[Bug d/103728] New: Allow to run unittests before main()

["pierrick.bouvier at posteo dot net" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103728

            Bug ID: 103728
           Summary: Allow to run unittests before main()
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: d
          Assignee: ibuclaw at gdcproject dot org
          Reporter: pierrick.bouvier at posteo dot net
  Target Milestone: ---

With gdc-12, semantic of unittests will change to match dmd behavior.

So far (<= gdc-11), option -funittest could be used to:
- compile unittest
- automatically run them before main

>From gdc-12, semantic will be:
- compile unittest
- only run them

For users using dub (test), it may sound like the good choice. But for all
others (we use meson), this change is really a burden.

---

>From this post:
https://forum.dlang.org/thread/jrnyklhuqadormjmelae@forum.dlang.org

someone suggested to use this:
version (unittest) extern(C) __gshared string[] rt_options = [
"testmode=run-main" ];

It works well with gdc-12, but it is very cryptic and still hard to add in all
our binaries (we have dozens).

---

Would you consider to add an option -funittest-and-run-main (or similar), to
allow for that thanks to a compiler switch?

Thanks for your hard work on gdc and porting to new front-end.