Use only explicit bool conversion operators

BitVector/SmallBitVector::reference::operator bool remain implicit since
they model more exactly a bool, rather than something else that can be
boolean tested.

The most common (non-buggy) case are where such objects are used as
return expressions in bool-returning functions or as boolean function
arguments. In those cases I've used (& added if necessary) a named
function to provide the equivalent (or sometimes negative, depending on
convenient wording) test.

One behavior change (YAMLParser) was made, though no test case is
included as I'm not sure how to reach that code path. Essentially any
comparison of llvm::yaml::document_iterators would be invalid if neither
iterator was at the end.

This helped uncover a couple of bugs in Clang - test cases provided for
those in a separate commit along with similar changes to `operator bool`
instances in Clang.

llvm-svn: 181868

13 files changed, 23 insertions, 17 deletions

diff --git a/llvm/include/llvm/ADT/IntervalMap.h b/llvm/include/llvm/ADT/IntervalMap.h
index c4083eed6a9..44a61fff851 100644
--- a/llvm/include/llvm/ADT/IntervalMap.h
+++ b/llvm/include/llvm/ADT/IntervalMap.h
@@ -496,7 +496,7 @@ public:
   NodeRef() {}
 
   /// operator bool - Detect a null ref.
-  operator bool() const { return pip.getOpaqueValue(); }
+  LLVM_EXPLICIT operator bool() const { return pip.getOpaqueValue(); }
 
   /// NodeRef - Create a reference to the node p with n elements.
   template <typename NodeT>
diff --git a/llvm/include/llvm/ADT/OwningPtr.h b/llvm/include/llvm/ADT/OwningPtr.h
index 86f9feee2cb..6b9e42eaec0 100644
--- a/llvm/include/llvm/ADT/OwningPtr.h
+++ b/llvm/include/llvm/ADT/OwningPtr.h
@@ -70,8 +70,9 @@ public:
 
   T *operator->() const { return Ptr; }
   T *get() const { return Ptr; }
-  operator bool() const { return Ptr != 0; }
+  LLVM_EXPLICIT operator bool() const { return Ptr != 0; }
   bool operator!() const { return Ptr == 0; }
+  bool isValid() const { return Ptr != 0; }
 
   void swap(OwningPtr &RHS) {
     T *Tmp = RHS.Ptr;
@@ -132,7 +133,7 @@ public:
   }
 
   T *get() const { return Ptr; }
-  operator bool() const { return Ptr != 0; }
+  LLVM_EXPLICIT operator bool() const { return Ptr != 0; }
   bool operator!() const { return Ptr == 0; }
 
   void swap(OwningArrayPtr &RHS) {
diff --git a/llvm/include/llvm/ADT/PointerUnion.h b/llvm/include/llvm/ADT/PointerUnion.h
index f42515ac77a..b63ee52cddd 100644
--- a/llvm/include/llvm/ADT/PointerUnion.h
+++ b/llvm/include/llvm/ADT/PointerUnion.h
@@ -109,7 +109,7 @@ namespace llvm {
       // we recursively strip off low bits if we have a nested PointerUnion.
       return !PointerLikeTypeTraits<PT1>::getFromVoidPointer(Val.getPointer());
     }
-    operator bool() const { return !isNull(); }
+    LLVM_EXPLICIT operator bool() const { return !isNull(); }
 
     /// is<T>() return true if the Union currently holds the type matching T.
     template<typename T>
@@ -174,6 +174,11 @@ namespace llvm {
       return V;
     }
   };
+
+  template<typename PT1, typename PT2>
+  bool operator==(PointerUnion<PT1, PT2> lhs, PointerUnion<PT1, PT2> rhs) {
+    return lhs.getOpaqueValue() == rhs.getOpaqueValue();
+  }
   
   // Teach SmallPtrSet that PointerUnion is "basically a pointer", that has
   // # low bits available = min(PT1bits,PT2bits)-1.
@@ -251,7 +256,7 @@ namespace llvm {
     /// isNull - Return true if the pointer held in the union is null,
     /// regardless of which type it is.
     bool isNull() const { return Val.isNull(); }
-    operator bool() const { return !isNull(); }
+    LLVM_EXPLICIT operator bool() const { return !isNull(); }
     
     /// is<T>() return true if the Union currently holds the type matching T.
     template<typename T>
@@ -359,7 +364,7 @@ namespace llvm {
     /// isNull - Return true if the pointer held in the union is null,
     /// regardless of which type it is.
     bool isNull() const { return Val.isNull(); }
-    operator bool() const { return !isNull(); }
+    LLVM_EXPLICIT operator bool() const { return !isNull(); }
     
     /// is<T>() return true if the Union currently holds the type matching T.
     template<typename T>
diff --git a/llvm/include/llvm/Analysis/InlineCost.h b/llvm/include/llvm/Analysis/InlineCost.h
index bc7924e10fd..28baa9eb94c 100644
--- a/llvm/include/llvm/Analysis/InlineCost.h
+++ b/llvm/include/llvm/Analysis/InlineCost.h
@@ -77,7 +77,7 @@ public:
   }
 
   /// \brief Test whether the inline cost is low enough for inlining.
-  operator bool() const {
+  LLVM_EXPLICIT operator bool() const {
     return Cost < Threshold;
   }
 
diff --git a/llvm/include/llvm/CodeGen/SlotIndexes.h b/llvm/include/llvm/CodeGen/SlotIndexes.h
index 26d0433f3e8..676cdaf7fbf 100644
--- a/llvm/include/llvm/CodeGen/SlotIndexes.h
+++ b/llvm/include/llvm/CodeGen/SlotIndexes.h
@@ -162,7 +162,7 @@ namespace llvm {
     }
 
     /// Return true for a valid index.
-    operator bool() const { return isValid(); }
+    LLVM_EXPLICIT operator bool() const { return isValid(); }
 
     /// Print this index to the given raw_ostream.
     void print(raw_ostream &os) const;
diff --git a/llvm/include/llvm/Support/CallSite.h b/llvm/include/llvm/Support/CallSite.h
index 92107ac0252..d80d9d8ad15 100644
--- a/llvm/include/llvm/Support/CallSite.h
+++ b/llvm/include/llvm/Support/CallSite.h
@@ -78,7 +78,7 @@ public:
 
   InstrTy *getInstruction() const { return I.getPointer(); }
   InstrTy *operator->() const { return I.getPointer(); }
-  operator bool() const { return I.getPointer(); }
+  LLVM_EXPLICIT operator bool() const { return I.getPointer(); }
 
   /// getCalledValue - Return the pointer to function that is being called.
   ///
diff --git a/llvm/include/llvm/Support/YAMLParser.h b/llvm/include/llvm/Support/YAMLParser.h
index 6e4f57f6ab4..338bb4b6f2b 100644
--- a/llvm/include/llvm/Support/YAMLParser.h
+++ b/llvm/include/llvm/Support/YAMLParser.h
@@ -516,7 +516,7 @@ public:
     if (isAtEnd() || Other.isAtEnd())
       return isAtEnd() && Other.isAtEnd();
 
-    return *Doc == *Other.Doc;
+    return Doc == Other.Doc;
   }
   bool operator !=(const document_iterator &Other) {
     return !(*this == Other);
@@ -543,7 +543,7 @@ public:
 
 private:
   bool isAtEnd() const {
-    return Doc == 0 || *Doc == 0;
+    return !Doc || !*Doc;
   }
 
   OwningPtr<Document> *Doc;
diff --git a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
index c0009cb9899..674ce3aea71 100644
--- a/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/llvm/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -89,7 +89,7 @@ bool MemoryDependenceAnalysis::runOnFunction(Function &) {
   AA = &getAnalysis<AliasAnalysis>();
   TD = getAnalysisIfAvailable<DataLayout>();
   DT = getAnalysisIfAvailable<DominatorTree>();
-  if (PredCache == 0)
+  if (!PredCache)
     PredCache.reset(new PredIteratorCache());
   return false;
 }
diff --git a/llvm/lib/CodeGen/RegAllocGreedy.cpp b/llvm/lib/CodeGen/RegAllocGreedy.cpp
index 9eed1fc62ac..49748289dac 100644
--- a/llvm/lib/CodeGen/RegAllocGreedy.cpp
+++ b/llvm/lib/CodeGen/RegAllocGreedy.cpp
@@ -713,7 +713,7 @@ bool RAGreedy::addSplitConstraints(InterferenceCache::Cursor Intf,
     Intf.moveToBlock(BC.Number);
     BC.Entry = BI.LiveIn ? SpillPlacement::PrefReg : SpillPlacement::DontCare;
     BC.Exit = BI.LiveOut ? SpillPlacement::PrefReg : SpillPlacement::DontCare;
-    BC.ChangesValue = BI.FirstDef;
+    BC.ChangesValue = BI.FirstDef.isValid();
 
     if (!Intf.hasInterference())
       continue;
diff --git a/llvm/lib/Support/SourceMgr.cpp b/llvm/lib/Support/SourceMgr.cpp
index fac3cad5cc2..4f650b42cce 100644
--- a/llvm/lib/Support/SourceMgr.cpp
+++ b/llvm/lib/Support/SourceMgr.cpp
@@ -65,7 +65,7 @@ unsigned SourceMgr::AddIncludeFile(const std::string &Filename,
     MemoryBuffer::getFile(IncludedFile.c_str(), NewBuf);
   }
 
-  if (NewBuf == 0) return ~0U;
+  if (!NewBuf) return ~0U;
 
   return AddNewSourceBuffer(NewBuf.take(), IncludeLoc);
 }
diff --git a/llvm/lib/Support/Windows/Windows.h b/llvm/lib/Support/Windows/Windows.h
index 5c1da0d617a..2ddd15efa19 100644
--- a/llvm/lib/Support/Windows/Windows.h
+++ b/llvm/lib/Support/Windows/Windows.h
@@ -75,7 +75,7 @@ public:
   }
 
   // True if Handle is valid.
-  operator bool() const {
+  LLVM_EXPLICIT operator bool() const {
     return HandleTraits::IsValid(Handle) ? true : false;
   }
 
diff --git a/llvm/tools/bugpoint/Miscompilation.cpp b/llvm/tools/bugpoint/Miscompilation.cpp
index c676a05cb6c..11ac0de104e 100644
--- a/llvm/tools/bugpoint/Miscompilation.cpp
+++ b/llvm/tools/bugpoint/Miscompilation.cpp
@@ -130,7 +130,7 @@ ReduceMiscompilingPasses::doTest(std::vector<std::string> &Prefix,
   //
   OwningPtr<Module> PrefixOutput(ParseInputFile(BitcodeResult,
                                                 BD.getContext()));
-  if (PrefixOutput == 0) {
+  if (!PrefixOutput) {
     errs() << BD.getToolName() << ": Error reading bitcode file '"
            << BitcodeResult << "'!\n";
     exit(1);
diff --git a/llvm/unittests/ExecutionEngine/MCJIT/MCJITObjectCacheTest.cpp b/llvm/unittests/ExecutionEngine/MCJIT/MCJITObjectCacheTest.cpp
index 0061e30e7a5..abe8be450ae 100644
--- a/llvm/unittests/ExecutionEngine/MCJIT/MCJITObjectCacheTest.cpp
+++ b/llvm/unittests/ExecutionEngine/MCJIT/MCJITObjectCacheTest.cpp
@@ -98,7 +98,7 @@ protected:
 
   void compileAndRun(int ExpectedRC = OriginalRC) {
     // This function shouldn't be called until after SetUp.
-    ASSERT_TRUE(0 != TheJIT);
+    ASSERT_TRUE(TheJIT.isValid());
     ASSERT_TRUE(0 != Main);
 
     TheJIT->finalizeObject();