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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181868 91177308-0d34-0410-b5e6-96231b3b80d8

13 files changed, 23 insertions, 17 deletions

diff --git a/include/llvm/ADT/IntervalMap.h b/include/llvm/ADT/IntervalMap.h
index c4083ee..44a61ff 100644
--- a/include/llvm/ADT/IntervalMap.h
+++ b/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/include/llvm/ADT/OwningPtr.h b/include/llvm/ADT/OwningPtr.h
index 86f9fee..6b9e42e 100644
--- a/include/llvm/ADT/OwningPtr.h
+++ b/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/include/llvm/ADT/PointerUnion.h b/include/llvm/ADT/PointerUnion.h
index f42515a..b63ee52 100644
--- a/include/llvm/ADT/PointerUnion.h
+++ b/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/include/llvm/Analysis/InlineCost.h b/include/llvm/Analysis/InlineCost.h
index bc7924e..28baa9e 100644
--- a/include/llvm/Analysis/InlineCost.h
+++ b/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/include/llvm/CodeGen/SlotIndexes.h b/include/llvm/CodeGen/SlotIndexes.h
index 26d0433..676cdaf 100644
--- a/include/llvm/CodeGen/SlotIndexes.h
+++ b/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/include/llvm/Support/CallSite.h b/include/llvm/Support/CallSite.h
index 92107ac..d80d9d8 100644
--- a/include/llvm/Support/CallSite.h
+++ b/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/include/llvm/Support/YAMLParser.h b/include/llvm/Support/YAMLParser.h
index 6e4f57f..338bb4b 100644
--- a/include/llvm/Support/YAMLParser.h
+++ b/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/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp
index c0009cb..674ce3a 100644
--- a/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/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/lib/CodeGen/RegAllocGreedy.cpp b/lib/CodeGen/RegAllocGreedy.cpp
index 9eed1fc..4974828 100644
--- a/lib/CodeGen/RegAllocGreedy.cpp
+++ b/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/lib/Support/SourceMgr.cpp b/lib/Support/SourceMgr.cpp
index fac3cad..4f650b4 100644
--- a/lib/Support/SourceMgr.cpp
+++ b/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/lib/Support/Windows/Windows.h b/lib/Support/Windows/Windows.h
index 5c1da0d..2ddd15e 100644
--- a/lib/Support/Windows/Windows.h
+++ b/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/tools/bugpoint/Miscompilation.cpp b/tools/bugpoint/Miscompilation.cpp
index c676a05..11ac0de 100644
--- a/tools/bugpoint/Miscompilation.cpp
+++ b/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/unittests/ExecutionEngine/MCJIT/MCJITObjectCacheTest.cpp b/unittests/ExecutionEngine/MCJIT/MCJITObjectCacheTest.cpp
index 0061e30..abe8be4 100644
--- a/unittests/ExecutionEngine/MCJIT/MCJITObjectCacheTest.cpp
+++ b/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();