[llvm-commits] [llvm] r123717 - /llvm/trunk/lib/Support/CommandLine.cpp

[Chris Lattner]

On Jan 17, 2011, at 5:59 PM, Daniel Dunbar wrote:

> Author: ddunbar
> Date: Mon Jan 17 19:59:24 2011
> New Revision: 123717
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=123717&view=rev
> Log:
> Support/CommandLine: Add "Did you mean" print for mismatched operands.

Cool.  Will this dereference a null pointer when LookupNearestOption returns null?

-Chris

> 
> Modified:
>    llvm/trunk/lib/Support/CommandLine.cpp
> 
> Modified: llvm/trunk/lib/Support/CommandLine.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/CommandLine.cpp?rev=123717&r1=123716&r2=123717&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Support/CommandLine.cpp (original)
> +++ llvm/trunk/lib/Support/CommandLine.cpp Mon Jan 17 19:59:24 2011
> @@ -180,6 +180,34 @@
>   return I->second;
> }
> 
> +/// LookupNearestOption - Lookup the closest match to the option specified by
> +/// the specified option on the command line.  If there is a value specified
> +/// (after an equal sign) return that as well.  This assumes that leading dashes
> +/// have already been stripped.
> +static Option *LookupNearestOption(StringRef Arg,
> +                                   const StringMap<Option*> &OptionsMap) {
> +  // Reject all dashes.
> +  if (Arg.empty()) return 0;
> +
> +  // Split on any equal sign.
> +  StringRef LHS = Arg.split('=').first;
> +
> +  // Find the closest match.
> +  Option *Best = 0;
> +  unsigned BestDistance = 0;
> +  for (StringMap<Option*>::const_iterator it = OptionsMap.begin(),
> +         ie = OptionsMap.end(); it != ie; ++it) {
> +    unsigned Distance = StringRef(it->second->ArgStr).edit_distance(
> +      Arg, /*AllowReplacements=*/true, /*MaxEditDistance=*/BestDistance);
> +    if (!Best || Distance < BestDistance) {
> +      Best = it->second;
> +      BestDistance = Distance;
> +    }
> +  }
> +
> +  return Best;
> +}
> +
> /// CommaSeparateAndAddOccurence - A wrapper around Handler->addOccurence() that
> /// does special handling of cl::CommaSeparated options.
> static bool CommaSeparateAndAddOccurence(Option *Handler, unsigned pos,
> @@ -571,6 +599,7 @@
>   bool DashDashFound = false;  // Have we read '--'?
>   for (int i = 1; i < argc; ++i) {
>     Option *Handler = 0;
> +    Option *NearestHandler = 0;
>     StringRef Value;
>     StringRef ArgName = "";
> 
> @@ -644,12 +673,22 @@
>       if (Handler == 0)
>         Handler = HandlePrefixedOrGroupedOption(ArgName, Value,
>                                                 ErrorParsing, Opts);
> +
> +      // Otherwise, look for the closest available option to report to the user
> +      // in the upcoming error.
> +      if (Handler == 0 && SinkOpts.empty())
> +        NearestHandler = LookupNearestOption(ArgName, Opts);
>     }
> 
>     if (Handler == 0) {
>       if (SinkOpts.empty()) {
>         errs() << ProgramName << ": Unknown command line argument '"
>              << argv[i] << "'.  Try: '" << argv[0] << " -help'\n";
> +
> +        // If we know a near match, report it as well.
> +        errs() << ProgramName << ": Did you mean '-"
> +               << NearestHandler->ArgStr << "'?\n";
> +
>         ErrorParsing = true;
>       } else {
>         for (SmallVectorImpl<Option*>::iterator I = SinkOpts.begin(),
> 
> 
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