[lld-macho] minimally handle option -dynamic

[gkm]

Summary

Stifle the warning for unimplemented option -dyamic, since it is already the default. Add Config::staticLink and skeletal support for altering the flag, but otherwise leave the option -static as hidden and its warning in place.

[int3]

lld/MachO/Driver.cpp

527

avoid auto

[gkm]

• s/auto/opt::Arg/

lld/MachO/Config.h

struct PlatformInfo {
   llvm::VersionTuple sdk;
 };
 
 struct Configuration {
   Symbol *entry;
   bool hasReexports = false;
   bool allLoad = false;
   bool forceLoadObjC = false;
+  bool staticLink = false;
   uint32_t headerPad;
   llvm::StringRef installName;
   llvm::StringRef outputFile;
   llvm::MachO::Architecture arch;
   PlatformInfo platform;
   llvm::MachO::HeaderFileType outputType;
   std::vector<llvm::StringRef> systemLibraryRoots;
   std::vector<llvm::StringRef> librarySearchPaths;

lld/MachO/Driver.cpp

bool macho::link(llvm::ArrayRef<const char *> argsArr, bool canExitEarly,
   config->entry = symtab->addUndefined(args.getLastArgValue(OPT_e, "_main"));
   config->outputFile = args.getLastArgValue(OPT_o, "a.out");
   config->installName =
       args.getLastArgValue(OPT_install_name, config->outputFile);
   config->headerPad = args::getHex(args, OPT_headerpad, /*Default=*/32);
   config->outputType = args.hasArg(OPT_dylib) ? MH_DYLIB : MH_EXECUTE;
   config->runtimePaths = args::getStrings(args, OPT_rpath);
   config->allLoad = args.hasArg(OPT_all_load);
 
+  if (const opt::Arg *arg = args.getLastArg(OPT_static, OPT_dynamic))
+    config->staticLink = (arg->getOption().getID() == OPT_static);
+
   std::vector<StringRef> &roots = config->systemLibraryRoots;
   for (const Arg *arg : args.filtered(OPT_syslibroot))
     roots.push_back(arg->getValue());
   // NOTE: the final `-syslibroot` being `/` will ignore all roots
   if (roots.size() && roots.back() == "/")
     roots.clear();
   // NOTE: roots can never be empty - add an empty root to simplify the library
   // and framework search path computation.
for (const auto &arg : args) {
     case OPT_headerpad:
     case OPT_install_name:
     case OPT_rpath:
     case OPT_sub_library:
     case OPT_Z:
     case OPT_arch:
     case OPT_syslibroot:
     case OPT_sectcreate:
+    case OPT_dynamic:
       // handled elsewhere
       break;
     default:
       warnIfUnimplementedOption(opt);
       break;
     }
   }
 

lld/MachO/Options.td

def r : Flag<["-"], "r">,
      Flags<[HelpHidden]>,
      Group<grp_kind>;
 def dylinker : Flag<["-"], "dylinker">,
      HelpText<"Produce a dylinker only used when building dyld">,
      Flags<[HelpHidden]>,
      Group<grp_kind>;
 def dynamic : Flag<["-"], "dynamic">,
      HelpText<"Link dynamically (default)">,
-     Flags<[HelpHidden]>,
      Group<grp_kind>;
 def static : Flag<["-"], "static">,
      HelpText<"Link statically">,
      Flags<[HelpHidden]>,
      Group<grp_kind>;
 def preload : Flag<["-"], "preload">,
      HelpText<"Produce an unsegmented binary for embedded systems">,
      Flags<[HelpHidden]>,