A copied Proc now always carries `MRB_PROC_ORPHAN`, so calling a
`dup`'d block that contains `break` or `return` raises
`LocalJumpError` even while the original yielding method is still on
the stack.
This is stricter than CRuby — which only marks the copy orphan once
the original yielding method returns — but matches mruby's
memory-first design: tracking the original via a back pointer in
RProc would also enlarge the GC mark set. dearblue's option (1) in
the linked issue, accepted for the simpler RProc layout.
Document the divergence in `doc/limitations.md` and add a regression
test in `test/t/proc.rb`.
close#6345
Co-authored-by: Claude <noreply@anthropic.com>
Previously, the identity of the proc object was verified solely based on the identity of irep.
This patch makes the behavior consistent with CRuby.
The reason I noticed this issue was that when adding multiple proc objects with the same irep to a set object, only one was added.
```ruby
p Set.new(Array.new(3) { -> {} }).size
# => 3 (Ruby 4.0)
# => 1 (mruby without this patch)
```
If the block scope is the same, there is only one in CRuby as well.
However, in CRuby, the result of `Proc#to_s` is not affected by the block scope, so it has been changed to be based on the object's address.
The reason no test for `Proc#to_s` was added is that I couldn't determine whether it should be based on `Proc#hash` or the object's address.
```ruby
b = []
t = 3
while t > 0
b << -> {}
t -= 1
end
p Set.new(b).size
# => 1 (Ruby 4.0 and mruby)
p b[0].to_s == b[1].to_s
# => false (Ruby 4.0)
# => true (mruby without this patch)
```
From the CRuby 2.2.2 Proc#arity documentation:
If the block has optional arguments, returns -n-1, where n is the number
of mandatory arguments, with the exception for blocks that are not
lambdas and have only a finite number of optional arguments; in this
latter case, returns n.
Yukihiro "Matz" Matsumoto