[ELF] Swap argument names: use Old to refer to original symbol and New for incoming one

[ruiu]

Don't you have to change the test?

[MaskRay]

The test does not change.

The original code uses Old to refer to the incoming symbol while New is for the old symbol. I think it is a bit weird so I swap the names in this revision. Tests are unaffected.

[ruiu]

LGTM

ELF/SymbolTable.cpp

 // files within the same --{start,end}-group get the same group ID. E.g.
 //
 //   ld.lld A B --start-group C D --end-group E
 //
 // A forms group 0. B form group 1. C and D (including their member object
 // files) form group 2. E forms group 3. I think that you can see how this
 // group assignment rule simulates the traditional linker's semantics.
 static void checkBackrefs(StringRef Name, InputFile *Old, InputFile *New) {
-  if (Config->WarnBackrefs && Old && New->GroupId < Old->GroupId)
-    warn("backward reference detected: " + Name + " in " + toString(Old) +
-         " refers to " + toString(New));
+  if (Config->WarnBackrefs && New && Old->GroupId < New->GroupId)
+    warn("backward reference detected: " + Name + " in " + toString(New) +
+         " refers to " + toString(Old));
 }
 
 template <class ELFT>
 Symbol *SymbolTable::addUndefined(StringRef Name, uint8_t Binding,
                                   uint8_t StOther, uint8_t Type,
                                   bool CanOmitFromDynSym, InputFile *File) {
   Symbol *S;
   bool WasInserted;
Symbol *SymbolTable::addUndefined(StringRef Name, uint8_t Binding,
   if (S->isLazy()) {
     // An undefined weak will not fetch archive members. See comment on Lazy in
     // Symbols.h for the details.
     if (Binding == STB_WEAK) {
       S->Type = Type;
       return S;
     }
 
-    checkBackrefs(Name, File, S->File);
+    checkBackrefs(Name, S->File, File);
     fetchLazy<ELFT>(S);
   }
   return S;
 }
 
 // Using .symver foo,foo@@VER unfortunately creates two symbols: foo and
 // foo@@VER. We want to effectively ignore foo, so give precedence to
 // foo@@VER.