Users can now switch to their own implementation of GEM.
However, we do not guarantee that this will not be a problem in the current situation.
This may need to be improved in the future.
This was the cause of the command line flag being affected by changes in the parent build.
So, for example, if `mruby-rational` was included, even the automatically added `mrbc` builds included `MRB_USE_RATIONAL`.
At the same time, the saving and restoration of unwanted object arenas was removed.
In addition, the common code to extend the pool that existed before has been grouped together and newly established as `lit_pool_extend()`.
Note that previously the variable `i` was updated at that time, but since it is the same as the value at the end of a `for` statement, it has been omitted.
The original catalyst was that `bin/mrbc` with the `MRB_WORD_BOXING` + not `MRB_BOXWORD_NO_FLOAT_TRUNCATE` configuration caused `bin/mrbtest` with the `MRB_NO_BOXING` configuration to fail.
Upon investigation, I concluded that avoiding the creation of temporary objects would prevent the truncation of floating point numbers.
Therefore, this patch also prevents the `rake test` from failing with the following configuration.
```console
% cat test_config.rb
bootstrap_mrbc = nil
MRuby::Build.new do |conf|
conf.toolchain
conf.enable_debug
conf.enable_test
conf.disable_presym
conf.defines << %w(MRB_WORD_BOXING)
#conf.defines << %w(MRB_WORDBOX_NO_FLOAT_TRUNCATE)
gem core: "mruby-bin-mrbc"
gem core: "mruby-kernel-ext"
bootstrap_mrbc = File.join(conf.build_dir, "bin/mrbc")
end
MRuby::Build.new("nobox") do |conf|
conf.toolchain
conf.enable_debug
conf.enable_test
conf.defines << %(MRB_NO_BOXING)
conf.mrbcfile = bootstrap_mrbc
gem core: "mruby-kernel-ext"
end
```
Normal return of control from the `mrb_sys_fail()` function has unexpected results.
Example: double free, malloc with huge size used as error integer
The following is an example of an actual crash:
```console
% cat crash.rb
def SystemCallError._sys_fail(*a)
nil
end
File.readlink("/404")
% bin/mruby crash.rb
zsh: segmentation fault (core dumped) bin/mruby crash.rb
```
dearblue