Add explicit keywords.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@48801 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/TableGen/DAGISelEmitter.cpp b/utils/TableGen/DAGISelEmitter.cpp
index dc95e79..70d88ce 100644
--- a/utils/TableGen/DAGISelEmitter.cpp
+++ b/utils/TableGen/DAGISelEmitter.cpp
@@ -2072,7 +2072,7 @@
   OS << "    std::vector<SDNode*> &ISelQueue;\n";
   OS << "    bool HadDelete;\n";
   OS << "  public:\n";
-  OS << "    ISelQueueUpdater(std::vector<SDNode*> &isq)\n";
+  OS << "    explicit ISelQueueUpdater(std::vector<SDNode*> &isq)\n";
   OS << "      : ISelQueue(isq), HadDelete(false) {}\n";
   OS << "    \n";
   OS << "    bool hadDelete() const { return HadDelete; }\n";