This reverts commit c28ac75a87.
This change caused SEGV in the case like the following:
```
class C
class << self
attr_accessor :a
alias :const_missing :a=
end
end
p C::CONST
```
The common parts of `OP_SEND` and `OP_SUPER` have been merged so they no longer need to be independent.
This effectively means revert commit d0e8637e30.
In ISO30170, method_missing is defined under Kernel, but BasicObject is
introduced after ISO and we should move (and have moved) some Kernel
methods to BasicObject, e.g. instance_eval, equal?, etc.
We have missed method_missing (mostly because built-in method_missing
in VM handles most of the case).
When `cipush()` extends "callinfo", GC may occur.
In this case, there was a problem that prepared arguments were spoiled depending on the situation when `cipush()` is called.
Therefore, in the problematic part, `cipush()` is prepared first, and then the arguments are prepared.
The reason for passing `CINFO_DIRECT` to `cipush()` is that it is simply ignored in the `MRB_CATCH()` part of `mrb_vm_exec()`.
Also, the argument processing parts of `mrb_funcall_with_block()` and `mrb_yield_with_class()` are combined and made independent as `funcall_args_capture()`.
If GC occurs in `mrb_realloc()` in `ht_init()` called from `ar_set()`, the following inconsistency occurs:
- If `h_ht_on()` is called before `mrb_realloc()`, `hash->hsh.ht` is referenced instead of `hash->hsh.ea` during GC.
- If the pointer is changed by `ea_adjust()` in `ar_set()`, `hash->hsh.ea` (`hash->hsh.ht`) is referenced in GC before the change.
These modifications can be resolved by changing the order of processing.
However, if a `NoMemoryError` exception is raised, it is presumed that the size of the "AR" will be exceeded and the unintended state will continue.
To prevent this, elements should be added after they have been converted to "HT".
GC may occur in the `c->stbase = mrb_malloc()` part of the `fiber_init()` function.
The `SIGSEGV` happens because it references the `c->ci->stack` field without checking `c->ci`.
This is caused by #5272.
Exception raising can now be controlled by the caller.
The main purpose on this patch is:
- Suppress exceptions from `obj_free()` in `src/gc.c` with `mrb_env_unshare()`.
- Consider the possibility that calls to `mrb_malloc()` may cause `e` objects to be subject to GC.
When control is returned to `mrb_env_unshare()`, `struct free_obj::next` in the same offset as `struct REnv::stack` is rewritten.
Unexpected results then occur when the object is reused.
Also, if `mrb_heap_page` containing an `e` object is freed, it may cause `SIGSEGV` at that point.
- Protects the value of the stack on `callinfo` that just exits if GC occurs inside `mrb_env_unshare()`.
```ruby
def m
b = -> { b }
end
p m.call
# => print block object, not nil
```
This patch does not raise a `NoMemoryError` exception in `mrb_env_unshare()` and can detect that error.
Thus, the problem fixed in # 3087 is not resurrected.
Also, it may seem that this patch should suppress exceptions raised by `cipop()` during `mrb_protect_error()` and `mrb_vm_exec()` unwinds.
However, `mrb_callinfo::u.env` by `CINFO_DIRECT` is not seen to be set.
So in that case `mrb_env_unshare()` is assumed to be originally exception-free.
Yukihiro "Matz" Matsumoto