From b1aff68da99cec130fee362aa045bc9ea5cdd8dc Mon Sep 17 00:00:00 2001
From: Joe Groff <jgroff@apple.com>
Date: Sat, 15 Jun 2013 00:41:32 +0000
Subject: [PATCH] Allow [class_protocol] protocols to be [objc].

Swift SVN r5591
---
 include/swift/AST/Diagnostics.def |  2 ++
 lib/IRGen/GenProto.cpp            |  1 +
 lib/Sema/TypeCheckDecl.cpp        | 36 +++++++++++++++++++++++++------
 3 files changed, 32 insertions(+), 7 deletions(-)

diff --git a/include/swift/AST/Diagnostics.def b/include/swift/AST/Diagnostics.def
index ff178f7ffab..02684b4ec34 100644
--- a/include/swift/AST/Diagnostics.def
+++ b/include/swift/AST/Diagnostics.def
@@ -1023,6 +1023,8 @@ ERROR(conversion_params,sema_tcd,none,
       "conversion function %0 has non-defaulted parameters", (Identifier))
 ERROR(invalid_objc_decl,sema_tcd,none,
       "only classes and their methods can be declared 'objc'", ())
+ERROR(objc_protocol_not_class_protocol,sema_tcd,none,
+      "only [class_protocol] protocols can be declared 'objc'", ())
 ERROR(invalid_iboutlet,sema_tcd,none,
       "only properties can be declared 'iboutlet'", ())
 ERROR(invalid_ibaction_decl,sema_tcd,none,
diff --git a/lib/IRGen/GenProto.cpp b/lib/IRGen/GenProto.cpp
index a3cb773f718..76d37ffcbce 100644
--- a/lib/IRGen/GenProto.cpp
+++ b/lib/IRGen/GenProto.cpp
@@ -1546,6 +1546,7 @@ static void buildValueWitnessFunction(IRGenModule &IGM,
         = emitTypeMetadataRefForClassBoundedExistential(IGF, existential,
                                                         concreteType);
       IGF.Builder.CreateRet(result);
+      
     } else {
       llvm::Value *result
         = emitTypeMetadataRefForOpaqueExistential(IGF, obj, concreteType);
diff --git a/lib/Sema/TypeCheckDecl.cpp b/lib/Sema/TypeCheckDecl.cpp
index d0c1c10d426..56e7d52df92 100644
--- a/lib/Sema/TypeCheckDecl.cpp
+++ b/lib/Sema/TypeCheckDecl.cpp
@@ -461,6 +461,20 @@ public:
   void visitProtocolDecl(ProtocolDecl *PD) {
     if (IsSecondPass)
       return;
+    
+    // The protocol requires ObjC interop if the protocol or any of the
+    // protocols it refines are [objc].
+    if (PD->getAttrs().isObjC())
+      PD->setIsObjC(true);
+    else {
+      PD->setIsObjC(false);
+      for (auto *parent : PD->getProtocols()) {
+        if (parent->isObjC()) {
+          PD->setIsObjC(true);
+          break;
+        }
+      }
+    }
 
     // Fix the 'This' associated type.
     TypeAliasDecl *thisDecl = nullptr;
@@ -1116,17 +1130,25 @@ void DeclChecker::validateAttributes(ValueDecl *VD) {
   };
   
   if (Attrs.isObjC()) {
-    // Only classes, instance properties, and methods can be ObjC.
-    bool isLegal = false;
+    // Only classes, class protocols, instance properties, and methods can be
+    // ObjC.
+    Optional<Diag<>> error;
     if (isa<ClassDecl>(VD)) {
-      isLegal = true;
+      /* ok */
     } else if (isa<FuncDecl>(VD) && isInClassContext(VD)) {
-      isLegal = !isOperator;
+      if (isOperator)
+        error = diag::invalid_objc_decl;
     } else if (isa<VarDecl>(VD) && isInClassContext(VD)) {
-      isLegal = true;
+      /* ok */
+    } else if (auto *protocol = dyn_cast<ProtocolDecl>(VD)) {
+      if (!protocol->isClassBounded())
+        error = diag::objc_protocol_not_class_protocol;
+    } else {
+      error = diag::invalid_objc_decl;
     }
-    if (!isLegal) {
-      TC.diagnose(VD->getStartLoc(), diag::invalid_objc_decl);
+    
+    if (error) {
+      TC.diagnose(VD->getStartLoc(), *error);
       VD->getMutableAttrs().ObjC = false;
       return;
     }