Unlike method definition, constant reference should start from
`MRB_PROC_TARGET_CLASS(ci->proc)`, not `ci->target_class`.
In addition, `MRB_PROC_TARGET_CLASS(ci->proc)` is always set.
Instead of `irep` links, we added a `upper` link to `struct RProc`.
To make a space for the `upper` link, we moved `target_class` reference.
If a `Proc` does not have `env`, `target_class` is saved in an `union`
shared with `env` (if a `Proc` has env, you can tell it by `MRB_PROC_ENV_P()).
Otherwise `target_class` is referenced from `env->c`. We removed links
in `env` as well.
This change removes 2 members from `mrb_irep` struct, thus saving 2
words per method/proc/block. This also fixes potential memory leaks
due to the circular references caused by a link from `mrb_irep`.
Instead of `irep -> proc` chain, we use `irep -> irep` chain to
avoid GC bugs like #3804. We added `target_class` reference to
`mrb_irep` struct. That means one more word consumption per `irep`.
For performance reason. Segmented list consumes slightly less memory
but takes a lot of time especially when there are many slots in the
segment lists (e.g. class constants).
The change removes several internal instance variables used by
class name management. The variables `__classid__` and `__classpath__`
are no longer available. `__outer__` is used only for unnamed outer
classes/modules (and will be removed after they are named).
[Important note]
Along with this change we removed several public functions.
- mrb_class_outer_module()
- mrb_class_sym()
We believe no one have used those functions, but if you do, please
ask us for the workaround.
If the argument is always a string, then mrb_str_cat_str() can be
directly called instead of indirectly by mrb_str_append().
mrb_any_to_s(), mrb_obj_as_string(), mrb_inspect() always return a
string.
Dr Markus Kuhn published in 1999 an article [1] explaining in details
why we shouldn't use the ASCII grave accent (0x60) as a left quotation.
Backticks have been used most notably to produce nice-looking LaTeX
documents but it doesn't seem to be an issue on modern platforms and
for the oldest ones, there are workarounds as mentioned by Dr Kuhn.
[1]: https://www.cl.cam.ac.uk/~mgk25/ucs/quotes.html
Ukrainskiy Sergey