[dsymutil] Print warning/error for unknown/missing arguments.

After changing dsymutil to use libOption, we lost error reporting for
missing required arguments (input files). Additionally, we stopped
complaining about unknown arguments. This patch fixes both and adds a
test.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@375044 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit aa4a46afe84f5f3609fb3b44e7d79a4c3d1e1f25)

apple-llvm-split-commit: 4eb7e49ed665e6c93119f6c71d49b1c326cd1f61
apple-llvm-split-dir: llvm/

Author: JDevlieghere

llvm/test/tools/dsymutil/cmdline.test

@@ -26,3 +26,9 @@ HELP-NOT: -reverse-iterate
 
 RUN: dsymutil --version 2>&1 | FileCheck --check-prefix=VERSION %s
 VERSION: {{ version }}
+
+RUN: not dsymutil 2>&1 | FileCheck --check-prefix=NOINPUT %s
+NOINPUT: error: no input files specified
+
+RUN: dsymutil -bogus -help 2>&1 | FileCheck --check-prefix=BOGUS %s
+BOGUS: warning: ignoring unknown option: -bogus

llvm/tools/dsymutil/dsymutil.cpp

@@ -148,6 +148,11 @@ static Expected<std::vector<std::string>> getInputs(opt::InputArgList &Args,
 
 // Verify that the given combination of options makes sense.
 static Error verifyOptions(const DsymutilOptions &Options) {
+  if (Options.InputFiles.empty()) {
+    return make_error<StringError>("no input files specified",
+                                   errc::invalid_argument);
+  }
+
   if (Options.LinkOpts.Update &&
       std::find(Options.InputFiles.begin(), Options.InputFiles.end(), "-") !=
           Options.InputFiles.end()) {
@@ -440,6 +445,11 @@ int main(int argc, char **argv) {
   std::string SDKPath = sys::fs::getMainExecutable(argv[0], P);
   SDKPath = sys::path::parent_path(SDKPath);
 
+  for (auto *Arg : Args.filtered(OPT_UNKNOWN)) {
+    WithColor::warning() << "ignoring unknown option: " << Arg->getSpelling()
+                         << '\n';
+  }
+
   if (Args.hasArg(OPT_help)) {
     T.PrintHelp(
         outs(), (std::string(argv[0]) + " [options] <input files>").c_str(),