Fix compilation problem introduced in r308433

llvm-svn: 308438
diff --git a/clang/lib/Sema/SemaCodeComplete.cpp b/clang/lib/Sema/SemaCodeComplete.cpp
index f4f42e8..91a8c61 100644
--- a/clang/lib/Sema/SemaCodeComplete.cpp
+++ b/clang/lib/Sema/SemaCodeComplete.cpp
@@ -2418,7 +2418,7 @@
     // This happens if the code is incorrect (for example class is forward declared).
     return "";
   }
-  std::string DefValue{srcText};
+  std::string DefValue(srcText.str());
   // FIXME: remove this check if the Lexer::getSourceText value is fixed and
   // this value always has (or always does not have) '=' in front of it
   if (DefValue.at(0) != '=') {