Fix a mangling bug where functions with no arguments weren't getting the 'v' parameter specifier.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@68162 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/Mangle.cpp b/lib/CodeGen/Mangle.cpp
index 7a7a480..427cc76 100644
--- a/lib/CodeGen/Mangle.cpp
+++ b/lib/CodeGen/Mangle.cpp
@@ -477,6 +477,11 @@
   const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(T);
   assert(Proto && "Can't mangle K&R function prototypes");
 
+  if (Proto->getNumArgs() == 0) {
+    Out << 'v';
+    return;
+  }
+    
   for (FunctionProtoType::arg_type_iterator Arg = Proto->arg_type_begin(),
                                          ArgEnd = Proto->arg_type_end(); 
        Arg != ArgEnd; ++Arg)
diff --git a/test/CodeGenCXX/mangle.cpp b/test/CodeGenCXX/mangle.cpp
index 855a2ae..7acb31c 100644
--- a/test/CodeGenCXX/mangle.cpp
+++ b/test/CodeGenCXX/mangle.cpp
@@ -24,3 +24,5 @@
 typedef struct { int a; } x,y;
 void f(y) { }
 
+// RUN: grep _Z1fv %t | count 1
+void f() { }