Try fixing MSVC build after r223802

LLVM_EXPLICIT is only supported by recent version of MSVC, and it seems
the not-so-recent versions get confused about the operator bool() when
tryint to resolve operator== calls.

This removed the operator bool()'s since they don't seem to be used
anyway.

llvm-svn: 223824

llvm/include/llvm/IR/Metadata.h

@@ -525,7 +525,6 @@ public:
   MDOperand() : MD(nullptr) {}
   ~MDOperand() { untrack(); }
 
-  LLVM_EXPLICIT operator bool() const { return get(); }
   Metadata *get() const { return MD; }
   operator Metadata *() const { return get(); }
   Metadata *operator->() const { return get(); }

llvm/include/llvm/IR/TrackingMDRef.h

@@ -55,7 +55,6 @@ public:
   }
   ~TrackingMDRef() { untrack(); }
 
-  LLVM_EXPLICIT operator bool() const { return get(); }
   Metadata *get() const { return MD; }
   operator Metadata *() const { return get(); }
   Metadata *operator->() const { return get(); }
@@ -121,7 +120,6 @@ public:
     return *this;
   }
 
-  LLVM_EXPLICIT operator bool() const { return get(); }
   T *get() const { return (T *)Ref.get(); }
   operator T *() const { return get(); }
   T *operator->() const { return get(); }

llvm/lib/IR/DebugInfo.cpp

@@ -662,7 +662,7 @@ static void VerifySubsetOf(const MDNode *LHS, const MDNode *RHS) {
     const MDNode *E = cast<MDNode>(LHS->getOperand(i));
     bool found = false;
     for (unsigned j = 0; !found && j != RHS->getNumOperands(); ++j)
-      found = E == RHS->getOperand(j);
+      found = (E == cast<MDNode>(RHS->getOperand(j)));
     assert(found && "Losing a member during member list replacement");
   }
 }