[MC] Remove SMRange(std::nullopt_t) (llvm#165832)

This patch removes SMRange(std::nullopt_t) to reduce the number of
uses of std::nullopt outside the context of std::optional.  Since
there are only a handful of uses, this patch removes the constructor
without going through deprecation.

The use of std::nullopt here has its root in llvm::None, which was
used as a convenient way to indicate "nothing" before we migrated
llvm::Optional to std::optional.

Author: kazutakahirata

llvm/include/llvm/MC/MCParser/MCAsmParser.h

@@ -209,28 +209,25 @@ class LLVM_ABI MCAsmParser {
       MCInstPrinter *IP, MCAsmParserSemaCallback &SI) = 0;
 
   /// Emit a note at the location \p L, with the message \p Msg.
-  virtual void Note(SMLoc L, const Twine &Msg,
-                    SMRange Range = std::nullopt) = 0;
+  virtual void Note(SMLoc L, const Twine &Msg, SMRange Range = {}) = 0;
 
   /// Emit a warning at the location \p L, with the message \p Msg.
   ///
   /// \return The return value is true, if warnings are fatal.
-  virtual bool Warning(SMLoc L, const Twine &Msg,
-                       SMRange Range = std::nullopt) = 0;
+  virtual bool Warning(SMLoc L, const Twine &Msg, SMRange Range = {}) = 0;
 
   /// Return an error at the location \p L, with the message \p Msg. This
   /// may be modified before being emitted.
   ///
   /// \return The return value is always true, as an idiomatic convenience to
   /// clients.
-  bool Error(SMLoc L, const Twine &Msg, SMRange Range = std::nullopt);
+  bool Error(SMLoc L, const Twine &Msg, SMRange Range = {});
 
   /// Emit an error at the location \p L, with the message \p Msg.
   ///
   /// \return The return value is always true, as an idiomatic convenience to
   /// clients.
-  virtual bool printError(SMLoc L, const Twine &Msg,
-                          SMRange Range = std::nullopt) = 0;
+  virtual bool printError(SMLoc L, const Twine &Msg, SMRange Range = {}) = 0;
 
   bool hasPendingError() { return !PendingErrors.empty(); }
 
@@ -255,7 +252,7 @@ class LLVM_ABI MCAsmParser {
   const AsmToken &getTok() const;
 
   /// Report an error at the current lexer location.
-  bool TokError(const Twine &Msg, SMRange Range = std::nullopt);
+  bool TokError(const Twine &Msg, SMRange Range = {});
 
   bool parseTokenLoc(SMLoc &Loc);
   bool parseToken(AsmToken::TokenKind T, const Twine &Msg = "unexpected token");

llvm/include/llvm/Support/SMLoc.h

@@ -15,7 +15,6 @@
 #define LLVM_SUPPORT_SMLOC_H
 
 #include <cassert>
-#include <optional>
 
 namespace llvm {
 
@@ -50,7 +49,6 @@ class SMRange {
   SMLoc Start, End;
 
   SMRange() = default;
-  SMRange(std::nullopt_t) {}
   SMRange(SMLoc St, SMLoc En) : Start(St), End(En) {
     assert(Start.isValid() == End.isValid() &&
            "Start and End should either both be valid or both be invalid!");

llvm/lib/FileCheck/FileCheckImpl.h

@@ -528,7 +528,7 @@ class ErrorDiagnostic : public ErrorInfo<ErrorDiagnostic> {
   SMRange getRange() const { return Range; }
 
   static Error get(const SourceMgr &SM, SMLoc Loc, const Twine &ErrMsg,
-                   SMRange Range = std::nullopt) {
+                   SMRange Range = {}) {
     return make_error<ErrorDiagnostic>(
         SM.GetMessage(Loc, SourceMgr::DK_Error, ErrMsg), Range);
   }

llvm/lib/MC/MCParser/AsmParser.cpp

@@ -228,11 +228,9 @@ class AsmParser : public MCAsmParser {
     AssemblerDialect = i;
   }
 
-  void Note(SMLoc L, const Twine &Msg, SMRange Range = std::nullopt) override;
-  bool Warning(SMLoc L, const Twine &Msg,
-               SMRange Range = std::nullopt) override;
-  bool printError(SMLoc L, const Twine &Msg,
-                  SMRange Range = std::nullopt) override;
+  void Note(SMLoc L, const Twine &Msg, SMRange Range = {}) override;
+  bool Warning(SMLoc L, const Twine &Msg, SMRange Range = {}) override;
+  bool printError(SMLoc L, const Twine &Msg, SMRange Range = {}) override;
 
   const AsmToken &Lex() override;
 
@@ -312,7 +310,7 @@ class AsmParser : public MCAsmParser {
 
   void printMacroInstantiations();
   void printMessage(SMLoc Loc, SourceMgr::DiagKind Kind, const Twine &Msg,
-                    SMRange Range = std::nullopt) const {
+                    SMRange Range = {}) const {
     ArrayRef<SMRange> Ranges(Range);
     SrcMgr.PrintMessage(Loc, Kind, Msg, Ranges);
   }

llvm/lib/MC/MCParser/MasmParser.cpp

@@ -483,11 +483,9 @@ class MasmParser : public MCAsmParser {
     AssemblerDialect = i;
   }
 
-  void Note(SMLoc L, const Twine &Msg, SMRange Range = std::nullopt) override;
-  bool Warning(SMLoc L, const Twine &Msg,
-               SMRange Range = std::nullopt) override;
-  bool printError(SMLoc L, const Twine &Msg,
-                  SMRange Range = std::nullopt) override;
+  void Note(SMLoc L, const Twine &Msg, SMRange Range = {}) override;
+  bool Warning(SMLoc L, const Twine &Msg, SMRange Range = {}) override;
+  bool printError(SMLoc L, const Twine &Msg, SMRange Range = {}) override;
 
   enum ExpandKind { ExpandMacros, DoNotExpandMacros };
   const AsmToken &Lex(ExpandKind ExpandNextToken);
@@ -592,7 +590,7 @@ class MasmParser : public MCAsmParser {
   bool expandStatement(SMLoc Loc);
 
   void printMessage(SMLoc Loc, SourceMgr::DiagKind Kind, const Twine &Msg,
-                    SMRange Range = std::nullopt) const {
+                    SMRange Range = {}) const {
     ArrayRef<SMRange> Ranges(Range);
     SrcMgr.PrintMessage(Loc, Kind, Msg, Ranges);
   }

llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp

@@ -426,15 +426,15 @@ class ARMAsmParser : public MCTargetAsmParser {
       VPTState.CurPosition = ~0U;
   }
 
-  void Note(SMLoc L, const Twine &Msg, SMRange Range = std::nullopt) {
+  void Note(SMLoc L, const Twine &Msg, SMRange Range = {}) {
     return getParser().Note(L, Msg, Range);
   }
 
-  bool Warning(SMLoc L, const Twine &Msg, SMRange Range = std::nullopt) {
+  bool Warning(SMLoc L, const Twine &Msg, SMRange Range = {}) {
     return getParser().Warning(L, Msg, Range);
   }
 
-  bool Error(SMLoc L, const Twine &Msg, SMRange Range = std::nullopt) {
+  bool Error(SMLoc L, const Twine &Msg, SMRange Range = {}) {
     return getParser().Error(L, Msg, Range);
   }
 

llvm/lib/Target/X86/AsmParser/X86AsmParser.cpp

@@ -1121,7 +1121,7 @@ class X86AsmParser : public MCTargetAsmParser {
     void setTypeInfo(AsmTypeInfo Type) { CurType = Type; }
   };
 
-  bool Error(SMLoc L, const Twine &Msg, SMRange Range = std::nullopt,
+  bool Error(SMLoc L, const Twine &Msg, SMRange Range = {},
              bool MatchingInlineAsm = false) {
     MCAsmParser &Parser = getParser();
     if (MatchingInlineAsm) {
@@ -4322,7 +4322,7 @@ bool X86AsmParser::matchAndEmitATTInstruction(
     SMLoc IDLoc, unsigned &Opcode, MCInst &Inst, OperandVector &Operands,
     MCStreamer &Out, uint64_t &ErrorInfo, bool MatchingInlineAsm) {
   X86Operand &Op = static_cast<X86Operand &>(*Operands[0]);
-  SMRange EmptyRange = std::nullopt;
+  SMRange EmptyRange;
   // In 16-bit mode, if data32 is specified, temporarily switch to 32-bit mode
   // when matching the instruction.
   if (ForcedDataPrefix == X86::Is32Bit)
@@ -4548,7 +4548,7 @@ bool X86AsmParser::matchAndEmitIntelInstruction(
     SMLoc IDLoc, unsigned &Opcode, MCInst &Inst, OperandVector &Operands,
     MCStreamer &Out, uint64_t &ErrorInfo, bool MatchingInlineAsm) {
   X86Operand &Op = static_cast<X86Operand &>(*Operands[0]);
-  SMRange EmptyRange = std::nullopt;
+  SMRange EmptyRange;
   // Find one unsized memory operand, if present.
   X86Operand *UnsizedMemOp = nullptr;
   for (const auto &Op : Operands) {

llvm/utils/TableGen/AsmMatcherEmitter.cpp

@@ -4164,7 +4164,7 @@ void AsmMatcherEmitter::run(raw_ostream &OS) {
     OS << "        MII.getDeprecatedInfo(Inst, getSTI(), Info)) {\n";
     OS << "      SMLoc Loc = ((" << Target.getName()
        << "Operand &)*Operands[0]).getStartLoc();\n";
-    OS << "      getParser().Warning(Loc, Info, std::nullopt);\n";
+    OS << "      getParser().Warning(Loc, Info, {});\n";
     OS << "    }\n";
   }