Panic in shortcodes when position arguemnts are supplied after named arguments.

[mdaffin]

I got the following panic when I forget to add a = to a shortcode call, this can be reproduced with the shortcode: {{ youtube(id="dQw4w9WgXcQ", autoplay) }}.

I would expect a nice error message rather than a hard panic in this situation.

This happens because you split on the arguments and assume they will have two parts inside parse_shortcode. But parse_shortcode does not return an error to elegantly handle the error case.

thread 'main' panicked at 'index out of bounds: the len is 1 but the index is 1', /checkout/src/liballoc/vec.rs:1551:10
stack backtrace:
   0: std::sys::imp::backtrace::tracing::imp::unwind_backtrace
             at /checkout/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::_print
             at /checkout/src/libstd/sys_common/backtrace.rs:68
   2: std::panicking::default_hook::{{closure}}
             at /checkout/src/libstd/sys_common/backtrace.rs:57
             at /checkout/src/libstd/panicking.rs:381
   3: std::panicking::default_hook
             at /checkout/src/libstd/panicking.rs:397
   4: std::panicking::rust_panic_with_hook
             at /checkout/src/libstd/panicking.rs:577
   5: std::panicking::begin_panic
             at /checkout/src/libstd/panicking.rs:538
   6: std::panicking::begin_panic_fmt
             at /checkout/src/libstd/panicking.rs:522
   7: rust_begin_unwind
             at /checkout/src/libstd/panicking.rs:498
   8: core::panicking::panic_fmt
             at /checkout/src/libcore/panicking.rs:71
   9: core::panicking::panic_bounds_check
             at /checkout/src/libcore/panicking.rs:58
  10: <alloc::vec::Vec<T> as core::ops::index::Index<usize>>::index
             at /checkout/src/liballoc/vec.rs:1551
  11: rendering::short_code::parse_shortcode
             at components/rendering/src/short_code.rs:59
  12: rendering::markdown::markdown_to_html::{{closure}}
             at components/rendering/src/markdown.rs:138
  13: core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &'a mut F>::call_once
             at /checkout/src/libcore/ops/function.rs:271
  14: <core::option::Option<T>>::map
             at /checkout/src/libcore/option.rs:398
  15: <core::iter::Map<I, F> as core::iter::iterator::Iterator>::next
             at /checkout/src/libcore/iter/mod.rs:1251
  16: <pulldown_cmark::html::Ctx<'b, I>>::run
             at /home/mdaffin/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/pulldown-cmark-0.1.0/src/html.rs:54
  17: pulldown_cmark::html::push_html
             at /home/mdaffin/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/pulldown-cmark-0.1.0/src/html.rs:283
  18: rendering::markdown::markdown_to_html
             at components/rendering/src/markdown.rs:290
  19: content::page::Page::render_markdown
             at components/content/src/page.rs:152
  20: site::Site::render_markdown::{{closure}}
             at components/site/src/lib.rs:248
  21: <rayon::iter::map::MapFolder<'f, C, F> as rayon::iter::plumbing::Folder<T>>::consume
             at /home/mdaffin/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/rayon-0.9.0/src/iter/map.rs:218
  22: rayon::iter::plumbing::Folder::consume_iter
             at /home/mdaffin/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/rayon-0.9.0/src/iter/plumbing.rs:84
  23: rayon::iter::plumbing::Producer::fold_with
             at /home/mdaffin/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/rayon-0.9.0/src/iter/plumbing.rs:48
  24: rayon::iter::plumbing::bridge_producer_consumer::helper
             at /home/mdaffin/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/rayon-0.9.0/src/iter/plumbing.rs:277
  25: rayon::iter::plumbing::bridge_producer_consumer
             at /home/mdaffin/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/rayon-0.9.0/src/iter/plumbing.rs:250
  26: <rayon::iter::plumbing::bridge::Callback<C> as rayon::iter::plumbing::ProducerCallback<I>>::callback
             at /home/mdaffin/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/rayon-0.9.0/src/iter/plumbing.rs:240
  27: <rayon::vec::IntoIter<T> as rayon::iter::IndexedParallelIterator>::with_producer
             at /home/mdaffin/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/rayon-0.9.0/src/vec.rs:63
  28: rayon::iter::plumbing::bridge
             at /home/mdaffin/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/rayon-0.9.0/src/iter/plumbing.rs:223
  29: <rayon::vec::IntoIter<T> as rayon::iter::ParallelIterator>::drive_unindexed
             at /home/mdaffin/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/rayon-0.9.0/src/vec.rs:30
  30: <rayon::collections::hash_map::IterMut<'a, K, V> as rayon::iter::ParallelIterator>::drive_unindexed
             at /home/mdaffin/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/rayon-0.9.0/src/delegate.rs:30
  31: <rayon::iter::map::Map<I, F> as rayon::iter::ParallelIterator>::drive_unindexed
             at /home/mdaffin/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/rayon-0.9.0/src/iter/map.rs:52
  32: <rayon::iter::fold::Fold<I, ID, F> as rayon::iter::ParallelIterator>::drive_unindexed
             at /home/mdaffin/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/rayon-0.9.0/src/iter/fold.rs:56
  33: rayon::iter::reduce::reduce
             at /home/mdaffin/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/rayon-0.9.0/src/iter/reduce.rs:14
  34: rayon::iter::ParallelIterator::reduce
             at /home/mdaffin/.cargo/registry/src/jackfan.us.kg-1ecc6299db9ec823/rayon-0.9.0/src/iter/mod.rs:353
  35: site::Site::render_markdown
             at components/site/src/lib.rs:245
  36: site::Site::load
             at components/site/src/lib.rs:220
  37: gutenberg::cmd::serve::create_new_site
             at src/cmd/serve.rs:96
  38: gutenberg::cmd::serve::serve
             at src/cmd/serve.rs:106
  39: gutenberg::main
             at src/main.rs:62
  40: __rust_maybe_catch_panic
             at /checkout/src/libpanic_unwind/lib.rs:101
  41: std::rt::lang_start
             at /checkout/src/libstd/panicking.rs:459
             at /checkout/src/libstd/panic.rs:365
             at /checkout/src/libstd/rt.rs:58
  42: main
  43: __libc_start_main
  44: _start

[Keats]

Woops.
The markdown rendering (including shortcodes, see #165) will be rewritten for the next major version which should be soonish, I'll add that to the test cases