Fixed failing assert in code completion.

Summary:
The code was accessing uninstantiated default argument.
This resulted in failing assertion at ParmVarDecl::getDefaultArg().

Reviewers: erikjv, klimek, bkramer, krasimir

Reviewed By: krasimir

Subscribers: cfe-commits

Differential Revision: https://reviews.llvm.org/D35682

llvm-svn: 308722
diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
index 91a8c61..4de7d42 100644
--- a/clang/lib/Sema/SemaCodeComplete.cpp
+++ b/clang/lib/Sema/SemaCodeComplete.cpp
@@ -2401,10 +2401,7 @@
 static std::string GetDefaultValueString(const ParmVarDecl *Param,
                                          const SourceManager &SM,
                                          const LangOptions &LangOpts) {
-  const Expr *defaultArg = Param->getDefaultArg();
-  if (!defaultArg)
-    return "";
-  const SourceRange SrcRange = defaultArg->getSourceRange();
+  const SourceRange SrcRange = Param->getDefaultArgRange();
   CharSourceRange CharSrcRange = CharSourceRange::getTokenRange(SrcRange);
   bool Invalid = CharSrcRange.isInvalid();
   if (Invalid)