When building `WITH_PYTHON`, where a global list of modules is maintained, deleting a module also erases the entry in said global list. This can lead to memory corruption if the global list is destructed before the module.
Using `on_shutdown()` instead means the module destructor is explicitly called before the global list can be destructed, preventing the issue.
Also add a comment to `Pass::~Pass()` to suggest the same for future passes that might try to use that (and see this commit in the blame if they need a reason why).
Use `Design::selected_modules()` directly, popping at the end instead of copying the selection.
Also default to a complete selection so that boxes work as before.
Simplify to using `RTLIL::SELECT_WHOLE_CMDERR` instead of doing it manually.
Also add tests for importing selections with boxes.
This patch should support things like
`define foo(a, b = 3, c) a+b+c
`foo(1, ,2)
which will evaluate to 1+3+2. It also spots mistakes like
`foo(1)
(the 3rd argument doesn't have a default value, so a call site is
required to set it).
Most of the patch is a simple parser for the format in preproc.cc, but
I've also taken the opportunity to wrap up the "name -> definition"
map in a type, rather than use multiple std::map's.
Since this type needs to be visible to code that touches defines, I've
pulled it (and the frontend_verilog_preproc declaration) out into a
new file at frontends/verilog/preproc.h and included that where
necessary.
Finally, the patch adds a few tests in tests/various to check that we
are parsing everything correctly.
o Not all derived methods were marked 'override', but it is a great
feature of C++11 that we should make use of.
o While at it: touched header files got a -*- c++ -*- for emacs to
provide support for that language.
o use YS_OVERRIDE for all override keywords (though we should probably
use the plain keyword going forward now that C++11 is established)
