2 files changed, 13 insertions, 7 deletions
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index 4d7310a146e..32284968c90 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -9389,6 +9389,19 @@ FinishedParams:
     return true;
   }
 
+  // A parameter-declaration-clause containing a default argument is not
+  // equivalent to any of the permitted forms.
+  for (FunctionDecl::param_iterator Param = FnDecl->param_begin(),
+                                    ParamEnd = FnDecl->param_end();
+       Param != ParamEnd; ++Param) {
+    if ((*Param)->hasDefaultArg()) {
+      Diag((*Param)->getDefaultArgRange().getBegin(),
+           diag::err_literal_operator_default_argument)
+        << (*Param)->getDefaultArgRange();
+      break;
+    }
+  }
+
   StringRef LiteralName
     = FnDecl->getDeclName().getCXXLiteralIdentifier()->getName();
   if (LiteralName[0] != '_') {
diff --git a/clang/lib/Sema/SemaOverload.cpp b/clang/lib/Sema/SemaOverload.cpp
index e74e6d5e126..fac3b7f3839 100644
--- a/clang/lib/Sema/SemaOverload.cpp
+++ b/clang/lib/Sema/SemaOverload.cpp
@@ -10911,13 +10911,6 @@ ExprResult Sema::BuildLiteralOperatorCall(LookupResult &R,
 
   bool HadMultipleCandidates = (CandidateSet.size() > 1);
 
-  // FIXME: Reject default arguments in literal operator definitions. We're not
-  // supposed to treat this as ambiguous:
-  //
-  //   int operator"" _x(const char *p);
-  //   int operator"" _x(const char *p, size_t n = 0);
-  //   int k = 123_x;
-
   // Perform overload resolution. This will usually be trivial, but might need
   // to perform substitutions for a literal operator template.
   OverloadCandidateSet::iterator Best;