llvm dev - Apr 2019 - [CommandLine] Unable to implement a custom parser -- all marked final

https://llvm.org/docs/CommandLine.html#writing-a-custom-parser describes
how to implement a custom parser, but they're all marked `final`, so I
can't inherit.

Is there a reason for this?  If not, I'll submit patch with tests.

thanks...
don
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20190418/db418b9a/attachment.html>

Yeah, I think I did this a while back (& you're possibly not the only
one who's hit this - might be worth a search on llvm-dev for previous
threads).

If you check the commit history, I think my original motivation was
cleaning up the virtual dtor that wasn't used in LLVM by making the
base class's dtor protected, and the derived classes final.

It could be made virtual instead of protected/final - but without any
use in LLVM, I'm not sure it's worth exposing this extension point &
perhaps just updating the documentation is the best thing?

On Thu, Apr 18, 2019 at 1:45 PM Don Hinton via llvm-dev
<llvm-dev at lists.llvm.org> wrote:
>
> https://llvm.org/docs/CommandLine.html#writing-a-custom-parser describes
how to implement a custom parser, but they're all marked `final`, so I
can't inherit.
>
> Is there a reason for this?  If not, I'll submit patch with tests.
>
> thanks...
> don
>
>
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev

Hi David:

I'd actually like to use a custom parser in a tool I'm developing,
parsing
YAML files.  The partial fix for my purposes was:

--- a/llvm/include/llvm/Support/CommandLine.h
+++ b/llvm/include/llvm/Support/CommandLine.h
@@ -1044,7 +1044,7 @@ extern template class basic_parser<float>;
 //--------------------------------------------------
 // parser<std::string>
 //
-template <> class parser<std::string> final : public
basic_parser<std::string> {
+template <> class parser<std::string> : public
basic_parser<std::string> {
 public:
   parser(Option &O) : basic_parser(O) {}

@@ -1062,6 +1062,8 @@ public:

   // An out-of-line virtual method to provide a 'home' for this class.
   void anchor() override;
+
+  virtual ~parser() = default;
 };

If that's acceptable, I submit a patch.

thanks...
don

On Thu, Apr 18, 2019 at 1:56 PM David Blaikie <dblaikie at gmail.com>
wrote:
> Yeah, I think I did this a while back (& you're possibly not the
only
> one who's hit this - might be worth a search on llvm-dev for previous
> threads).
>
> If you check the commit history, I think my original motivation was
> cleaning up the virtual dtor that wasn't used in LLVM by making the
> base class's dtor protected, and the derived classes final.
>
> It could be made virtual instead of protected/final - but without any
> use in LLVM, I'm not sure it's worth exposing this extension point
&
> perhaps just updating the documentation is the best thing?
>
> On Thu, Apr 18, 2019 at 1:45 PM Don Hinton via llvm-dev
> <llvm-dev at lists.llvm.org> wrote:
> >
> > https://llvm.org/docs/CommandLine.html#writing-a-custom-parser
> describes how to implement a custom parser, but they're all marked
`final`,
> so I can't inherit.
> >
> > Is there a reason for this?  If not, I'll submit patch with tests.
> >
> > thanks...
> > don
> >
> >
> > _______________________________________________
> > LLVM Developers mailing list
> > llvm-dev at lists.llvm.org
> > https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20190418/c93ea4a5/attachment.html>