Subzero: Improve class definition hygiene.

src/IceRegAlloc.h

 //===- subzero/src/IceRegAlloc.h - Linear-scan reg. allocation --*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file declares the LinearScan data structure used during
 // linear-scan register allocation, which holds the various work
 // queues for the linear-scan algorithm.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef SUBZERO_SRC_ICEREGALLOC_H
 #define SUBZERO_SRC_ICEREGALLOC_H
 
 #include "IceDefs.h"
 #include "IceTypes.h"
 
 namespace Ice {
 
 class LinearScan {
+  LinearScan() = delete;
   LinearScan(const LinearScan &) = delete;
   LinearScan &operator=(const LinearScan &) = delete;
 
 public:
-  LinearScan(Cfg *Func)
+  explicit LinearScan(Cfg *Func)
       : Func(Func), FindPreference(false), FindOverlap(false) {}
   void init(RegAllocKind Kind);
   void scan(const llvm::SmallBitVector &RegMask, bool Randomized);
   void dump(Cfg *Func) const;
 
 private:
   typedef std::vector<Variable *> OrderedRanges;
   typedef std::vector<Variable *> UnorderedRanges;
 
   void initForGlobal();
@@ skipping 21 matching lines @@
   bool FindOverlap;
   // TODO(stichnot): We're not really using FindOverlap yet, but we
   // may want a flavor of register allocation where FindPreference is
   // useful but we didn't want to initialize VMetadata with VMK_All
   // and therefore we can't safely allow overlap.
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEREGALLOC_H