Use only explicit bool conversion operator

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.

DiagnosticBuilder kept its implicit conversion operator owing to the
prevalent use of it in return statements.

One bug was found in ExprConstant.cpp involving a comparison of two
PointerUnions (PointerUnion did not previously have an operator==, so
instead both operands were converted to bool & then compared). A test
is included in test/SemaCXX/constant-expression-cxx1y.cpp for the fix
(adding operator== to PointerUnion in LLVM).

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@181869 91177308-0d34-0410-b5e6-96231b3b80d8

45 files changed, 71 insertions, 53 deletions

diff --git a/include/clang/AST/CanonicalType.h b/include/clang/AST/CanonicalType.h
index 946075739d..9c699b7e0a 100644
--- a/include/clang/AST/CanonicalType.h
+++ b/include/clang/AST/CanonicalType.h
@@ -81,7 +81,7 @@ public:
   operator QualType() const { return Stored; }
 
   /// \brief Implicit conversion to bool.
-  operator bool() const { return !isNull(); }
+  LLVM_EXPLICIT operator bool() const { return !isNull(); }
   
   bool isNull() const {
     return Stored.isNull();
diff --git a/include/clang/AST/DeclFriend.h b/include/clang/AST/DeclFriend.h
index 3a12878e74..589178ec6e 100644
--- a/include/clang/AST/DeclFriend.h
+++ b/include/clang/AST/DeclFriend.h
@@ -228,7 +228,7 @@ inline CXXRecordDecl::friend_iterator CXXRecordDecl::friend_end() const {
 }
 
 inline void CXXRecordDecl::pushFriendDecl(FriendDecl *FD) {
-  assert(FD->NextFriend == 0 && "friend already has next friend?");
+  assert(!FD->NextFriend && "friend already has next friend?");
   FD->NextFriend = data().FirstFriend;
   data().FirstFriend = FD;
 }
diff --git a/include/clang/AST/DeclObjC.h b/include/clang/AST/DeclObjC.h
index 40de0135a7..0028240349 100644
--- a/include/clang/AST/DeclObjC.h
+++ b/include/clang/AST/DeclObjC.h
@@ -452,7 +452,7 @@ public:
   }
 
   /// \brief Determine whether this method has a body.
-  virtual bool hasBody() const { return Body; }
+  virtual bool hasBody() const { return Body.isValid(); }
 
   /// \brief Retrieve the body of this method, if it has one.
   virtual Stmt *getBody() const;
@@ -463,7 +463,7 @@ public:
   void setBody(Stmt *B) { Body = B; }
 
   /// \brief Returns whether this specific method is a definition.
-  bool isThisDeclarationADefinition() const { return Body; }
+  bool isThisDeclarationADefinition() const { return hasBody(); }
 
   // Implement isa/cast/dyncast/etc.
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
diff --git a/include/clang/AST/DeclarationName.h b/include/clang/AST/DeclarationName.h
index e01b80f389..00766c27c1 100644
--- a/include/clang/AST/DeclarationName.h
+++ b/include/clang/AST/DeclarationName.h
@@ -182,11 +182,16 @@ public:
 
   // operator bool() - Evaluates true when this declaration name is
   // non-empty.
-  operator bool() const {
+  LLVM_EXPLICIT operator bool() const {
     return ((Ptr & PtrMask) != 0) ||
            (reinterpret_cast<IdentifierInfo *>(Ptr & ~PtrMask));
   }
 
+  /// \brief Evaluates true when this declaration name is empty.
+  bool isEmpty() const {
+    return !*this;
+  }
+
   /// Predicate functions for querying what type of name this is.
   bool isIdentifier() const { return getStoredNameKind() == StoredIdentifier; }
   bool isObjCZeroArgSelector() const {
diff --git a/include/clang/AST/ExprCXX.h b/include/clang/AST/ExprCXX.h
index 91e5b21eac..a4f296c988 100644
--- a/include/clang/AST/ExprCXX.h
+++ b/include/clang/AST/ExprCXX.h
@@ -1935,7 +1935,7 @@ public:
   /// \brief Determines whether this member expression actually had
   /// a C++ nested-name-specifier prior to the name of the member, e.g.,
   /// x->Base::foo.
-  bool hasQualifier() const { return QualifierLoc; }
+  bool hasQualifier() const { return QualifierLoc.hasQualifier(); }
 
   /// \brief Retrieves the nested-name-specifier that qualifies the type name,
   /// with source-location information.
diff --git a/include/clang/AST/ExternalASTSource.h b/include/clang/AST/ExternalASTSource.h
index 81fcf242b6..b077426e6a 100644
--- a/include/clang/AST/ExternalASTSource.h
+++ b/include/clang/AST/ExternalASTSource.h
@@ -329,7 +329,12 @@ public:
   /// \brief Whether this pointer is non-NULL.
   ///
   /// This operation does not require the AST node to be deserialized.
-  operator bool() const { return Ptr != 0; }
+  LLVM_EXPLICIT operator bool() const { return Ptr != 0; }
+
+  /// \brief Whether this pointer is non-NULL.
+  ///
+  /// This operation does not require the AST node to be deserialized.
+  bool isValid() const { return Ptr != 0; }
 
   /// \brief Whether this pointer is currently stored as an offset.
   bool isOffset() const { return Ptr & 0x01; }
diff --git a/include/clang/AST/NestedNameSpecifier.h b/include/clang/AST/NestedNameSpecifier.h
index 58f39862b1..b332b153fe 100644
--- a/include/clang/AST/NestedNameSpecifier.h
+++ b/include/clang/AST/NestedNameSpecifier.h
@@ -231,7 +231,11 @@ public:
 
   /// \brief Evalutes true when this nested-name-specifier location is
   /// non-empty.
-  operator bool() const { return Qualifier; }
+  LLVM_EXPLICIT operator bool() const { return Qualifier; }
+
+  /// \brief Evalutes true when this nested-name-specifier location is
+  /// empty.
+  bool hasQualifier() const { return Qualifier; }
 
   /// \brief Retrieve the nested-name-specifier to which this instance
   /// refers.
diff --git a/include/clang/AST/StmtIterator.h b/include/clang/AST/StmtIterator.h
index b933ed0762..fc25fa9a6e 100644
--- a/include/clang/AST/StmtIterator.h
+++ b/include/clang/AST/StmtIterator.h
@@ -15,6 +15,7 @@
 #define LLVM_CLANG_AST_STMT_ITR_H
 
 #include "llvm/Support/DataTypes.h"
+#include "llvm/Support/Compiler.h"
 #include <cassert>
 #include <cstddef>
 #include <iterator>
@@ -156,7 +157,7 @@ struct StmtRange : std::pair<StmtIterator,StmtIterator> {
     : std::pair<StmtIterator,StmtIterator>(begin, end) {}
 
   bool empty() const { return first == second; }
-  operator bool() const { return !empty(); }
+  LLVM_EXPLICIT operator bool() const { return !empty(); }
 
   Stmt *operator->() const { return first.operator->(); }
   Stmt *&operator*() const { return first.operator*(); }
@@ -199,7 +200,7 @@ struct ConstStmtRange : std::pair<ConstStmtIterator,ConstStmtIterator> {
     : std::pair<ConstStmtIterator,ConstStmtIterator>(begin, end) {}
 
   bool empty() const { return first == second; }
-  operator bool() const { return !empty(); }
+  LLVM_EXPLICIT operator bool() const { return !empty(); }
 
   const Stmt *operator->() const { return first.operator->(); }
   const Stmt *operator*() const { return first.operator*(); }
diff --git a/include/clang/AST/Type.h b/include/clang/AST/Type.h
index 39f10d3393..93c287fd18 100644
--- a/include/clang/AST/Type.h
+++ b/include/clang/AST/Type.h
@@ -441,7 +441,7 @@ public:
   bool operator==(Qualifiers Other) const { return Mask == Other.Mask; }
   bool operator!=(Qualifiers Other) const { return Mask != Other.Mask; }
 
-  operator bool() const { return hasQualifiers(); }
+  LLVM_EXPLICIT operator bool() const { return hasQualifiers(); }
 
   Qualifiers &operator+=(Qualifiers R) {
     addQualifiers(R);
diff --git a/include/clang/AST/TypeLoc.h b/include/clang/AST/TypeLoc.h
index 11cad9bb9d..9e2d3bffb9 100644
--- a/include/clang/AST/TypeLoc.h
+++ b/include/clang/AST/TypeLoc.h
@@ -90,7 +90,7 @@ public:
   }
 
   bool isNull() const { return !Ty; }
-  operator bool() const { return Ty; }
+  LLVM_EXPLICIT operator bool() const { return Ty; }
 
   /// \brief Returns the size of type source info data block for the given type.
   static unsigned getFullDataSizeForType(QualType Ty);
diff --git a/include/clang/Analysis/Analyses/FormatString.h b/include/clang/Analysis/Analyses/FormatString.h
index 4bd989cf4e..6ad89aec0a 100644
--- a/include/clang/Analysis/Analyses/FormatString.h
+++ b/include/clang/Analysis/Analyses/FormatString.h
@@ -49,7 +49,7 @@ public:
   const char *toString() const { return representation; }
 
   // Overloaded operators for bool like qualities
-  operator bool() const { return flag; }
+  LLVM_EXPLICIT operator bool() const { return flag; }
   OptionalFlag& operator=(const bool &rhs) {
     flag = rhs;
     return *this;  // Return a reference to myself.
diff --git a/include/clang/Analysis/CFG.h b/include/clang/Analysis/CFG.h
index ee0be736dd..01480ed3b4 100644
--- a/include/clang/Analysis/CFG.h
+++ b/include/clang/Analysis/CFG.h
@@ -269,7 +269,7 @@ public:
   Stmt &operator*() { return *getStmt(); }
   const Stmt &operator*() const { return *getStmt(); }
 
-  operator bool() const { return getStmt(); }
+  LLVM_EXPLICIT operator bool() const { return getStmt(); }
 };
 
 /// CFGBlock - Represents a single basic block in a source-level CFG.
diff --git a/include/clang/Basic/Diagnostic.h b/include/clang/Basic/Diagnostic.h
index 3e125944a3..1354120ea5 100644
--- a/include/clang/Basic/Diagnostic.h
+++ b/include/clang/Basic/Diagnostic.h
@@ -1212,7 +1212,7 @@ public:
   ~StoredDiagnostic();
 
   /// \brief Evaluates true when this object stores a diagnostic.
-  operator bool() const { return Message.size() > 0; }
+  LLVM_EXPLICIT operator bool() const { return Message.size() > 0; }
 
   unsigned getID() const { return ID; }
   DiagnosticsEngine::Level getLevel() const { return Level; }
diff --git a/include/clang/Frontend/ASTUnit.h b/include/clang/Frontend/ASTUnit.h
index 9bd0ef31e0..1fc56ce5f3 100644
--- a/include/clang/Frontend/ASTUnit.h
+++ b/include/clang/Frontend/ASTUnit.h
@@ -456,7 +456,7 @@ public:
   void setASTContext(ASTContext *ctx) { Ctx = ctx; }
   void setPreprocessor(Preprocessor *pp);
 
-  bool hasSema() const { return TheSema; }
+  bool hasSema() const { return TheSema.isValid(); }
   Sema &getSema() const { 
     assert(TheSema && "ASTUnit does not have a Sema object!");
     return *TheSema; 
diff --git a/include/clang/Frontend/CompilerInstance.h b/include/clang/Frontend/CompilerInstance.h
index dbd76066b9..ee4850580d 100644
--- a/include/clang/Frontend/CompilerInstance.h
+++ b/include/clang/Frontend/CompilerInstance.h
@@ -395,7 +395,7 @@ public:
   /// @name ASTConsumer
   /// {
 
-  bool hasASTConsumer() const { return Consumer != 0; }
+  bool hasASTConsumer() const { return Consumer.isValid(); }
 
   ASTConsumer &getASTConsumer() const {
     assert(Consumer && "Compiler instance has no AST consumer!");
@@ -413,7 +413,7 @@ public:
   /// }
   /// @name Semantic analysis
   /// {
-  bool hasSema() const { return TheSema != 0; }
+  bool hasSema() const { return TheSema.isValid(); }
   
   Sema &getSema() const { 
     assert(TheSema && "Compiler instance has no Sema object!");
@@ -433,7 +433,9 @@ public:
   /// @name Code Completion
   /// {
 
-  bool hasCodeCompletionConsumer() const { return CompletionConsumer != 0; }
+  bool hasCodeCompletionConsumer() const {
+    return CompletionConsumer.isValid();
+  }
 
   CodeCompleteConsumer &getCodeCompletionConsumer() const {
     assert(CompletionConsumer &&
@@ -455,7 +457,7 @@ public:
   /// @name Frontend timer
   /// {
 
-  bool hasFrontendTimer() const { return FrontendTimer != 0; }
+  bool hasFrontendTimer() const { return FrontendTimer.isValid(); }
 
   llvm::Timer &getFrontendTimer() const {
     assert(FrontendTimer && "Compiler instance has no frontend timer!");
diff --git a/include/clang/Frontend/FrontendAction.h b/include/clang/Frontend/FrontendAction.h
index c67be92472..fee8d95a05 100644
--- a/include/clang/Frontend/FrontendAction.h
+++ b/include/clang/Frontend/FrontendAction.h
@@ -116,7 +116,7 @@ public:
 
   bool isCurrentFileAST() const {
     assert(!CurrentInput.isEmpty() && "No current file!");
-    return CurrentASTUnit != 0;
+    return CurrentASTUnit.isValid();
   }
 
   const FrontendInputFile &getCurrentInput() const {
diff --git a/include/clang/Lex/HeaderSearch.h b/include/clang/Lex/HeaderSearch.h
index c46c8ce6ef..498de09496 100644
--- a/include/clang/Lex/HeaderSearch.h
+++ b/include/clang/Lex/HeaderSearch.h
@@ -264,7 +264,7 @@ public:
 
   /// \brief Checks whether the map exists or not.
   bool HasIncludeAliasMap() const {
-    return IncludeAliases;
+    return IncludeAliases.isValid();
   }
 
   /// \brief Map the source include name to the dest include name.
diff --git a/include/clang/Lex/MacroInfo.h b/include/clang/Lex/MacroInfo.h
index 64323b7c76..b4ce4db7dd 100644
--- a/include/clang/Lex/MacroInfo.h
+++ b/include/clang/Lex/MacroInfo.h
@@ -421,7 +421,7 @@ public:
     bool isValid() const { return DefDirective != 0; }
     bool isInvalid() const { return !isValid(); }
 
-    operator bool() const { return isValid(); }
+    LLVM_EXPLICIT operator bool() const { return isValid(); }
 
     inline DefInfo getPreviousDefinition(bool AllowHidden = false);
     const DefInfo getPreviousDefinition(bool AllowHidden = false) const {
diff --git a/include/clang/Lex/ModuleMap.h b/include/clang/Lex/ModuleMap.h
index 9fe97d0111..bd57ce4877 100644
--- a/include/clang/Lex/ModuleMap.h
+++ b/include/clang/Lex/ModuleMap.h
@@ -80,7 +80,7 @@ class ModuleMap {
 
     // \brief Whether this known header is valid (i.e., it has an
     // associated module).
-    operator bool() const { return Storage.getPointer() != 0; }
+    LLVM_EXPLICIT operator bool() const { return Storage.getPointer() != 0; }
   };
 
   typedef llvm::DenseMap<const FileEntry *, KnownHeader> HeadersMap;
diff --git a/include/clang/Lex/Preprocessor.h b/include/clang/Lex/Preprocessor.h
index c5981777cd..89cb696f62 100644
--- a/include/clang/Lex/Preprocessor.h
+++ b/include/clang/Lex/Preprocessor.h
@@ -1400,7 +1400,7 @@ private:
   bool InCachingLexMode() const {
     // If the Lexer pointers are 0 and IncludeMacroStack is empty, it means
     // that we are past EOF, not that we are in CachingLex mode.
-    return CurPPLexer == 0 && CurTokenLexer == 0 && CurPTHLexer == 0 &&
+    return !CurPPLexer && !CurTokenLexer && !CurPTHLexer &&
            !IncludeMacroStack.empty();
   }
   void EnterCachingLexMode();
diff --git a/include/clang/Sema/Initialization.h b/include/clang/Sema/Initialization.h
index 58781ac628..3f70672459 100644
--- a/include/clang/Sema/Initialization.h
+++ b/include/clang/Sema/Initialization.h
@@ -841,7 +841,7 @@ public:
   void setSequenceKind(enum SequenceKind SK) { SequenceKind = SK; }
   
   /// \brief Determine whether the initialization sequence is valid.
-  operator bool() const { return !Failed(); }
+  LLVM_EXPLICIT operator bool() const { return !Failed(); }
 
   /// \brief Determine whether the initialization sequence is invalid.
   bool Failed() const { return SequenceKind == FailedSequence; }
diff --git a/include/clang/Sema/Ownership.h b/include/clang/Sema/Ownership.h
index c3d1f4e0b7..92c486db36 100644
--- a/include/clang/Sema/Ownership.h
+++ b/include/clang/Sema/Ownership.h
@@ -65,7 +65,7 @@ namespace clang {
       Ptr = Traits::getAsVoidPointer(P);
     }
 
-    operator bool() const { return Ptr != 0; }
+    LLVM_EXPLICIT operator bool() const { return Ptr != 0; }
 
     void *getAsOpaquePtr() const { return Ptr; }
     static OpaquePtr getFromOpaquePtr(void *P) { return OpaquePtr(P); }
diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index c2300e977e..61b91c5962 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -5994,7 +5994,7 @@ public:
 
     /// \brief Determines whether we have exceeded the maximum
     /// recursive template instantiations.
-    operator bool() const { return Invalid; }
+    LLVM_EXPLICIT operator bool() const { return Invalid; }
 
   private:
     Sema &SemaRef;
diff --git a/include/clang/Sema/TypoCorrection.h b/include/clang/Sema/TypoCorrection.h
index 5fbfba2d5d..59f3417605 100644
--- a/include/clang/Sema/TypoCorrection.h
+++ b/include/clang/Sema/TypoCorrection.h
@@ -140,7 +140,7 @@ public:
   }
 
   /// \brief Returns whether this TypoCorrection has a non-empty DeclarationName
-  operator bool() const { return bool(CorrectionName); }
+  LLVM_EXPLICIT operator bool() const { return bool(CorrectionName); }
 
   /// \brief Mark this TypoCorrection as being a keyword.
   /// Since addCorrectionDeclsand setCorrectionDecl don't allow NULL to be
diff --git a/include/clang/Serialization/ASTReader.h b/include/clang/Serialization/ASTReader.h
index bb59784dff..073baf514c 100644
--- a/include/clang/Serialization/ASTReader.h
+++ b/include/clang/Serialization/ASTReader.h
@@ -1232,7 +1232,7 @@ public:
   void setDeserializationListener(ASTDeserializationListener *Listener);
 
   /// \brief Determine whether this AST reader has a global index.
-  bool hasGlobalIndex() const { return GlobalIndex; }
+  bool hasGlobalIndex() const { return GlobalIndex.isValid(); }
 
   /// \brief Attempts to load the global index.
   ///
diff --git a/include/clang/StaticAnalyzer/Core/BugReporter/PathDiagnostic.h b/include/clang/StaticAnalyzer/Core/BugReporter/PathDiagnostic.h
index a80b5a7a24..09ee005af7 100644
--- a/include/clang/StaticAnalyzer/Core/BugReporter/PathDiagnostic.h
+++ b/include/clang/StaticAnalyzer/Core/BugReporter/PathDiagnostic.h
@@ -504,7 +504,7 @@ public:
   }
   
   bool hasCallStackHint() {
-    return (CallStackHint != 0);
+    return CallStackHint.isValid();
   }
 
   /// Produce the hint for the given node. The node contains 
diff --git a/include/clang/StaticAnalyzer/Core/Checker.h b/include/clang/StaticAnalyzer/Core/Checker.h
index 0dbaab033d..d56f8e9c1d 100644
--- a/include/clang/StaticAnalyzer/Core/Checker.h
+++ b/include/clang/StaticAnalyzer/Core/Checker.h
@@ -505,7 +505,7 @@ struct ImplicitNullDerefEvent {
 struct DefaultBool {
   bool val;
   DefaultBool() : val(false) {}
-  operator bool() const { return val; }
+  LLVM_EXPLICIT operator bool() const { return val; }
   DefaultBool &operator=(bool b) { val = b; return *this; }
 };
 
diff --git a/include/clang/StaticAnalyzer/Core/PathSensitive/Store.h b/include/clang/StaticAnalyzer/Core/PathSensitive/Store.h
index b219495d5f..230ce1ea5c 100644
--- a/include/clang/StaticAnalyzer/Core/PathSensitive/Store.h
+++ b/include/clang/StaticAnalyzer/Core/PathSensitive/Store.h
@@ -231,7 +231,7 @@ public:
 
     bool HandleBinding(StoreManager& SMgr, Store store, const MemRegion* R,
                        SVal val);
-    operator bool() { return First && Binding; }
+    LLVM_EXPLICIT operator bool() { return First && Binding; }
     const MemRegion *getRegion() { return Binding; }
   };
 
diff --git a/lib/AST/ASTDumper.cpp b/lib/AST/ASTDumper.cpp
index 790538fcd0..cd974f0d02 100644
--- a/lib/AST/ASTDumper.cpp
+++ b/lib/AST/ASTDumper.cpp
@@ -1329,7 +1329,7 @@ void ASTDumper::dumpStmt(const Stmt *S) {
     return;
   }
 
-  setMoreChildren(S->children());
+  setMoreChildren(!S->children().empty());
   ConstStmtVisitor<ASTDumper>::Visit(S);
   setMoreChildren(false);
   for (Stmt::const_child_range CI = S->children(); CI; ++CI) {
diff --git a/lib/AST/ASTImporter.cpp b/lib/AST/ASTImporter.cpp
index 740b4ff721..204b9d001c 100644
--- a/lib/AST/ASTImporter.cpp
+++ b/lib/AST/ASTImporter.cpp
@@ -2878,7 +2878,7 @@ Decl *ASTNodeImporter::VisitIndirectFieldDecl(IndirectFieldDecl *D) {
 
       if (Importer.IsStructurallyEquivalent(D->getType(), 
                                             FoundField->getType(),
-                                            Name)) {
+                                            !Name.isEmpty())) {
         Importer.Imported(D, FoundField);
         return FoundField;
       }
diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index 3e4c2cbdb2..b8f478728f 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -2319,7 +2319,7 @@ bool FunctionDecl::doesDeclarationForceExternallyVisibleDefinition() const {
     const FunctionDecl *Prev = this;
     bool FoundBody = false;
     while ((Prev = Prev->getPreviousDecl())) {
-      FoundBody |= Prev->Body;
+      FoundBody |= Prev->Body.isValid();
 
       if (Prev->Body) {
         // If it's not the case that both 'inline' and 'extern' are
@@ -2347,7 +2347,7 @@ bool FunctionDecl::doesDeclarationForceExternallyVisibleDefinition() const {
   const FunctionDecl *Prev = this;
   bool FoundBody = false;
   while ((Prev = Prev->getPreviousDecl())) {
-    FoundBody |= Prev->Body;
+    FoundBody |= Prev->Body.isValid();
     if (RedeclForcesDefC99(Prev))
       return false;
   }
diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index 15cf5ac4ab..f587dfa93e 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -423,7 +423,7 @@ DeclRefExpr *DeclRefExpr::Create(ASTContext &Context,
     FoundD = 0;
 
   std::size_t Size = sizeof(DeclRefExpr);
-  if (QualifierLoc != 0)
+  if (QualifierLoc)
     Size += sizeof(NestedNameSpecifierLoc);
   if (FoundD)
     Size += sizeof(NamedDecl *);
diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index 2a3efb225b..3741bf12d5 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -1809,7 +1809,7 @@ struct CompleteObject {
     assert(Value && "missing value for complete object");
   }
 
-  operator bool() const { return Value; }
+  LLVM_EXPLICIT operator bool() const { return Value; }
 };
 
 /// Find the designated sub-object of an rvalue.
diff --git a/lib/Analysis/CFG.cpp b/lib/Analysis/CFG.cpp
index 096c7a080b..6eb84ce92c 100644
--- a/lib/Analysis/CFG.cpp
+++ b/lib/Analysis/CFG.cpp
@@ -155,7 +155,7 @@ public:
       return !(*this == rhs);
     }
 
-    operator bool() const {
+    LLVM_EXPLICIT operator bool() const {
       return *this != const_iterator();
     }
 
diff --git a/lib/CodeGen/CodeGenFunction.h b/lib/CodeGen/CodeGenFunction.h
index 6caf1689a9..5a7c305c64 100644
--- a/lib/CodeGen/CodeGenFunction.h
+++ b/lib/CodeGen/CodeGenFunction.h
@@ -2422,7 +2422,7 @@ public:
       return ConstantEmission(C, false);
     }
 
-    operator bool() const { return ValueAndIsReference.getOpaqueValue() != 0; }
+    LLVM_EXPLICIT operator bool() const { return ValueAndIsReference.getOpaqueValue() != 0; }
 
     bool isReference() const { return ValueAndIsReference.getInt(); }
     LValue getReferenceLValue(CodeGenFunction &CGF, Expr *refExpr) const {
diff --git a/lib/Lex/HeaderMap.cpp b/lib/Lex/HeaderMap.cpp
index dcf1f0c70c..478462c3c2 100644
--- a/lib/Lex/HeaderMap.cpp
+++ b/lib/Lex/HeaderMap.cpp
@@ -82,7 +82,7 @@ const HeaderMap *HeaderMap::Create(const FileEntry *FE, FileManager &FM) {
   if (FileSize <= sizeof(HMapHeader)) return 0;
 
   OwningPtr<const llvm::MemoryBuffer> FileBuffer(FM.getBufferForFile(FE));
-  if (FileBuffer == 0) return 0;  // Unreadable file?
+  if (!FileBuffer) return 0;  // Unreadable file?
   const char *FileStart = FileBuffer->getBufferStart();
 
   // We know the file is at least as big as the header, check it now.
diff --git a/lib/Lex/PPDirectives.cpp b/lib/Lex/PPDirectives.cpp
index 50a0cb55f7..ba3291aa39 100644
--- a/lib/Lex/PPDirectives.cpp
+++ b/lib/Lex/PPDirectives.cpp
@@ -241,7 +241,7 @@ void Preprocessor::SkipExcludedConditionalBlock(SourceLocation IfTokenLoc,
                                                 bool FoundElse,
                                                 SourceLocation ElseLoc) {
   ++NumSkipped;
-  assert(CurTokenLexer == 0 && CurPPLexer && "Lexing a macro, not a file?");
+  assert(!CurTokenLexer && CurPPLexer && "Lexing a macro, not a file?");
 
   CurPPLexer->pushConditionalLevel(IfTokenLoc, /*isSkipping*/false,
                                  FoundNonSkipPortion, FoundElse);
diff --git a/lib/Lex/PPLexerChange.cpp b/lib/Lex/PPLexerChange.cpp
index be4defe786..a22d67a6ed 100644
--- a/lib/Lex/PPLexerChange.cpp
+++ b/lib/Lex/PPLexerChange.cpp
@@ -70,7 +70,7 @@ PreprocessorLexer *Preprocessor::getCurrentFileLexer() const {
 /// start lexing tokens from it instead of the current buffer.
 void Preprocessor::EnterSourceFile(FileID FID, const DirectoryLookup *CurDir,
                                    SourceLocation Loc) {
-  assert(CurTokenLexer == 0 && "Cannot #include a file inside a macro!");
+  assert(!CurTokenLexer && "Cannot #include a file inside a macro!");
   ++NumEnteredSourceFiles;
 
   if (MaxIncludeStackDepth < IncludeMacroStack.size())
diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
index 6a87b78879..8ad028155a 100644
--- a/lib/Parse/ParseDecl.cpp
+++ b/lib/Parse/ParseDecl.cpp
@@ -2524,7 +2524,7 @@ void Parser::ParseDeclarationSpecifiers(DeclSpec &DS,
       // erroneous: We already checked about that it has no type specifier, and
       // C++ doesn't have implicit int.  Diagnose it as a typo w.r.t. to the
       // typename.
-      if (TypeRep == 0) {
+      if (!TypeRep) {
         ConsumeToken();   // Eat the scope spec so the identifier is current.
         ParsedAttributesWithRange Attrs(AttrFactory);
         if (ParseImplicitInt(DS, &SS, TemplateInfo, AS, DSContext, Attrs)) {
diff --git a/lib/Rewrite/Core/Rewriter.cpp b/lib/Rewrite/Core/Rewriter.cpp
index c1c6595d16..540e8b27fd 100644
--- a/lib/Rewrite/Core/Rewriter.cpp
+++ b/lib/Rewrite/Core/Rewriter.cpp
@@ -463,7 +463,7 @@ public:
     }
   }
 
-  bool ok() { return FileStream; }
+  bool ok() { return FileStream.isValid(); }
   raw_ostream &getStream() { return *FileStream; }
 
 private:
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index e5e43897ee..437a9da422 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -9307,7 +9307,7 @@ void Sema::DefineImplicitMoveAssignment(SourceLocation CurrentLocation,
   ParmVarDecl *Other = MoveAssignOperator->getParamDecl(0);
   QualType OtherRefType = Other->getType()->
       getAs<RValueReferenceType>()->getPointeeType();
-  assert(OtherRefType.getQualifiers() == 0 &&
+  assert(!OtherRefType.getQualifiers() &&
          "Bad argument type of defaulted move assignment");
 
   // Our location for everything implicitly-generated.
diff --git a/lib/Sema/SemaDeclObjC.cpp b/lib/Sema/SemaDeclObjC.cpp
index 07610585c5..3265ab02dc 100644
--- a/lib/Sema/SemaDeclObjC.cpp
+++ b/lib/Sema/SemaDeclObjC.cpp
@@ -2945,7 +2945,7 @@ Decl *Sema::ActOnMethodDeclaration(
     QualType ArgType;
     TypeSourceInfo *DI;
 
-    if (ArgInfo[i].Type == 0) {
+    if (!ArgInfo[i].Type) {
       ArgType = Context.getObjCIdType();
       DI = 0;
     } else {
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 2595f2d099..fa2bfd260b 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -4468,7 +4468,7 @@ Sema::BuildResolvedCallExpr(Expr *Fn, NamedDecl *NDecl,
 ExprResult
 Sema::ActOnCompoundLiteral(SourceLocation LParenLoc, ParsedType Ty,
                            SourceLocation RParenLoc, Expr *InitExpr) {
-  assert((Ty != 0) && "ActOnCompoundLiteral(): missing type");
+  assert(Ty && "ActOnCompoundLiteral(): missing type");
   // FIXME: put back this assert when initializers are worked out.
   //assert((InitExpr != 0) && "ActOnCompoundLiteral(): missing expression");
 
diff --git a/test/SemaCXX/constant-expression-cxx1y.cpp b/test/SemaCXX/constant-expression-cxx1y.cpp
index 59a972a4fd..ea0c9e6526 100644
--- a/test/SemaCXX/constant-expression-cxx1y.cpp
+++ b/test/SemaCXX/constant-expression-cxx1y.cpp
@@ -250,11 +250,12 @@ namespace lifetime {
 }
 
 namespace const_modify {
-  constexpr int modify(int &n) { return n = 1; } // expected-note {{modification of object of const-qualified type 'const int'}}
+  constexpr int modify(int &n) { return n = 1; } // expected-note 2 {{modification of object of const-qualified type 'const int'}}
   constexpr int test1() { int k = 0; return modify(k); }
-  constexpr int test2() { const int k = 0; return modify(const_cast<int&>(k)); } // expected-note {{in call}}
+  constexpr int test2() { const int k = 0; return modify(const_cast<int&>(k)); } // expected-note 2 {{in call}}
   static_assert(test1() == 1, "");
   static_assert(test2() == 1, ""); // expected-error {{constant expression}} expected-note {{in call}}
+  constexpr int i = test2(); // expected-error {{constant expression}} expected-note {{in call}}
 }
 
 namespace null {
diff --git a/unittests/Tooling/CompilationDatabaseTest.cpp b/unittests/Tooling/CompilationDatabaseTest.cpp
index c453b056d2..defde91b26 100644
--- a/unittests/Tooling/CompilationDatabaseTest.cpp
+++ b/unittests/Tooling/CompilationDatabaseTest.cpp
@@ -453,7 +453,7 @@ TEST(ParseFixedCompilationDatabase, ReturnsArgumentsAfterDoubleDash) {
   const char *Argv[] = { "1", "2", "--\0no-constant-folding", "3", "4" };
   OwningPtr<FixedCompilationDatabase> Database(
       FixedCompilationDatabase::loadFromCommandLine(Argc, Argv));
-  ASSERT_TRUE(Database);
+  ASSERT_TRUE(Database.isValid());
   std::vector<CompileCommand> Result =
     Database->getCompileCommands("source");
   ASSERT_EQ(1ul, Result.size());
@@ -472,7 +472,7 @@ TEST(ParseFixedCompilationDatabase, ReturnsEmptyCommandLine) {
   const char *Argv[] = { "1", "2", "--\0no-constant-folding" };
   OwningPtr<FixedCompilationDatabase> Database(
       FixedCompilationDatabase::loadFromCommandLine(Argc, Argv));
-  ASSERT_TRUE(Database);
+  ASSERT_TRUE(Database.isValid());
   std::vector<CompileCommand> Result =
     Database->getCompileCommands("source");
   ASSERT_EQ(1ul, Result.size());