explicit keywords.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42262 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/GVNPRE.cpp b/lib/Transforms/Scalar/GVNPRE.cpp
index b3d2fe2..b164873 100644
--- a/lib/Transforms/Scalar/GVNPRE.cpp
+++ b/lib/Transforms/Scalar/GVNPRE.cpp
@@ -70,7 +70,7 @@
   SmallVector<uint32_t, 4> varargs;
   
   Expression() { }
-  Expression(ExpressionOpcode o) : opcode(o) { }
+  explicit Expression(ExpressionOpcode o) : opcode(o) { }
   
   bool operator==(const Expression &other) const {
     if (opcode != other.opcode)