[clang][NFC] Refactor StringLiteral::StringKind

This patch converts `StringLiteral::StringKind` to a scoped enum in namespace scope. This enabled forward-declarations of this enum where necessary, e.g. for `preferred_type` annotation for bit-fields.

clang/include/clang/AST/Expr.h

@@ -1786,6 +1786,15 @@ class ImaginaryLiteral : public Expr {
   }
 };
 
+enum class StringLiteralKind {
+  Ordinary,
+  Wide,
+  UTF8,
+  UTF16,
+  UTF32,
+  Unevaluated
+};
+
 /// StringLiteral - This represents a string literal expression, e.g. "foo"
 /// or L"bar" (wide strings). The actual string data can be obtained with
 /// getBytes() and is NOT null-terminated. The length of the string data is
@@ -1825,7 +1834,7 @@ class StringLiteral final
   /// * An array of getByteLength() char used to store the string data.
 
 public:
-  enum StringKind { Ordinary, Wide, UTF8, UTF16, UTF32, Unevaluated };
+  // enum StringKind { Ordinary, Wide, UTF8, UTF16, UTF32, Unevaluated };
 
 private:
   unsigned numTrailingObjects(OverloadToken<unsigned>) const { return 1; }
@@ -1849,7 +1858,7 @@ class StringLiteral final
   }
 
   /// Build a string literal.
-  StringLiteral(const ASTContext &Ctx, StringRef Str, StringKind Kind,
+  StringLiteral(const ASTContext &Ctx, StringRef Str, StringLiteralKind Kind,
                 bool Pascal, QualType Ty, const SourceLocation *Loc,
                 unsigned NumConcatenated);
 
@@ -1858,7 +1867,8 @@ class StringLiteral final
                 unsigned CharByteWidth);
 
   /// Map a target and string kind to the appropriate character width.
-  static unsigned mapCharByteWidth(TargetInfo const &Target, StringKind SK);
+  static unsigned mapCharByteWidth(TargetInfo const &Target,
+                                   StringLiteralKind SK);
 
   /// Set one of the string literal token.
   void setStrTokenLoc(unsigned TokNum, SourceLocation L) {
@@ -1870,13 +1880,13 @@ class StringLiteral final
   /// This is the "fully general" constructor that allows representation of
   /// strings formed from multiple concatenated tokens.
   static StringLiteral *Create(const ASTContext &Ctx, StringRef Str,
-                               StringKind Kind, bool Pascal, QualType Ty,
+                               StringLiteralKind Kind, bool Pascal, QualType Ty,
                                const SourceLocation *Loc,
                                unsigned NumConcatenated);
 
   /// Simple constructor for string literals made from one token.
   static StringLiteral *Create(const ASTContext &Ctx, StringRef Str,
-                               StringKind Kind, bool Pascal, QualType Ty,
+                               StringLiteralKind Kind, bool Pascal, QualType Ty,
                                SourceLocation Loc) {
     return Create(Ctx, Str, Kind, Pascal, Ty, &Loc, 1);
   }
@@ -1918,16 +1928,16 @@ class StringLiteral final
   unsigned getLength() const { return *getTrailingObjects<unsigned>(); }
   unsigned getCharByteWidth() const { return StringLiteralBits.CharByteWidth; }
 
-  StringKind getKind() const {
-    return static_cast<StringKind>(StringLiteralBits.Kind);
+  StringLiteralKind getKind() const {
+    return static_cast<StringLiteralKind>(StringLiteralBits.Kind);
   }
 
-  bool isOrdinary() const { return getKind() == Ordinary; }
-  bool isWide() const { return getKind() == Wide; }
-  bool isUTF8() const { return getKind() == UTF8; }
-  bool isUTF16() const { return getKind() == UTF16; }
-  bool isUTF32() const { return getKind() == UTF32; }
-  bool isUnevaluated() const { return getKind() == Unevaluated; }
+  bool isOrdinary() const { return getKind() == StringLiteralKind::Ordinary; }
+  bool isWide() const { return getKind() == StringLiteralKind::Wide; }
+  bool isUTF8() const { return getKind() == StringLiteralKind::UTF8; }
+  bool isUTF16() const { return getKind() == StringLiteralKind::UTF16; }
+  bool isUTF32() const { return getKind() == StringLiteralKind::UTF32; }
+  bool isUnevaluated() const { return getKind() == StringLiteralKind::Unevaluated; }
   bool isPascal() const { return StringLiteralBits.IsPascal; }
 
   bool containsNonAscii() const {

clang/lib/AST/ASTContext.cpp

@@ -12221,7 +12221,7 @@ ASTContext::getPredefinedStringLiteralFromCache(StringRef Key) const {
   StringLiteral *&Result = StringLiteralCache[Key];
   if (!Result)
     Result = StringLiteral::Create(
-        *this, Key, StringLiteral::Ordinary,
+        *this, Key, StringLiteralKind::Ordinary,
         /*Pascal*/ false, getStringLiteralArrayType(CharTy, Key.size()),
         SourceLocation());
   return Result;

clang/lib/AST/Expr.cpp

@@ -1060,23 +1060,23 @@ double FloatingLiteral::getValueAsApproximateDouble() const {
 }
 
 unsigned StringLiteral::mapCharByteWidth(TargetInfo const &Target,
-                                         StringKind SK) {
+                                         StringLiteralKind SK) {
   unsigned CharByteWidth = 0;
   switch (SK) {
-  case Ordinary:
-  case UTF8:
+  case StringLiteralKind::Ordinary:
+  case StringLiteralKind::UTF8:
     CharByteWidth = Target.getCharWidth();
     break;
-  case Wide:
+  case StringLiteralKind::Wide:
     CharByteWidth = Target.getWCharWidth();
     break;
-  case UTF16:
+  case StringLiteralKind::UTF16:
     CharByteWidth = Target.getChar16Width();
     break;
-  case UTF32:
+  case StringLiteralKind::UTF32:
     CharByteWidth = Target.getChar32Width();
     break;
-  case Unevaluated:
+  case StringLiteralKind::Unevaluated:
     return sizeof(char); // Host;
   }
   assert((CharByteWidth & 7) == 0 && "Assumes character size is byte multiple");
@@ -1087,17 +1087,17 @@ unsigned StringLiteral::mapCharByteWidth(TargetInfo const &Target,
 }
 
 StringLiteral::StringLiteral(const ASTContext &Ctx, StringRef Str,
-                             StringKind Kind, bool Pascal, QualType Ty,
+                             StringLiteralKind Kind, bool Pascal, QualType Ty,
                              const SourceLocation *Loc,
                              unsigned NumConcatenated)
     : Expr(StringLiteralClass, Ty, VK_LValue, OK_Ordinary) {
 
   unsigned Length = Str.size();
 
-  StringLiteralBits.Kind = Kind;
+  StringLiteralBits.Kind = llvm::to_underlying(Kind);
   StringLiteralBits.NumConcatenated = NumConcatenated;
 
-  if (Kind != StringKind::Unevaluated) {
+  if (Kind != StringLiteralKind::Unevaluated) {
     assert(Ctx.getAsConstantArrayType(Ty) &&
            "StringLiteral must be of constant array type!");
     unsigned CharByteWidth = mapCharByteWidth(Ctx.getTargetInfo(), Kind);
@@ -1152,8 +1152,8 @@ StringLiteral::StringLiteral(EmptyShell Empty, unsigned NumConcatenated,
 }
 
 StringLiteral *StringLiteral::Create(const ASTContext &Ctx, StringRef Str,
-                                     StringKind Kind, bool Pascal, QualType Ty,
-                                     const SourceLocation *Loc,
+                                     StringLiteralKind Kind, bool Pascal,
+                                     QualType Ty, const SourceLocation *Loc,
                                      unsigned NumConcatenated) {
   void *Mem = Ctx.Allocate(totalSizeToAlloc<unsigned, SourceLocation, char>(
                                1, NumConcatenated, Str.size()),
@@ -1175,13 +1175,21 @@ StringLiteral *StringLiteral::CreateEmpty(const ASTContext &Ctx,
 
 void StringLiteral::outputString(raw_ostream &OS) const {
   switch (getKind()) {
-  case Unevaluated:
-  case Ordinary:
+  case StringLiteralKind::Unevaluated:
+  case StringLiteralKind::Ordinary:
     break; // no prefix.
-  case Wide:  OS << 'L'; break;
-  case UTF8:  OS << "u8"; break;
-  case UTF16: OS << 'u'; break;
-  case UTF32: OS << 'U'; break;
+  case StringLiteralKind::Wide:
+    OS << 'L';
+    break;
+  case StringLiteralKind::UTF8:
+    OS << "u8";
+    break;
+  case StringLiteralKind::UTF16:
+    OS << 'u';
+    break;
+  case StringLiteralKind::UTF32:
+    OS << 'U';
+    break;
   }
   OS << '"';
   static const char Hex[] = "0123456789ABCDEF";
@@ -1195,8 +1203,8 @@ void StringLiteral::outputString(raw_ostream &OS) const {
 
       // Convert UTF-16 surrogate pairs back to codepoints before rendering.
       // Leave invalid surrogates alone; we'll use \x for those.
-      if (getKind() == UTF16 && I != N - 1 && Char >= 0xd800 &&
-          Char <= 0xdbff) {
+      if (getKind() == StringLiteralKind::UTF16 && I != N - 1 &&
+          Char >= 0xd800 && Char <= 0xdbff) {
         uint32_t Trail = getCodeUnit(I + 1);
         if (Trail >= 0xdc00 && Trail <= 0xdfff) {
           Char = 0x10000 + ((Char - 0xd800) << 10) + (Trail - 0xdc00);
@@ -1208,7 +1216,7 @@ void StringLiteral::outputString(raw_ostream &OS) const {
         // If this is a wide string, output characters over 0xff using \x
         // escapes. Otherwise, this is a UTF-16 or UTF-32 string, and Char is a
         // codepoint: use \x escapes for invalid codepoints.
-        if (getKind() == Wide ||
+        if (getKind() == StringLiteralKind::Wide ||
             (Char >= 0xd800 && Char <= 0xdfff) || Char >= 0x110000) {
           // FIXME: Is this the best way to print wchar_t?
           OS << "\\x";
@@ -1285,9 +1293,9 @@ StringLiteral::getLocationOfByte(unsigned ByteNo, const SourceManager &SM,
                                  const LangOptions &Features,
                                  const TargetInfo &Target, unsigned *StartToken,
                                  unsigned *StartTokenByteOffset) const {
-  assert((getKind() == StringLiteral::Ordinary ||
-          getKind() == StringLiteral::UTF8 ||
-          getKind() == StringLiteral::Unevaluated) &&
+  assert((getKind() == StringLiteralKind::Ordinary ||
+          getKind() == StringLiteralKind::UTF8 ||
+          getKind() == StringLiteralKind::Unevaluated) &&
          "Only narrow string literals are currently supported");
 
   // Loop over all of the tokens in this string until we find the one that

clang/lib/AST/ExprConstant.cpp

@@ -9043,7 +9043,7 @@ class PointerExprEvaluator
         CharTy, Size, nullptr, ArraySizeModifier::Normal, 0);
 
     StringLiteral *SL =
-        StringLiteral::Create(Info.Ctx, ResultStr, StringLiteral::Ordinary,
+        StringLiteral::Create(Info.Ctx, ResultStr, StringLiteralKind::Ordinary,
                               /*Pascal*/ false, ArrayTy, E->getLocation());
 
     evaluateLValue(SL, Result);

clang/lib/AST/StmtProfile.cpp

@@ -1371,7 +1371,7 @@ void StmtProfiler::VisitImaginaryLiteral(const ImaginaryLiteral *S) {
 void StmtProfiler::VisitStringLiteral(const StringLiteral *S) {
   VisitExpr(S);
   ID.AddString(S->getBytes());
-  ID.AddInteger(S->getKind());
+  ID.AddInteger(llvm::to_underlying(S->getKind()));
 }
 
 void StmtProfiler::VisitParenExpr(const ParenExpr *S) {

clang/lib/Frontend/Rewrite/RewriteModernObjC.cpp

@@ -601,7 +601,7 @@ namespace {
       QualType StrType = Context->getConstantArrayType(
           Context->CharTy, llvm::APInt(32, Str.size() + 1), nullptr,
           ArraySizeModifier::Normal, 0);
-      return StringLiteral::Create(*Context, Str, StringLiteral::Ordinary,
+      return StringLiteral::Create(*Context, Str, StringLiteralKind::Ordinary,
                                    /*Pascal=*/false, StrType, SourceLocation());
     }
   };

clang/lib/Frontend/Rewrite/RewriteObjC.cpp

@@ -500,7 +500,7 @@ namespace {
       QualType StrType = Context->getConstantArrayType(
           Context->CharTy, llvm::APInt(32, Str.size() + 1), nullptr,
           ArraySizeModifier::Normal, 0);
-      return StringLiteral::Create(*Context, Str, StringLiteral::Ordinary,
+      return StringLiteral::Create(*Context, Str, StringLiteralKind::Ordinary,
                                    /*Pascal=*/false, StrType, SourceLocation());
     }
   };

clang/lib/Sema/SemaChecking.cpp

@@ -10130,7 +10130,7 @@ class FormatStringLiteral {
   unsigned getLength() const { return FExpr->getLength() - Offset; }
   unsigned getCharByteWidth() const { return FExpr->getCharByteWidth(); }
 
-  StringLiteral::StringKind getKind() const { return FExpr->getKind(); }
+  StringLiteralKind getKind() const { return FExpr->getKind(); }
 
   QualType getType() const { return FExpr->getType(); }
 

clang/lib/Sema/SemaExpr.cpp

@@ -1969,7 +1969,7 @@ ExprResult Sema::ActOnUnevaluatedStringLiteral(ArrayRef<Token> StringToks) {
     StringTokLocs.push_back(Tok.getLocation());
 
   StringLiteral *Lit = StringLiteral::Create(
-      Context, Literal.GetString(), StringLiteral::Unevaluated, false, {},
+      Context, Literal.GetString(), StringLiteralKind::Unevaluated, false, {},
       &StringTokLocs[0], StringTokLocs.size());
 
   if (!Literal.getUDSuffix().empty()) {
@@ -2055,28 +2055,28 @@ Sema::ActOnStringLiteral(ArrayRef<Token> StringToks, Scope *UDLScope) {
     StringTokLocs.push_back(Tok.getLocation());
 
   QualType CharTy = Context.CharTy;
-  StringLiteral::StringKind Kind = StringLiteral::Ordinary;
+  StringLiteralKind Kind = StringLiteralKind::Ordinary;
   if (Literal.isWide()) {
     CharTy = Context.getWideCharType();
-    Kind = StringLiteral::Wide;
+    Kind = StringLiteralKind::Wide;
   } else if (Literal.isUTF8()) {
     if (getLangOpts().Char8)
       CharTy = Context.Char8Ty;
-    Kind = StringLiteral::UTF8;
+    Kind = StringLiteralKind::UTF8;
   } else if (Literal.isUTF16()) {
     CharTy = Context.Char16Ty;
-    Kind = StringLiteral::UTF16;
+    Kind = StringLiteralKind::UTF16;
   } else if (Literal.isUTF32()) {
     CharTy = Context.Char32Ty;
-    Kind = StringLiteral::UTF32;
+    Kind = StringLiteralKind::UTF32;
   } else if (Literal.isPascal()) {
     CharTy = Context.UnsignedCharTy;
   }
 
   // Warn on initializing an array of char from a u8 string literal; this
   // becomes ill-formed in C++2a.
   if (getLangOpts().CPlusPlus && !getLangOpts().CPlusPlus20 &&
-      !getLangOpts().Char8 && Kind == StringLiteral::UTF8) {
+      !getLangOpts().Char8 && Kind == StringLiteralKind::UTF8) {
     Diag(StringTokLocs.front(), diag::warn_cxx20_compat_utf8_string);
 
     // Create removals for all 'u8' prefixes in the string literal(s). This
@@ -3743,14 +3743,14 @@ ExprResult Sema::BuildPredefinedExpr(SourceLocation Loc,
       ResTy = Context.getConstantArrayType(ResTy, LengthI, nullptr,
                                            ArraySizeModifier::Normal,
                                            /*IndexTypeQuals*/ 0);
-      SL = StringLiteral::Create(Context, RawChars, StringLiteral::Wide,
+      SL = StringLiteral::Create(Context, RawChars, StringLiteralKind::Wide,
                                  /*Pascal*/ false, ResTy, Loc);
     } else {
       ResTy = Context.adjustStringLiteralBaseType(Context.CharTy.withConst());
       ResTy = Context.getConstantArrayType(ResTy, LengthI, nullptr,
                                            ArraySizeModifier::Normal,
                                            /*IndexTypeQuals*/ 0);
-      SL = StringLiteral::Create(Context, Str, StringLiteral::Ordinary,
+      SL = StringLiteral::Create(Context, Str, StringLiteralKind::Ordinary,
                                  /*Pascal*/ false, ResTy, Loc);
     }
   }
@@ -4006,7 +4006,7 @@ ExprResult Sema::ActOnNumericConstant(const Token &Tok, Scope *UDLScope) {
           llvm::APInt(32, Length + 1), nullptr, ArraySizeModifier::Normal, 0);
       Expr *Lit =
           StringLiteral::Create(Context, StringRef(TokSpelling.data(), Length),
-                                StringLiteral::Ordinary,
+                                StringLiteralKind::Ordinary,
                                 /*Pascal*/ false, StrTy, &TokLoc, 1);
       return BuildLiteralOperatorCall(R, OpNameInfo, Lit, TokLoc);
     }

clang/lib/Sema/SemaExprCXX.cpp

@@ -4105,20 +4105,20 @@ Sema::IsStringLiteralToNonConstPointerConversion(Expr *From, QualType ToType) {
         // explicit appropriate pointer target type (C++ 4.2p2).
         if (!ToPtrType->getPointeeType().hasQualifiers()) {
           switch (StrLit->getKind()) {
-            case StringLiteral::UTF8:
-            case StringLiteral::UTF16:
-            case StringLiteral::UTF32:
-              // We don't allow UTF literals to be implicitly converted
-              break;
-            case StringLiteral::Ordinary:
-              return (ToPointeeType->getKind() == BuiltinType::Char_U ||
-                      ToPointeeType->getKind() == BuiltinType::Char_S);
-            case StringLiteral::Wide:
-              return Context.typesAreCompatible(Context.getWideCharType(),
-                                                QualType(ToPointeeType, 0));
-            case StringLiteral::Unevaluated:
-              assert(false && "Unevaluated string literal in expression");
-              break;
+          case StringLiteralKind::UTF8:
+          case StringLiteralKind::UTF16:
+          case StringLiteralKind::UTF32:
+            // We don't allow UTF literals to be implicitly converted
+            break;
+          case StringLiteralKind::Ordinary:
+            return (ToPointeeType->getKind() == BuiltinType::Char_U ||
+                    ToPointeeType->getKind() == BuiltinType::Char_S);
+          case StringLiteralKind::Wide:
+            return Context.typesAreCompatible(Context.getWideCharType(),
+                                              QualType(ToPointeeType, 0));
+          case StringLiteralKind::Unevaluated:
+            assert(false && "Unevaluated string literal in expression");
+            break;
           }
         }
       }

clang/lib/Sema/SemaExprObjC.cpp

@@ -71,7 +71,7 @@ ExprResult Sema::ParseObjCStringLiteral(SourceLocation *AtLocs,
     QualType StrTy = Context.getConstantArrayType(
         CAT->getElementType(), llvm::APInt(32, StrBuf.size() + 1), nullptr,
         CAT->getSizeModifier(), CAT->getIndexTypeCVRQualifiers());
-    S = StringLiteral::Create(Context, StrBuf, StringLiteral::Ordinary,
+    S = StringLiteral::Create(Context, StrBuf, StringLiteralKind::Ordinary,
                               /*Pascal=*/false, StrTy, &StrLocs[0],
                               StrLocs.size());
   }