[gil] Duplicate typedef in pnm's scanline_read.hpp

[William Gallafent <william@…>]

At the top of the “scanline_reader” template in boost/gil/extension/io/formats/pnm/scanline_read.hpp the are the following lines of code:

…
private:

    typedef scanline_reader< Device
                           , pnm_tag
                           > this_t;

public:

    typedef pnm_tag tag_t;
    typedef reader_backend < Device, tag_t > backend_t;
    typedef scanline_reader< Device, tag_t > this_t;
…

This typdefs this_t twice, preventing compilation (using clang of Apple Xcode 5.1). Removing the first typedef fixes this problem.

[Mateusz Loskot]

GIL in Boost 1.68 delivers completely re-implemented I/O extensions. The new version does not include the duplicate definition, so the issue should be gone now.

Closing as fixed.

GitHub ref: ​https://github.com/boostorg/gil/projects/4#card-12375873