Simplify Symbol::copyFrom

[• rafael]

Summary

This is only used for --wrap and I don't think these fields have a meaningful impact on that feature.

[ruiu]

Then maybe we should just use memcpy?

[• rafael]

Just use memcpy.

[ruiu]

LGTM

[• espindola]

r319265

ELF/SymbolTable.cpp

for (WrappedSymbol &W : WrappedSymbols) {
     // First, make a copy of __real_sym.
     Symbol *Real = nullptr;
     if (W.Real->isDefined()) {
       Real = (Symbol *)make<SymbolUnion>();
       memcpy(Real, W.Real, sizeof(SymbolUnion));
     }
 
     // Replace __real_sym with sym and sym with __wrap_sym.
-    W.Real->copyFrom(W.Sym);
-    W.Sym->copyFrom(W.Wrap);
+    memcpy(W.Real, W.Sym, sizeof(SymbolUnion));
+    memcpy(W.Sym, W.Wrap, sizeof(SymbolUnion));
 
     // We now have two copies of __wrap_sym. Drop one.
     W.Wrap->IsUsedInRegularObj = false;
 
     if (Real)
       SymVector.push_back(Real);
   }
 }

ELF/Symbols.h

public:
   // True is this is an undefined weak symbol. This only works once
   // all input files have been added.
   bool isUndefWeak() const;
 
   InputFile *getFile() const;
   StringRef getName() const { return Name; }
   uint8_t getVisibility() const { return StOther & 0x3; }
   void parseSymbolVersion();
-  void copyFrom(Symbol *Other);
 
   bool isInGot() const { return GotIndex != -1U; }
   bool isInPlt() const { return PltIndex != -1U; }
 
   uint64_t getVA(int64_t Addend = 0) const;
 
   uint64_t getGotOffset() const;
   uint64_t getGotVA() const;

ELF/Symbols.cpp

if (isLocal()) {
     // Local absolute symbols actually have a file, but that is not currently
     // used. We could support that by having a mostly redundant InputFile in
     // Symbol, or having a special absolute section if needed.
     return Sec ? cast<InputSectionBase>(Sec)->File : nullptr;
   }
   return File;
 }
 
-// Overwrites all attributes with Other's so that this symbol becomes
-// an alias to Other. This is useful for handling some options such as
-// --wrap.
-void Symbol::copyFrom(Symbol *Other) {
-  Symbol Sym = *this;
-  memcpy(this, Other, sizeof(SymbolUnion));
-
-  VersionId = Sym.VersionId;
-  IsUsedInRegularObj = Sym.IsUsedInRegularObj;
-  ExportDynamic = Sym.ExportDynamic;
-  CanInline = Sym.CanInline;
-  Traced = Sym.Traced;
-  InVersionScript = Sym.InVersionScript;
-}
-
 uint64_t Symbol::getVA(int64_t Addend) const {
   uint64_t OutVA = getSymVA(*this, Addend);
   return OutVA + Addend;
 }
 
 uint64_t Symbol::getGotVA() const { return InX::Got->getVA() + getGotOffset(); }
 
 uint64_t Symbol::getGotOffset() const {