObjCDecl() const;
 
   /// If this is the ObjC interface of a declaration implemented in Swift,
   /// returns the implementating declaration. Otherwise return \c nullptr.

lib/ClangImporter/ClangImporter.cpp

@@ -5182,7 +5182,7 @@ swift::extractNearestSourceLoc(const ObjCInterfaceAndImplementation &pair) {
   return extractNearestSourceLoc(pair.implementationDecl);
 }
 
-Decl *Decl::getObjCInterfaceDecl() const {
+Decl *Decl::getImplementedObjCDecl() const {
   if (hasClangNode())
     // This *is* the interface, if there is one.
     return nullptr;

lib/IRGen/GenClass.cpp

@@ -1341,6 +1341,9 @@ namespace {
     llvm::Constant *getClassMetadataRef() {
       auto *theClass = getClass();
 
+      // If this is truly an imported ObjC class, with no @_objcImplementation,
+      // someone else will emit the ObjC metadata symbol and we simply want to
+      // use it.
       if (theClass->hasClangNode() &&
           !theClass->getObjCImplementationDecl())
         return IGM.getAddrOfObjCClass(theClass, NotForDefinition);

lib/Sema/TypeCheckAttr.cpp

@@ -1392,7 +1392,7 @@ visitObjCImplementationAttr(ObjCImplementationAttr *attr) {
     return;
   }
 
-  if (!attr->isCategoryNameInvalid() && !ED->getObjCInterfaceDecl()) {
+  if (!attr->isCategoryNameInvalid() && !ED->getImplementedObjCDecl()) {
     diagnose(attr->getLocation(),
              diag::attr_objc_implementation_category_not_found,
              attr->CategoryName, CD);

lib/Sema/TypeCheckDeclObjC.cpp

@@ -1872,7 +1872,7 @@ static bool isObjCImplementation(AbstractFunctionDecl *method,
     return false;
 
   auto contextInterface =
-      dyn_cast<IterableDeclContext>(ext->getObjCInterfaceDecl());
+      dyn_cast<IterableDeclContext>(ext->getImplementedObjCDecl());
 
   for (auto otherMember : contextInterface->getMembers()) {
     auto otherMethod = dyn_cast<AbstractFunctionDecl>(otherMember);
@@ -2046,7 +2046,7 @@ void markAsObjC(ValueDecl *D, ObjCReason reason,
 
     // Record the method in the type, if it's a member of one.
     if (auto tyDecl = D->getDeclContext()->getSelfNominalTypeDecl()) {
-      // FIXME: Should be able to check method->getObjCInterfaceDecl(), but we
+      // FIXME: Should be able to check method->getImplementedObjCDecl(), but we
       //        don't have that matching yet.
       if (!isObjCImplementation(method, selector))
         tyDecl->recordObjCMethod(method, selector);

lib/TBDGen/TBDGen.cpp

@@ -1014,7 +1014,7 @@ void TBDGenVisitor::visitDestructorDecl(DestructorDecl *DD) {
 }
 
 void TBDGenVisitor::visitExtensionDecl(ExtensionDecl *ED) {
-  if (auto CD = dyn_cast_or_null<ClassDecl>(ED->getObjCInterfaceDecl())) {
+  if (auto CD = dyn_cast_or_null<ClassDecl>(ED->getImplementedObjCDecl())) {
     // Generate symbols for the class instead of the extension.
     visitClassDecl(CD);
     return;