Always allow redefinition of typedefs when modules are enabled. This

is important because it's fairly common for headers (especially system
headers) to want to provide only those typedefs needed for that
particular header, based on some guard macro, e.g.,

#ifndef _SIZE_T
#define _SIZE_T
typedef long size_t;
#endif

which is repeated in a number of headers. The guard macro protects
against duplicate definitions. However, this means that only the first
occurrence of this pattern actually defines size_t, so the submodule
corresponding to this header has the only visible definition. If a
user then imports a different submodule from the same module, size_t
will be known but not visible, and therefore cannot be used.

By allowing redefinition of typedefs, each header that wants to define
size_t can do so independently, so it will be available in the
corresponding submodules.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@147775 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 54f953d343712f1c45b919e2924a57cddfb7f47e..b541e7d9e717a47b3763aa5e8757e8958b796470 100644 (file)
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -1509,6 +1509,10 @@ void Sema::MergeTypedefNameDecl(TypedefNameDecl *New, LookupResult &OldDecls) {
     return New->setInvalidDecl();
   }
 
+  // Modules always permit redefinition of typedefs.
+  if (getLangOptions().Modules)
+    return;
+  
   // If we have a redefinition of a typedef in C, emit a warning.  This warning
   // is normally mapped to an error, but can be controlled with
   // -Wtypedef-redefinition.  If either the original or the redefinition is

diff --git a/test/Modules/redecl-merge.m b/test/Modules/redecl-merge.m
index 09898a5b3b8a6728d582660b390eb1195ab491c5..e6de22a85aa06ebc709de13acdc4d9dd6355a813 100644 (file)
--- a/test/Modules/redecl-merge.m
+++ b/test/Modules/redecl-merge.m
@@ -1,5 +1,5 @@
 // RUN: rm -rf %t
-// RUN: %clang_cc1 -fmodules -fmodule-cache-path %t -Wno-typedef-redefinition -I %S/Inputs %s -verify
+// RUN: %clang_cc1 -fmodules -fmodule-cache-path %t -I %S/Inputs %s -verify
 // RUN: %clang_cc1 -x objective-c++ -fmodules -fmodule-cache-path %t -I %S/Inputs %s -verify
 @class C2;
 @class C3;