This flag means all the characters in the string can be represented by a
single byte, i.e., the string does not contain any multi-byte character.
Those characters are likely ASCII characters, but may be a part of broken
UTF-8 sequence, so the term 'ASCII' is not sufficient.
Instead of its own version of quick search, now we use str_index_str()
and adjust character position. This change makes searching 4 times
faster in some cases; ref #6143
Current code scan the string twice (once from RSTRING_CHAR_LEN, and once
from chars2bytes), but those scans are not necessary. Just point the end
of the string.
The restriction was introduced in commit b563bcb7ff to resolve https://github.com/mruby/mruby/issues/3462.
Subsequently, the `RBreak` object, introduced by mruby 1.3.0, allowed crossing the C boundary.
```ruby
def cross; Class.new { proc { return }.call }; end; cross
# => unexpected return (LocalJumpError) # without this patch
# => nothing raised # with this patch
```
If `Class#allocate` is prohibited, subclasses should also be implicitly prohibited.
```ruby
p Class.new(Struct).allocate.class
# => #<Class:0x82362ac00> by #6122
# => allocator undefined for #<Class:0x000000083a983220> (TypeError) by Ruby 3.2
```
Added `MRB_DEFINE_ALLOCATOR()` to allow subclasses to use `Class#allocate`.
Supplement to #6122.
The method introduced by #5979 causes a fault by swapping classes.
```console
% bin/mruby -e 'Method = Proc; p Object.method(:inspect)'
zsh: segmentation fault (core dumped) bin/mruby -e 'Method = Proc; p Object.method(:inspect)'
```
After applying this patch, a `TypeError` exception will be raised.
```console
% bin/mruby -e 'Method = Proc; p Object.method(:inspect)'
trace (most recent call last):
[1] -e:1
-e:1:in method: allocation failure of Proc (TypeError)
```
However, if the `mrb_vtype` is the same object, the same care must still be taken as before.
```console
% bin/mruby -e 'Method = Binding; p method(:puts).eval("12345")'
trace (most recent call last):
[1] -e:1
-e:1:in eval: wrong argument type nil (expected Proc) (TypeError)
```
It is now possible to specify return destination directly.
This allows callinfo to distinguish between calls to the same proc object.
At the same time, the `Kernel#catch` method is adjusted.
By removing the previously required double lambda object, the REnv object is no longer created as well.
When a fiber switched by `Fiber.yield` is resumed by `Fiber#resume` by C, it is necessary to pop CI with `fiber_switch()`.
Previously, CI misalignment caused inconsistencies, including crashes, on the next `Fiber#resume`.
dearblue