Improve error message for an unknown --plugin-opt.

[ruiu]

Summary

Before:

$ ld.lld --plugin-opt=-foo
ld.lld: --Unknown command line argument '-abc'

After:

$ ld.lld --plugin-opt=-foo
ld.lld: --plugin-opt: ld.lld --Unknown command line argument '-abc'

[grimar]

LGTM. Thanks!

lld/ELF/Driver.cpp

609

I would probably add ...,/*Overview=*/"", ...) as I had to look what this parameter is.

[ruiu]

lld/ELF/Driver.cpp

609

I honestly don't think that's helpful because we don't explain what is "Overview" after all (and even I don't know what it is.)

lld/ELF/Driver.cpp

static std::vector<StringRef> getSymbolOrderingFile(MemoryBufferRef MB) {
   SetVector<StringRef> Names;
   for (StringRef S : args::getLines(MB))
     if (!Names.insert(S) && Config->WarnSymbolOrdering)
       warn(MB.getBufferIdentifier() + ": duplicate ordered symbol: " + S);
 
   return Names.takeVector();
 }
 
+static void parseClangOption(StringRef Opt, const Twine &Msg) {
+  std::string Err;
+  raw_string_ostream OS(Err);
+
+  const char *Argv[] = {Config->ProgName.data(), Opt.data()};
+  if (cl::ParseCommandLineOptions(2, Argv, "", &OS))
+    return;
+  OS.flush();
+  error(Msg + ": " + StringRef(Err).trim());
+}
+
 // Initializes Config members by the command line options.
 void LinkerDriver::readConfigs(opt::InputArgList &Args) {
   errorHandler().Verbose = Args.hasArg(OPT_verbose);
   errorHandler().FatalWarnings =
       Args.hasFlag(OPT_fatal_warnings, OPT_no_fatal_warnings, false);
 
   Config->AllowMultipleDefinition =
       Args.hasFlag(OPT_allow_multiple_definition,
void LinkerDriver::readConfigs(opt::InputArgList &Args) {
   Config->ZRelro = !hasZOption(Args, "norelro");
   Config->ZRetpolineplt = hasZOption(Args, "retpolineplt");
   Config->ZRodynamic = hasZOption(Args, "rodynamic");
   Config->ZStackSize = args::getZOptionValue(Args, OPT_z, "stack-size", 0);
   Config->ZText = !hasZOption(Args, "notext");
   Config->ZWxneeded = hasZOption(Args, "wxneeded");
 
   // Parse LTO plugin-related options for compatibility with gold.
-  std::vector<const char *> LTOOptions({Config->ProgName.data()});
   for (auto *Arg : Args.filtered(OPT_plugin_opt)) {
     StringRef S = Arg->getValue();
     if (S == "disable-verify")
       Config->DisableVerify = true;
     else if (S == "save-temps")
       Config->SaveTemps = true;
     else if (S.startswith("O"))
       Config->LTOO = parseInt(S.substr(1), Arg);
     else if (S.startswith("lto-partitions="))
       Config->LTOPartitions = parseInt(S.substr(15), Arg);
     else if (S.startswith("jobs="))
       Config->ThinLTOJobs = parseInt(S.substr(5), Arg);
     else if (S.startswith("mcpu="))
-      LTOOptions.push_back(Saver.save("-" + S).data());
+      parseClangOption(Saver.save("-" + S), Arg->getSpelling());
     else if (!S.startswith("/") && !S.startswith("-fresolution=") &&
              !S.startswith("-pass-through=") && !S.startswith("thinlto"))
-      LTOOptions.push_back(S.data());
+      parseClangOption(S, Arg->getSpelling());
   }
-  // Parse and evaluate -mllvm options.
+
+  // Parse -mllvm options.
   for (auto *Arg : Args.filtered(OPT_mllvm))
-    LTOOptions.push_back(Arg->getValue());
-  cl::ParseCommandLineOptions(LTOOptions.size(), LTOOptions.data());
+    parseClangOption(Arg->getValue(), Arg->getSpelling());
 
   if (Config->LTOO > 3)
     error("invalid optimization level for LTO: " + Twine(Config->LTOO));
   if (Config->LTOPartitions == 0)
     error("--lto-partitions: number of threads must be > 0");
   if (Config->ThinLTOJobs == 0)
     error("--thinlto-jobs: number of threads must be > 0");
 

lld/test/ELF/lto-plugin-ignore.s

 # REQUIRES: x86
 
 # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t
 # RUN: ld.lld %t -plugin-opt=/foo/bar -plugin-opt=-fresolution=zed \
 # RUN:   -plugin-opt=-pass-through=-lgcc -plugin-opt=-function-sections \
 # RUN:   -plugin-opt=-data-sections -plugin-opt=thinlto -o /dev/null
 
-# RUN: not ld.lld %t -plugin-opt=-data-sectionxxx \
-# RUN:   -plugin-opt=-function-sectionxxx 2>&1 | FileCheck %s
-# CHECK: Unknown command line argument '-data-sectionxxx'
-# CHECK: Unknown command line argument '-function-sectionxxx'
+# RUN: not ld.lld %t -plugin-opt=-abc -plugin-opt=-xyz 2>&1 | FileCheck %s
+# CHECK: --plugin-opt: Unknown command line argument '-abc'
+# CHECK: --plugin-opt: Unknown command line argument '-xyz'