[LLD][ELF] - Use LLVM_ELF_IMPORT_TYPES_ELFT macro instead of multiple types definitions. NFCI.

[grimar]

Summary

We can reduce the number of "using" declarations.
LLVM_ELF_IMPORT_TYPES_ELFT was extended in D93801.

[MaskRay]

LGTM.

[grimar]

I had to revert the change in SharedFile::parse() before commit, because of warnings reported by GCC:

LLVM/llvm-project/llvm/include/llvm/Object/ELFTypes.h:136:50: warning: typedef ‘using Elf_Relr_Range = typename ELFT::RelrRange’ locally defined but not used [-Wunused-local-typedefs]
   using Elf_Relr_Range = typename ELFT::RelrRange;

lld/ELF/InputFiles.h

protected:
   const void *elfSyms = nullptr;
   size_t numELFSyms = 0;
   uint32_t firstGlobal = 0;
   StringRef stringTable;
 };
 
 // .o file.
 template <class ELFT> class ObjFile : public ELFFileBase {
-  using Elf_Rel = typename ELFT::Rel;
-  using Elf_Rela = typename ELFT::Rela;
-  using Elf_Sym = typename ELFT::Sym;
-  using Elf_Shdr = typename ELFT::Shdr;
-  using Elf_Word = typename ELFT::Word;
-  using Elf_CGProfile = typename ELFT::CGProfile;
+  LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
 
 public:
   static bool classof(const InputFile *f) { return f->kind() == ObjKind; }
 
   llvm::object::ELFFile<ELFT> getObj() const {
     return this->ELFFileBase::getObj<ELFT>();
   }
 

lld/ELF/InputFiles.cpp

 // The special index 0 is reserved for VERF_NDX_LOCAL and 1 is for
 // VER_NDX_GLOBAL. There's no table entry for these special versions in
 // ".gnu.version_d".
 //
 // The file format for symbol versioning is perhaps a bit more complicated
 // than necessary, but you can easily understand the code if you wrap your
 // head around the data structure described above.
 template <class ELFT> void SharedFile::parse() {
-  using Elf_Dyn = typename ELFT::Dyn;
-  using Elf_Shdr = typename ELFT::Shdr;
-  using Elf_Sym = typename ELFT::Sym;
-  using Elf_Verdef = typename ELFT::Verdef;
-  using Elf_Versym = typename ELFT::Versym;
+  LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
 
   ArrayRef<Elf_Dyn> dynamicTags;
   const ELFFile<ELFT> obj = this->getObj<ELFT>();
   ArrayRef<Elf_Shdr> sections = CHECK(obj.sections(), this);
 
   const Elf_Shdr *versymSec = nullptr;
   const Elf_Shdr *verdefSec = nullptr;
   const Elf_Shdr *verneedSec = nullptr;

lld/ELF/SyntheticSections.h

public:
   // load address. This means we need to write the symbol virtual address
   // plus the original addend as the final relocation addend.
   bool useSymVA;
   int64_t addend;
   const OutputSection *outputSec;
 };
 
 template <class ELFT> class DynamicSection final : public SyntheticSection {
-  using Elf_Dyn = typename ELFT::Dyn;
-  using Elf_Rel = typename ELFT::Rel;
-  using Elf_Rela = typename ELFT::Rela;
-  using Elf_Relr = typename ELFT::Relr;
-  using Elf_Shdr = typename ELFT::Shdr;
-  using Elf_Sym = typename ELFT::Sym;
+  LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
 
   // finalizeContents() fills this vector with the section contents.
   std::vector<std::pair<int32_t, std::function<uint64_t()>>> entries;
 
 public:
   DynamicSection();
   void finalizeContents() override;
   void writeTo(uint8_t *buf) override;

lld/ELF/Writer.cpp

 using namespace llvm::support::endian;
 using namespace lld;
 using namespace lld::elf;
 
 namespace {
 // The writer writes a SymbolTable result to a file.
 template <class ELFT> class Writer {
 public:
+  LLVM_ELF_IMPORT_TYPES_ELFT(ELFT)
+
   Writer() : buffer(errorHandler().outputBuffer) {}
-  using Elf_Shdr = typename ELFT::Shdr;
-  using Elf_Ehdr = typename ELFT::Ehdr;
-  using Elf_Phdr = typename ELFT::Phdr;
 
   void run();
 
 private:
   void copyLocalSymbols();
   void addSectionSymbols();
   void forEachRelSec(llvm::function_ref<void(InputSectionBase &)> fn);
   void sortSections();