[llvm] [CommandLine] Better report unknown subcommands (PR #74811)

[James Henderson via llvm-commits]

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@@ -1687,21 +1705,24 @@ bool CommandLineParser::ParseCommandLineOptions(int argc,
     }
 
     if (!Handler) {
-      if (SinkOpts.empty()) {
+      if (!SinkOpts.empty()) {
+        for (Option *SinkOpt : SinkOpts)
+          SinkOpt->addOccurrence(i, "", StringRef(argv[i]));
+        continue;
+      } else if (i == 1 && !NearestSubCommandString.empty()) {
+        *Errs << ProgramName << ": Unknown subcommand '" << argv[i]
+              << "'.  Try: '" << argv[0] << " --help'\n"
+              << ProgramName << ": Did you mean '" << NearestSubCommandString
+              << "'?\n";
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jh7370 wrote:

It would be nice if you could avoid repeating most of the text from below here. I don't necessarily have a concrete sugestion, but perhaps creating a small helper function would be the way forward?

https://github.com/llvm/llvm-project/pull/74811