[cfe-dev] Help with Command-Line Validation

[Uri Mann via cfe-dev]

Hi Dave;

Thanks for your help. I changed my code per your suggestion. I’m not sure if you’re the author of the code or you’re just maintaining the docs, but there’s a small change which I added, to make the derived class compile:
struct ProjectParser : public llvm::cl::basic_parser<std::string> {
    ProjectParser(__in llvm::cl::opt<std::string, false, ProjectParser>& Option);
    ProjectParser& operator=(const ProjectParser&) = delete;

    typedef std::string parser_data_type;
    typedef llvm::cl::OptionValue<std::string> OptVal;

    bool parse(__in llvm::cl::Option& option,
               __in llvm::StringRef argName,
               __in const std::string& argValue,
               __in std::string& project);
    // Needed to for CLANG 3.7.0
    operator llvm::cl::parser<std::string>&(void) const;
};

I had to add the conversion operator since template<class ParserClass, class ValDT> void printOptionDiff() methods expects llvm::cl::parser<std::string>. In my case the conversion operator never gets called. If the above method is called, it may try to access members which do not exists.

Thanks again.
-Uri


From: David Blaikie [mailto:dblaikie at gmail.com] 
Sent: Tuesday, November 24, 2015 9:40 AM
To: Uri Mann
Cc: cfe-dev at lists.llvm.org
Subject: Re: [cfe-dev] Help with Command-Line Validation



On Tue, Nov 24, 2015 at 8:47 AM, Uri Mann via cfe-dev <cfe-dev at lists.llvm.org> wrote:
I’m updating from CLANG 3.5.0 to 3.7.0. In the 3.5.0 version I have a std::string option with validation.
struct ProjectParser : public llvm::cl::parser<std::string> {
    bool parse(llvm::cl::Option& option,
                          llvm::StringRef argName,
                          const std::string& argValue,
                          std::string& project);
};
 
llvm::cl::opt<std::string, false, ProjectParser> Project;
 
This no longer compiles since the llvm::cl::parser<std::string> template was specialized and made ‘final’. The docs don’t address this issue.

Sorry about that - I've an open bug telling me I need to update the docs here. I made the change to make parser final (bunch of API design reasons and that extension point wasn't needed inside LLVM/Clang - though I didn't realize we documented it as an extension point for external users)

I'm not quite sure why we documented this as a useful extension point for external users yet have no examples of using that inside the LLVM project - I imagine we do something else inside LLVM instead.

Off the cuff, I would suggest you derived from basic_parser and add the two member typedefs that parser<T> was providing for you. (but I'm still curious what LLVM does if it doesn't do the derivation from parser<T> and whether we should understand/encourage that instead)

- Dave
 
 
Any help will be appreciated. Thanks in advance.
-Uri
 

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