LLD: Inherit constructors. No functionality change.

[ruiu]

Summary

We cannot use "using" to inherit constructors because the feature
is not supported by MSVC 2013.

[atanasyan]

As to me the patch looks good. The code becomes much shorter. But I do not think that std::forward is a common idiom for constructor inheritance. Might it confuse somebody?

[ruiu]

Yup, I'd like to hear from more audiences about their opinions.

lib/ReaderWriter/ELF/ARM/ARMELFFile.h

 
 class ARMLinkingContext;
 
 template <class ELFT> class ARMELFDefinedAtom : public ELFDefinedAtom<ELFT> {
   typedef llvm::object::Elf_Sym_Impl<ELFT> Elf_Sym;
   typedef llvm::object::Elf_Shdr_Impl<ELFT> Elf_Shdr;
 
 public:
-  ARMELFDefinedAtom(const ELFFile<ELFT> &file, StringRef symbolName,
-                 StringRef sectionName, const Elf_Sym *symbol,
-                 const Elf_Shdr *section, ArrayRef<uint8_t> contentData,
-                 unsigned int referenceStart, unsigned int referenceEnd,
-                 std::vector<ELFReference<ELFT> *> &referenceList)
-      : ELFDefinedAtom<ELFT>(file, symbolName, sectionName, symbol, section,
-                             contentData, referenceStart, referenceEnd,
-                             referenceList) {}
+  template<typename... T>
+  ARMELFDefinedAtom(T&&... args)
+      : ELFDefinedAtom<ELFT>(std::forward<T>(args)...) {}
 
   bool isThumbFunc(const Elf_Sym *symbol) const {
     return symbol->getType() == llvm::ELF::STT_FUNC &&
         (static_cast<uint64_t>(symbol->st_value) & 0x1);
   }
 
   /// Correct st_value for symbols addressing Thumb instructions
   /// by removing its zero bit.

lib/ReaderWriter/ELF/Hexagon/HexagonELFFile.h

 template <class ELFT> class HexagonELFFile;
 
 template <class ELFT>
 class HexagonELFDefinedAtom : public ELFDefinedAtom<ELFT> {
   typedef llvm::object::Elf_Sym_Impl<ELFT> Elf_Sym;
   typedef llvm::object::Elf_Shdr_Impl<ELFT> Elf_Shdr;
 
 public:
-  HexagonELFDefinedAtom(const HexagonELFFile<ELFT> &file, StringRef symbolName,
-                        StringRef sectionName, const Elf_Sym *symbol,
-                        const Elf_Shdr *section, ArrayRef<uint8_t> contentData,
-                        unsigned int referenceStart, unsigned int referenceEnd,
-                        std::vector<ELFReference<ELFT> *> &referenceList)
-      : ELFDefinedAtom<ELFT>(file, symbolName, sectionName, symbol, section,
-                             contentData, referenceStart, referenceEnd,
-                             referenceList) {}
+  template<typename... T>
+  HexagonELFDefinedAtom(T&&... args)
+      : ELFDefinedAtom<ELFT>(std::forward<T>(args)...) {}
 
   virtual DefinedAtom::ContentType contentType() const {
     if (this->_contentType != DefinedAtom::typeUnknown)
       return this->_contentType;
     else if (this->_section->sh_flags & llvm::ELF::SHF_HEX_GPREL) {
       if (this->_section->sh_type == llvm::ELF::SHT_NOBITS)
         return (this->_contentType = DefinedAtom::typeZeroFillFast);
       else