Report an error if a CLI option lacks an argument

[llunak]

Summary

Without this, e.g. "lldb -p $(pidof process)" simply starts if there's no process.
Code pretty much copied from Clang's CompilerInvocation::CreateFromArgs().

[JDevlieghere]

Thanks for fixing this. I do have a few comments but the logic looks good.

lldb/test/Shell/Driver/TestError.test

2

Since there's only one prefix to check you can omit --check-prefix ARGMISSING and just use CHECK as the prefix on the next line.

lldb/tools/driver/Driver.cpp

873

Let's move this and the next line out of check here and below the check for unknown options, so that the user gets to see both errors at once. That way we also don't have to duplicate the error message.

[llunak]

Adjusted according to the comments.

[JDevlieghere]

Thanks! LGTM

lldb/test/Shell/Driver/TestError.test

+RUN: not %lldb --arch 2>&1 | FileCheck %s
+CHECK: error: argument to '--arch' is missing

lldb/tools/driver/Driver.cpp

 
 int main(int argc, char const *argv[]) {
   // Setup LLVM signal handlers and make sure we call llvm_shutdown() on
   // destruction.
   llvm::InitLLVM IL(argc, argv, /*InstallPipeSignalExitHandler=*/false);
 
   // Parse arguments.
   LLDBOptTable T;
-  unsigned MAI;
-  unsigned MAC;
+  unsigned MissingArgIndex;
+  unsigned MissingArgCount;
   ArrayRef<const char *> arg_arr = makeArrayRef(argv + 1, argc - 1);
-  opt::InputArgList input_args = T.ParseArgs(arg_arr, MAI, MAC);
+  opt::InputArgList input_args =
+      T.ParseArgs(arg_arr, MissingArgIndex, MissingArgCount);
   llvm::StringRef argv0 = llvm::sys::path::filename(argv[0]);
 
   if (input_args.hasArg(OPT_help)) {
     printHelp(T, argv0);
     return 0;
   }
 
+  // Check for missing argument error.
+  if (MissingArgCount) {
+    WithColor::error() << "argument to '"
+                       << input_args.getArgString(MissingArgIndex)
+                       << "' is missing\n";
+  }
   // Error out on unknown options.
   if (input_args.hasArg(OPT_UNKNOWN)) {
     for (auto *arg : input_args.filtered(OPT_UNKNOWN)) {
       WithColor::error() << "unknown option: " << arg->getSpelling() << '\n';
     }
+  }
+  if (MissingArgCount || input_args.hasArg(OPT_UNKNOWN)) {
     llvm::errs() << "Use '" << argv0
                  << " --help' for a complete list of options.\n";
     return 1;
   }
 
   if (auto exit_code = InitializeReproducer(argv[0], input_args)) {
     return *exit_code;
   }