Singleton class definition do not introduce its own class variable scope
in CRuby/JRuby. So should mruby.
```
module Mod1
class << Object.new
C = 1
@@cv = 1
p Module.nesting, # => [#<Class:#<Object:0x55cb16e60a50>>, Mod1]
constants, # => [:C]
class_variables, # => []
Mod1.class_variables # => [:@@cv]
end
end
```
We needed to preserve the original method name somewhere. We kept it in
the `env` structure pointed from aliased methods. #1457 and #1531 tried
to address this issue. But this patch is more memory efficient.
Limitation: this fix does not support `super` from methods defined by
`define_method`. This limitation may be addressed in the future, but
it's low priority.
Before this patch:
$ bin/mruby -e 'p 3.to_s(2)'
trace (most recent call last):
[0] -e:1
-e:1: 'to_s': wrong number of arguments (1 for 0) (ArgumentError)
After this patch:
$ bin/mruby -e 'p 3.to_s(2)'
"11"
In terms of specifiers, argv is never referenced after a method call as
shown in #3090.
Reduction of object code can be expected.
If you need to refer to argv after a method call in the same loop,
update argv after the method call.
1. `$/` and other Perl-ish global variables are not defined in ISO.
2. The current Ruby policy do not encourage those variables.
3. Those variables has global effect and can cause troubles.
Unlike CRuby, there's no way to process strings byte-wise by core
methods because there's no per string encoding in mruby, so that
we moved 3 byte-wise operation methods from `mruby-string-ext` gem.
Prioritize embedded string in the following functions:
- `str_new_static`
- `str_new`
- `mrb_str_new_capa`
- `mrb_str_pool`
The reasons are as follows:
- Consistency with `mrb_str_byte_subseq` and `str_replace`.
- Memory locality increases and may be slightly faster.
- No conversion cost to embedded string when modifying the string.
On 64-bit CPU, there is padding in `RBasic`, so reorder the fields and use
it as buffer of embedded string. This change allows 4 more bytes to be
embedded on 64-bit CPU.
However, an incompatibility will occur if `RString::as::ary` is accessed
directly because `RString` structure has changed.
- `mrb_str_index_m()` and `mrb_str_rindex()`
Make `mrb_get_args()` called only once from called twice.
- `mrb_str_byteslice()`
Replace `goto` with `if ~ else`.
Previously `String#rindex` returned the wrong index when given an
invalid UTF-8 string.
```terminal
% ruby26 -e 'str = "\xf0☀\xf1☁\xf2☂\xf3☃\xf0☀\xf1☁\xf2☂\xf3☃"; p str.rindex("☁")'
11
% ./mruby-head -e 'str = "\xf0☀\xf1☁\xf2☂\xf3☃\xf0☀\xf1☁\xf2☂\xf3☃"; p str.rindex("☁")'
nil
% ./mruby-patched -e 'str = "\xf0☀\xf1☁\xf2☂\xf3☃\xf0☀\xf1☁\xf2☂\xf3☃"; p str.rindex("☁")'
11
```
Yukihiro "Matz" Matsumoto