[Demangle] convert microsoftDemangle to take a std::string_view

[nickdesaulniers]

Summary

This should be last of the "bottom-up conversions" of various demanglers
to accept std::string_view. After this, D149104 may be revisited.

[nickdesaulniers]

This patch should have fixed the callsite in llvm::demangle...I will fix that up in D149104 which I am actively rebasing.

lldb/source/Core/Mangled.cpp

if (name) {
     }
   } else {
     m_demangled.Clear();
     m_mangled.Clear();
   }
 }
 
 // Local helpers for different demangling implementations.
-static char *GetMSVCDemangledStr(const char *M) {
+static char *GetMSVCDemangledStr(std::string_view M) {
   char *demangled_cstr = llvm::microsoftDemangle(
       M, nullptr, nullptr,
       llvm::MSDemangleFlags(
           llvm::MSDF_NoAccessSpecifier | llvm::MSDF_NoCallingConvention |
           llvm::MSDF_NoMemberType | llvm::MSDF_NoVariableType));
 
   if (Log *log = GetLog(LLDBLog::Demangle)) {
     if (demangled_cstr && demangled_cstr[0])
-      LLDB_LOGF(log, "demangled msvc: %s -> \"%s\"", M, demangled_cstr);
+      LLDB_LOGF(log, "demangled msvc: %s -> \"%s\"", M.data(), demangled_cstr);
     else
-      LLDB_LOGF(log, "demangled msvc: %s -> error", M);
+      LLDB_LOGF(log, "demangled msvc: %s -> error", M.data());
   }
 
   return demangled_cstr;
 }
 
 static char *GetItaniumDemangledStr(const char *M) {
   char *demangled_cstr = nullptr;
 
case eManglingSchemeItanium:
     // We want the rich mangling info here, so we don't care whether or not
     // there is a demangled string in the pool already.
     return context.FromItaniumName(m_mangled);
 
   case eManglingSchemeMSVC: {
     // We have no rich mangling for MSVC-mangled names yet, so first try to
     // demangle it if necessary.
     if (!m_demangled && !m_mangled.GetMangledCounterpart(m_demangled)) {
-      if (char *d = GetMSVCDemangledStr(m_mangled.GetCString())) {
+      if (char *d = GetMSVCDemangledStr(m_mangled)) {
         // Without the rich mangling info we have to demangle the full name.
         // Copy it to string pool and connect the counterparts to accelerate
         // later access in GetDemangledName().
         m_demangled.SetStringWithMangledCounterpart(llvm::StringRef(d),
                                                     m_mangled);
         ::free(d);
       } else {
         m_demangled.SetCString("");

llvm/include/llvm/Demangle/Demangle.h

 
 /// Demangles the Microsoft symbol pointed at by mangled_name and returns it.
 /// Returns a pointer to the start of a null-terminated demangled string on
 /// success, or nullptr on error.
 /// If n_read is non-null and demangling was successful, it receives how many
 /// bytes of the input string were consumed.
 /// status receives one of the demangle_ enum entries above if it's not nullptr.
 /// Flags controls various details of the demangled representation.
-char *microsoftDemangle(const char *mangled_name, size_t *n_read, int *status,
-                        MSDemangleFlags Flags = MSDF_None);
+char *microsoftDemangle(std::string_view mangled_name, size_t *n_read,
+                        int *status, MSDemangleFlags Flags = MSDF_None);
 
 // Demangles a Rust v0 mangled symbol.
 char *rustDemangle(std::string_view MangledName);
 
 // Demangles a D mangled symbol.
 char *dlangDemangle(std::string_view MangledName);
 
 /// Attempt to demangle a string using different demangling schemes.

llvm/lib/DebugInfo/Symbolize/Symbolize.cpp

LLVMSymbolizer::DemangleName(const std::string &Name,
   std::string Result;
   if (nonMicrosoftDemangle(Name, Result))
     return Result;
 
   if (!Name.empty() && Name.front() == '?') {
     // Only do MSVC C++ demangling on symbols starting with '?'.
     int status = 0;
     char *DemangledName = microsoftDemangle(
-        Name.c_str(), nullptr, &status,
+        Name, nullptr, &status,
         MSDemangleFlags(MSDF_NoAccessSpecifier | MSDF_NoCallingConvention |
                         MSDF_NoMemberType | MSDF_NoReturnType));
     if (status != 0)
       return Name;
     Result = DemangledName;
     free(DemangledName);
     return Result;
   }

llvm/lib/Demangle/MicrosoftDemangle.cpp

void Demangler::dumpBackReferences() {
   for (size_t I = 0; I < Backrefs.NamesCount; ++I) {
     std::printf("  [%d] - %.*s\n", (int)I, (int)Backrefs.Names[I]->Name.size(),
                 &*Backrefs.Names[I]->Name.begin());
   }
   if (Backrefs.NamesCount > 0)
     std::printf("\n");
 }
 
-char *llvm::microsoftDemangle(const char *MangledName, size_t *NMangled,
+char *llvm::microsoftDemangle(std::string_view MangledName, size_t *NMangled,
                               int *Status, MSDemangleFlags Flags) {
   Demangler D;
 
   std::string_view Name{MangledName};
   SymbolNode *AST = D.parse(Name);
   if (!D.Error && NMangled)
-    *NMangled = Name.empty() ? 0 : &*Name.begin() - MangledName;
+    *NMangled = Name.empty() ? 0 : &*Name.begin() - &*MangledName.begin();
 
   if (Flags & MSDF_DumpBackrefs)
     D.dumpBackReferences();
 
   OutputFlags OF = OF_Default;
   if (Flags & MSDF_NoCallingConvention)
     OF = OutputFlags(OF | OF_NoCallingConvention);
   if (Flags & MSDF_NoAccessSpecifier)

llvm/tools/llvm-objdump/COFFDump.cpp

outs() << "[" << format("%2d", SI) << "]"
            << "(ty " << format("%3x", unsigned(Symbol->getType())) << ")"
            << "(scl " << format("%3x", unsigned(Symbol->getStorageClass()))
            << ") "
            << "(nx " << unsigned(Symbol->getNumberOfAuxSymbols()) << ") "
            << "0x" << format("%08x", unsigned(Symbol->getValue())) << " "
            << Name;
     if (Demangle && Name.startswith("?")) {
       int Status = -1;
-      char *DemangledSymbol = microsoftDemangle(Name.data(), nullptr, &Status);
+      char *DemangledSymbol = microsoftDemangle(Name, nullptr, &Status);
 
       if (Status == 0 && DemangledSymbol) {
         outs() << " (" << StringRef(DemangledSymbol) << ")";
         std::free(DemangledSymbol);
       } else {
         outs() << " (invalid mangled name)";
       }
     }

llvm/tools/llvm-undname/llvm-undname.cpp

static bool msDemangle(const std::string &S) {
   if (NoReturnType)
     Flags = MSDemangleFlags(Flags | MSDF_NoReturnType);
   if (NoMemberType)
     Flags = MSDemangleFlags(Flags | MSDF_NoMemberType);
   if (NoVariableType)
     Flags = MSDemangleFlags(Flags | MSDF_NoVariableType);
 
   size_t NRead;
-  char *ResultBuf = microsoftDemangle(S.c_str(), &NRead, &Status, Flags);
+  char *ResultBuf = microsoftDemangle(S, &NRead, &Status, Flags);
   if (Status == llvm::demangle_success) {
     outs() << ResultBuf << "\n";
     outs().flush();
     if (WarnTrailing && NRead < S.size())
       WithColor::warning() << "trailing characters: " << S.c_str() + NRead
                            << "\n";
   } else {
     WithColor::error() << "Invalid mangled name\n";