Runtime error when switching from 'M' error correction to 'H'

[zepplock]

If I switch code encode(Bin, 'M'). to encode(Bin, 'H'). in qrcode.erl.

I get this:

** (exit) an exception was raised:
    ** (FunctionClauseError) no function clause matching in :qrcode_matrix.encode_bits0/2
        (qrcode) src/qrcode_matrix.erl:169: :qrcode_matrix.encode_bits0([:d, :d, :d, :d, 0, 1, 0, 0, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 1, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 1, 1, 1, 1, 1, 1], <<0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 254, 0::size(1)>>)
        (qrcode) src/qrcode_matrix.erl:164: :qrcode_matrix.encode_bits/3
        (qrcode) src/qrcode_matrix.erl:53: :qrcode_matrix.finalize/5
        (qrcode) src/qrcode.erl:43: :qrcode.encode/2
        (qrcode) src/qrcode_png.erl:50: :qrcode_png.run/1
        (shoqr) web/controllers/v1/session_controller.ex:46: Shoqr.V1.SessionController.show_qr/2
        (shoqr) web/controllers/v1/session_controller.ex:11: Shoqr.V1.SessionController.phoenix_controller_pipeline/2
        (shoqr) lib/phoenix/router.ex:265: Shoqr.Router.dispatch/2
        (shoqr) web/router.ex:11: Shoqr.Router.do_call/2
        (shoqr) lib/shoqr/endpoint.ex:11: Shoqr.Endpoint.phoenix_pipeline/1
        (shoqr) lib/plug/debugger.ex:90: Shoqr.Endpoint."call (overridable 3)"/2
        (shoqr) lib/phoenix/endpoint/render_errors.ex:34: Shoqr.Endpoint.call/2
        (plug) lib/plug/adapters/cowboy/handler.ex:15: Plug.Adapters.Cowboy.Handler.upgrade/4
        (cowboy) src/cowboy_protocol.erl:442: :cowboy_protocol.execute/4

Note that switching to L or Q works fine.

[komone]

Root cause is incomplete padding of data for error correction blocks in qrcode module

[zepplock]

Thanks for looking into this Steve!

[komone]

Vlad -- do you have tests you could apply? -- I think this copes with all circumstances and passes my local testing

[zepplock]

This is issue is fixed. I can compile and generate QRs under all correction codes. Can be closed.