Way to override/overload D’s runtime assertions to use custom handlers?

[Alexander Nicholi]

Hello,

A project I’m helping develop mixes D code along with C and C++, 
and in the latter two languages we have custom macros that print 
things the way we need to, along with app-specific cleanup tasks 
before halting the program. Because it uses multiple languages, 
two of which have spotty or nonexistent exception support, and 
because we only depend on the D runtime sans libphobos, we have 
opted to avoid the use of exceptions in our codebase. Assertions 
still give us the ability to do contract programming to some 
extent, while C++ and D provide static assertions at compile-time 
to supplement.

With runtime assertions, C and C++ handle things amicably, but 
D’s `assert` builtin seems to fall back to C99’s assert.h 
handlers and there doesn’t seem to be a way around this. Is there 
a way to change this to use our own handlers with the D runtime? 
How does this change without the runtime, e.g. via `-betterC` 
code? If not, is this something that can be implemented in the 
language as a feature request? Our use case is a bit odd but 
still a possibility when using D as a systems-level language like 
this.

Thanks,
Alex