Make llvm::function_ref's operator bool explicit

This can avoid all sorts of mistakes with implicit conversion
(indirectly) to int, etc. I'm quite surprise there aren't any things to
fixup with this - but I guess most uses of function_ref aren't
optional/nullable.

diff --git a/llvm/include/llvm/ADT/STLExtras.h b/llvm/include/llvm/ADT/STLExtras.h
index 638895e..ad1150b 100644 (file)
--- a/llvm/include/llvm/ADT/STLExtras.h
+++ b/llvm/include/llvm/ADT/STLExtras.h
@@ -124,7 +124,7 @@ public:
     return callback(callable, std::forward<Params>(params)...);
   }
 
-  operator bool() const { return callback; }
+  explicit operator bool() const { return callback; }
 };
 
 // deleter - Very very very simple method that is used to invoke operator