[ELF] - Do not forget file name when reporting duplicate symbol error for absolute symbols.

[grimar]

Summary

When there is a duplicate absolute symbol, LLD reports <internal>
instead of known object file name currently.
Patch fixes the issue.

[ruiu]

LGTM

ELF/SymbolTable.cpp

else
     error(Msg);
 }
 
 static void reportDuplicate(Symbol *Sym, InputFile *NewFile) {
   warnOrError("duplicate symbol: " + toString(*Sym) + "\n>>> defined in " +
               toString(Sym->File) + "\n>>> defined in " + toString(NewFile));
 }
 
-static void reportDuplicate(Symbol *Sym, InputSectionBase *ErrSec,
-                            uint64_t ErrOffset) {
+static void reportDuplicate(Symbol *Sym, InputFile *NewFile,
+                            InputSectionBase *ErrSec, uint64_t ErrOffset) {
   Defined *D = cast<Defined>(Sym);
   if (!D->Section || !ErrSec) {
-    reportDuplicate(Sym, ErrSec ? ErrSec->File : nullptr);
+    reportDuplicate(Sym, NewFile);
     return;
   }
 
   // Construct and print an error message in the form of:
   //
   //   ld.lld: error: duplicate symbol: foo
   //   >>> defined at bar.c:30
   //   >>>            bar.o (/home/alice/src/bar.o)
Symbol *SymbolTable::addRegular(StringRef Name, uint8_t StOther, uint8_t Type,
   std::tie(S, WasInserted) = insert(Name, Type, getVisibility(StOther),
                                     /*CanOmitFromDynSym*/ false, File);
   int Cmp = compareDefinedNonCommon(S, WasInserted, Binding, Section == nullptr,
                                     Value, Name);
   if (Cmp > 0)
     replaceSymbol<Defined>(S, File, Name, Binding, StOther, Type, Value, Size,
                            Section);
   else if (Cmp == 0)
-    reportDuplicate(S, dyn_cast_or_null<InputSectionBase>(Section), Value);
+    reportDuplicate(S, File, dyn_cast_or_null<InputSectionBase>(Section),
+                    Value);
   return S;
 }
 
 template <typename ELFT>
 void SymbolTable::addShared(StringRef Name, SharedFile<ELFT> &File,
                             const typename ELFT::Sym &Sym, uint32_t Alignment,
                             uint32_t VerdefIndex) {
   // DSO symbols do not affect visibility in the output, so we pass STV_DEFAULT

test/ELF/abs-conflict.s

 foo = 0x123
 
 // RUN: echo ".global foo; foo = 0x124" >  %t2.s
 // RUN: llvm-mc -filetype=obj -triple=x86_64-pc-linux %t2.s -o %t2.o
 // RUN: not ld.lld %t.o %t2.o -o %t.so -shared 2>&1 | FileCheck --check-prefix=DUP %s
 
 // DUP:      duplicate symbol: foo
 // DUP-NEXT: >>> defined in {{.*}}.o
-// DUP-NEXT: >>> defined in <internal>
+// DUP-NEXT: >>> defined in {{.*}}2.o