```console
% for rb in `git ls-files '*/mrblib/*.rb' 'mrblib'`; do ruby30 -cw $rb > /dev/null; done
mrbgems/mruby-array-ext/mrblib/array.rb:389: warning: assigned but unused variable - ary
mrbgems/mruby-array-ext/mrblib/array.rb:663: warning: assigned but unused variable - len
mrbgems/mruby-hash-ext/mrblib/hash.rb:119: warning: possibly useless use of a variable in void context
mrbgems/mruby-hash-ext/mrblib/hash.rb:259: warning: assigned but unused variable - keys
mrbgems/mruby-io/mrblib/io.rb:229: warning: literal in condition
mrbgems/mruby-io/mrblib/io.rb:280: warning: literal in condition
mrbgems/mruby-string-ext/mrblib/string.rb:347: warning: assigned but unused variable - len
mrbgems/mruby-toplevel-ext/mrblib/toplevel.rb:2: warning: parentheses after method name is interpreted as an argument list, not a decomposed argument
```
We assume meta-programming is less used in embedded environments.
We have moved following methods:
* Kernel module
global_variables, local_variables, singleton_class,
instance_variables, instance_variables_defined?, instance_variable_get,
instance_variable_set, methods, private_methods, public_methods,
protected_methods, singleton_methods, define_singleton_methods
* Module class
class_variables, class_variables_defined?, class_variable_get,
class_variable_set, remove_class_variable, included_modules,
instance_methods, remove_method, method_removed, constants
* Module class methods
constants, nesting
Note:
Following meta-programming methods are kept in the core:
* Module class
alias_method, undef_method, ancestors, const_defined?, const_get,
const_set, remove_const, method_defined?, define_method
* Toplevel object
define_method
`mruby-metaprog` gem is linked by default (specified in default.gembox).
When it is removed, it will save 40KB (stripped:8KB) on x86-64
environment last time I measured.