Allow redeclaration of typedefs in C++

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@59822 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 20 insertions, 1 deletions

diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 7408507f23..0b05177dd3 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -344,7 +344,14 @@ TypedefDecl *Sema::MergeTypeDefDecl(TypedefDecl *New, Decl *OldD) {
   
   if (getLangOptions().Microsoft) return New;
 
-  // Redeclaration of a type is a constraint violation (6.7.2.3p1).
+  // C++ [dcl.typedef]p2:
+  //   In a given non-class scope, a typedef specifier can be used to
+  //   redefine the name of any type declared in that scope to refer
+  //   to the type to which it already refers.
+  if (getLangOptions().CPlusPlus && !isa<CXXRecordDecl>(CurContext))
+    return New;
+
+  // In C, redeclaration of a type is a constraint violation (6.7.2.3p1).
   // Apparently GCC, Intel, and Sun all silently ignore the redeclaration if
   // *either* declaration is in a system header. The code below implements
   // this adhoc compatibility rule. FIXME: The following code will not
diff --git a/test/SemaCXX/typedef-redecl.cpp b/test/SemaCXX/typedef-redecl.cpp
new file mode 100644
index 0000000000..c37a08ab3a
--- /dev/null
+++ b/test/SemaCXX/typedef-redecl.cpp
@@ -0,0 +1,12 @@
+// RUN: clang -fsyntax-only -verify %s 
+
+typedef int INT;
+typedef INT REALLY_INT; // expected-error{{previous definition is here}}
+typedef REALLY_INT REALLY_REALLY_INT;
+typedef REALLY_INT BOB;
+typedef float REALLY_INT; // expected-error{{typedef redefinition with different types ('float' vs 'INT')}}
+
+class X {
+  typedef int result_type; // expected-error{{previous definition is here}}
+  typedef INT result_type; // expected-error{{redefinition of 'result_type'}}
+};