Allow use of -list-checks option without need to pass source files.

[hintonda]

Summary

Initialize CommonOptionsParser with ZeroOrOne NumOccurrenceFlag so callers can pass -list-checks without the need to pass additional positional parameters, then add dummy file if none were supplied.

[alexfh]

Looks good with a couple of nits. I'll fix them and submit the patch for you. Thanks for fixing this!

clang-tidy/tool/ClangTidyMain.cpp

265

Looks like it exceeds the 80-column limit.

271

This should be a StringRef and there should be no space before the parenthesis.

[alexfh]

clang-tidy/tool/ClangTidyMain.cpp

274

clang-tidy should also error out when no positional arguments are specified and no -list-checks. Will fix that as well.

[alexfh]

Fixed the issues and committed as revision 245205.

Thanks for the fix!

clang-tidy/tool/ClangTidyMain.cpp

272

s/pathlist/PathList/g

[hintonda]

Great, thanks Alex...

clang-tidy/tool/ClangTidyMain.cpp

if (llvm::ErrorOr<ClangTidyOptions> ParsedConfig =
       return nullptr;
     }
   }
   return llvm::make_unique<FileOptionsProvider>(GlobalOptions, DefaultOptions,
                                                 OverrideOptions);
 }
 
 static int clangTidyMain(int argc, const char **argv) {
-  CommonOptionsParser OptionsParser(argc, argv, ClangTidyCategory);
+  CommonOptionsParser OptionsParser(argc, argv, ClangTidyCategory, cl::ZeroOrMore);
 
   auto OptionsProvider = createOptionsProvider();
   if (!OptionsProvider)
     return 1;
 
-  std::string FileName = OptionsParser.getSourcePathList().front();
+  std::string FileName ("dummy.cpp");
+  auto pathlist = OptionsParser.getSourcePathList();
+  if (!pathlist.empty()) {
+    FileName = OptionsParser.getSourcePathList().front();
+  }
   ClangTidyOptions EffectiveOptions = OptionsProvider->getOptions(FileName);
   std::vector<std::string> EnabledChecks = getCheckNames(EffectiveOptions);
 
-  // FIXME: Allow using --list-checks without positional arguments.
   if (ListChecks) {
     llvm::outs() << "Enabled checks:";
     for (auto CheckName : EnabledChecks)
       llvm::outs() << "\n    " << CheckName;
     llvm::outs() << "\n\n";
     return 0;
   }