Calling the `Method#{parameters,source_location}` method on a static `Proc` object resulted in `SIGSEGV`.
The trigger is https://github.com/mruby/mruby/pull/5402.
The original implementation of the `Method#{parameters,source_location}` method was to temporarily rewrite the object and then call the method of the same name in `Proc`.
Rewriting of objects placed in the ROM section by #5402 above is prohibited by hardware such as the CPU.
This caused a `SIGSEGV`.
If a splat argument was passed, it could write out of range on the VM stack.
```console
% bin/mruby -e 'def m(*args, **opts, &blk) p [args, opts, blk] end; m(*%w(X Y Z), r: 1, g: 2, b: 3) {}'
[["X", "Y", "Z"], {}, #<Proc:0x80077d7d0>]
```
```console
% c++ -xc++ -std=c++03 -S -Iinclude -DMRB_NAN_BOXING -DMRB_NO_PRESYM -o- src/array.c > /dev/null
In file included from src/array.c:7:
In file included from include/mruby.h:115:
In file included from include/mruby/value.h:201:
include/mruby/boxing_nan.h:95:12: error: cannot initialize return object of type 'enum mrb_vtype' with an rvalue of type 'int'
return (enum mrb_vtype)(o.u >> 8) & 0x1f;
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
1 error generated.
```
ref: #5564
```console
% cc -pedantic -S -Iinclude -DMRB_NO_PRESYM -o- src/array.c > /dev/null
In file included from src/array.c:7:
In file included from include/mruby.h:115:
In file included from include/mruby/value.h:204:
include/mruby/boxing_word.h:133:1: warning: must specify at least one argument for '...' parameter of variadic macro [-Wgnu-zero-variadic-macro-arguments]
mrb_static_assert(sizeof(mrb_value) == sizeof(union mrb_value_));
^
include/mruby.h:109:108: note: expanded from macro 'mrb_static_assert'
mrb_static_assert_expand(mrb_static_assert_selector(__VA_ARGS__, mrb_static_assert2, mrb_static_assert1)(__VA_ARGS__))
^
include/mruby.h:100:10: note: macro 'mrb_static_assert_selector' defined here
# define mrb_static_assert_selector(a, b, name, ...) name
^
1 warning generated.
```
Adding `MRB_WORDBOX_NO_FLOAT_TRUNCATE` to the build configuration in 32-bit CPU mode had a double definition.
```console
% cat myconf.rb
MRuby::Build.new do
toolchain "clang"
defines << "MRB_WORDBOX_NO_FLOAT_TRUNCATE"
cc.flags << "-m32"
linker.flags << "-m32"
enable_debug
end
% rake CONFIG=myconf.rb
CPP src/array.c -> build/host/src/array.pi
In file included from /var/tmp/mruby/src/array.c:7:
In file included from /var/tmp/mruby/include/mruby.h:115:
In file included from /var/tmp/mruby/include/mruby/value.h:203:
/var/tmp/mruby/include/mruby/boxing_word.h:11:10: warning:
'MRB_WORDBOX_NO_FLOAT_TRUNCATE' macro redefined [-Wmacro-redefined]
# define MRB_WORDBOX_NO_FLOAT_TRUNCATE
^
<command line>:3:9: note: previous definition is here
#define MRB_WORDBOX_NO_FLOAT_TRUNCATE 1
^
1 warning generated.
...SNIP...
```
The number of registers used is reduced.
Also, previously `R6` and` R7` were used, which exceeded the limit of `new_irep.nregs = 6`.
This could cause the VM stack to overrun.
dearblue