[llvm-nm] - Simplify the code in dumpSymbolNamesFromObject. NFC.

[grimar]

Summary

It is possible to simplify the logic that extracts symbol names.

Depends on D94667.
It made the NMSymbol::Name to be std::string, what allowed this simplification.

[jhenderson]

LGTM.

llvm/tools/llvm-nm/llvm-nm.cpp

static void dumpSymbolNamesFromObject(SymbolicFile &Obj, bool printName,
   if (DynamicSyms) {
     const auto *E = dyn_cast<ELFObjectFileBase>(&Obj);
     if (!E) {
       error("File format has no dynamic symbol table", Obj.getFileName());
       return;
     }
     Symbols = E->getDynamicSymbolIterators();
   }
-  std::string NameBuffer;
-  raw_string_ostream OS(NameBuffer);
+
   // If a "-s segname sectname" option was specified and this is a Mach-O
   // file get the section number for that section in this object file.
   unsigned int Nsect = 0;
   MachOObjectFile *MachO = dyn_cast<MachOObjectFile>(&Obj);
   if (!SegSect.empty() && MachO) {
     Nsect = getNsectForSegSect(MachO);
     // If this section is not in the object file no symbols are printed.
     if (Nsect == 0)
for (BasicSymbolRef Sym : Symbols) {
         if (!AddressOrErr) {
           consumeError(AddressOrErr.takeError());
           break;
         }
         S.Address = *AddressOrErr;
       }
       S.TypeName = getNMTypeName(Obj, Sym);
       S.TypeChar = getNMSectionTagAndName(Obj, Sym, S.SectionName);
+
+      raw_string_ostream OS(S.Name);
       if (Error E = Sym.printName(OS)) {
         if (MachO) {
           OS << "bad string index";
           consumeError(std::move(E));
         } else
           error(std::move(E), Obj.getFileName());
       }
-      OS << '\0';
       S.Sym = Sym;
       SymbolList.push_back(S);
     }
   }
 
-  OS.flush();
-  const char *P = NameBuffer.c_str();
-  unsigned I;
-  for (I = 0; I < SymbolList.size(); ++I) {
-    SymbolList[I].Name = P;
-    P += strlen(P) + 1;
-  }
-
   // If this is a Mach-O file where the nlist symbol table is out of sync
   // with the dyld export trie then look through exports and fake up symbols
   // for the ones that are missing (also done with the -add-dyldinfo flag).
   // This is needed if strip(1) -T is run on a binary containing swift
   // language symbols for example.  The option -only-dyldinfo will fake up
   // all symbols from the dyld export trie as well as the bind info.
   if (MachO && !NoDyldInfo)
     dumpSymbolsFromDLInfoMachO(*MachO);