Demangle Dc to decltype(auto) as per the Itanium C++ ABI spec.

git-svn-id: https://llvm.org/svn/llvm-project/libcxxabi/trunk@201533 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/src/cxa_demangle.cpp b/src/cxa_demangle.cpp
index 839aebe..d1661e8 100644
--- a/src/cxa_demangle.cpp
+++ b/src/cxa_demangle.cpp
@@ -352,6 +352,7 @@
 //                ::= Di   # char32_t
 //                ::= Ds   # char16_t
 //                ::= Da   # auto (in dependent new-expressions)
+//                ::= Dc   # decltype(auto)
 //                ::= Dn   # std::nullptr_t (i.e., decltype(nullptr))
 //                ::= u <source-name>    # vendor extended type
 
@@ -487,6 +488,10 @@
                     db.names.push_back("auto");
                     first += 2;
                     break;
+                case 'c':
+                    db.names.push_back("decltype(auto)");
+                    first += 2;
+                    break;
                 case 'n':
                     db.names.push_back("std::nullptr_t");
                     first += 2;
diff --git a/test/test_demangle.cpp b/test/test_demangle.cpp
index 2d9dd55..bb5b66d 100644
--- a/test/test_demangle.cpp
+++ b/test/test_demangle.cpp
@@ -29585,6 +29585,7 @@
     {"_ZNK1AIJ1Z1Y1XEEcv1BIJDpPT_EEIJS2_S1_S0_EEEv", "A<Z, Y, X>::operator B<X*, Y*, Z*><X, Y, Z>() const"},
     {"_ZNK3Ncr6Silver7Utility6detail12CallOnThreadIZ53-[DeploymentSetupController handleManualServerEntry:]E3$_5EclIJEEEDTclclL_ZNS2_4getTIS4_EERT_vEEspclsr3stdE7forwardIT_Efp_EEEDpOSA_", "decltype(-[DeploymentSetupController handleManualServerEntry:]::$_5& Ncr::Silver::Utility::detail::getT<-[DeploymentSetupController handleManualServerEntry:]::$_5>()()(std::forward<-[DeploymentSetupController handleManualServerEntry:]::$_5>(fp))) Ncr::Silver::Utility::detail::CallOnThread<-[DeploymentSetupController handleManualServerEntry:]::$_5>::operator()<>(-[DeploymentSetupController handleManualServerEntry:]::$_5&&) const"},
     {"_Zli2_xy", "operator\"\" _x(unsigned long long)"},
+    {"_Z1fIiEDcT_", "decltype(auto) f<int>(int)"},
 };
 
 const unsigned N = sizeof(cases) / sizeof(cases[0]);