From 7dcf23ed83d0094386aa438db3b47ec0aacf149d Mon Sep 17 00:00:00 2001
From: Bruno Cardoso Lopes <bruno.cardoso@gmail.com>
Date: Sat, 30 Jun 2018 00:49:27 +0000
Subject: [PATCH] Add protocol redefinition to the current scope/context

Not doing so causes the AST writter to assert since the decl in question
never gets emitted. This is fine when modules is not used, but otherwise
we need to serialize something other than garbage.

rdar://problem/39844933

Differential Revision: https://reviews.llvm.org/D47297

llvm-svn: 336031
---
 clang/lib/Sema/SemaDeclObjC.cpp                             | 5 +++++
 .../protocol-redefinition/Base.framework/Headers/Base.h     | 3 +++
 .../Base.framework/Modules/module.modulemap                 | 4 ++++
 .../protocol-redefinition/Kit.framework/Headers/Kit.h       | 6 ++++++
 .../Kit.framework/Modules/module.modulemap                  | 4 ++++
 clang/test/Modules/protocol-redefinition.m                  | 6 ++++++
 6 files changed, 28 insertions(+)
 create mode 100644 clang/test/Modules/Inputs/protocol-redefinition/Base.framework/Headers/Base.h
 create mode 100644 clang/test/Modules/Inputs/protocol-redefinition/Base.framework/Modules/module.modulemap
 create mode 100644 clang/test/Modules/Inputs/protocol-redefinition/Kit.framework/Headers/Kit.h
 create mode 100644 clang/test/Modules/Inputs/protocol-redefinition/Kit.framework/Modules/module.modulemap
 create mode 100644 clang/test/Modules/protocol-redefinition.m

diff --git a/clang/lib/Sema/SemaDeclObjC.cpp b/clang/lib/Sema/SemaDeclObjC.cpp
index d7544ecfaf79c..6809b48dc8a48 100644
--- a/clang/lib/Sema/SemaDeclObjC.cpp
+++ b/clang/lib/Sema/SemaDeclObjC.cpp
@@ -1210,6 +1210,11 @@ Sema::ActOnStartProtocolInterface(SourceLocation AtProtoInterfaceLoc,
     PDecl = ObjCProtocolDecl::Create(Context, CurContext, ProtocolName,
                                      ProtocolLoc, AtProtoInterfaceLoc,
                                      /*PrevDecl=*/nullptr);
+
+    // If we are using modules, add the decl to the context in order to
+    // serialize something meaningful.
+    if (getLangOpts().Modules)
+      PushOnScopeChains(PDecl, TUScope);
     PDecl->startDefinition();
   } else {
     if (PrevDecl) {
diff --git a/clang/test/Modules/Inputs/protocol-redefinition/Base.framework/Headers/Base.h b/clang/test/Modules/Inputs/protocol-redefinition/Base.framework/Headers/Base.h
new file mode 100644
index 0000000000000..e3fe33c1bdb91
--- /dev/null
+++ b/clang/test/Modules/Inputs/protocol-redefinition/Base.framework/Headers/Base.h
@@ -0,0 +1,3 @@
+@protocol Foo
+- (void)someMethodOnFoo;
+@end
diff --git a/clang/test/Modules/Inputs/protocol-redefinition/Base.framework/Modules/module.modulemap b/clang/test/Modules/Inputs/protocol-redefinition/Base.framework/Modules/module.modulemap
new file mode 100644
index 0000000000000..0366bb4f03903
--- /dev/null
+++ b/clang/test/Modules/Inputs/protocol-redefinition/Base.framework/Modules/module.modulemap
@@ -0,0 +1,4 @@
+framework module Base {
+  header "Base.h"
+  export *
+}
\ No newline at end of file
diff --git a/clang/test/Modules/Inputs/protocol-redefinition/Kit.framework/Headers/Kit.h b/clang/test/Modules/Inputs/protocol-redefinition/Kit.framework/Headers/Kit.h
new file mode 100644
index 0000000000000..93384c294f135
--- /dev/null
+++ b/clang/test/Modules/Inputs/protocol-redefinition/Kit.framework/Headers/Kit.h
@@ -0,0 +1,6 @@
+#import <Base/Base.h>
+
+// REDECLARATION
+@protocol Foo
+- (void)someMethodOnFoo;
+@end
diff --git a/clang/test/Modules/Inputs/protocol-redefinition/Kit.framework/Modules/module.modulemap b/clang/test/Modules/Inputs/protocol-redefinition/Kit.framework/Modules/module.modulemap
new file mode 100644
index 0000000000000..2b790f4496549
--- /dev/null
+++ b/clang/test/Modules/Inputs/protocol-redefinition/Kit.framework/Modules/module.modulemap
@@ -0,0 +1,4 @@
+framework module Kit {
+  header "Kit.h"
+  export *
+}
\ No newline at end of file
diff --git a/clang/test/Modules/protocol-redefinition.m b/clang/test/Modules/protocol-redefinition.m
new file mode 100644
index 0000000000000..85a957bbfd70a
--- /dev/null
+++ b/clang/test/Modules/protocol-redefinition.m
@@ -0,0 +1,6 @@
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t -F%S/Inputs/protocol-redefinition -fsyntax-only %s -Wno-private-module -verify
+
+// expected-no-diagnostics
+
+@import Kit;