[Bug d/109023] New: d: Add option to include imported modules in the compilation

[ibuclaw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109023

            Bug ID: 109023
           Summary: d: Add option to include imported modules in the
                    compilation
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: d
          Assignee: ibuclaw at gdcproject dot org
          Reporter: ibuclaw at gcc dot gnu.org
  Target Milestone: ---

The reference D compiler has an option `-i` that enables "include imports"
mode, where the compiler will include imported modules in the compilation, as
if they were given on the command line.

Possibly some considerations:

- This option might need to implicitly mean `-fwhole-program', as we don't want
link-time errors to occur as a result of library symbols being in multiple DSOs
(or do we?).

- Would it complicate matters if the same DRT constructor/destructors end up in
multiple DSOs?

- Excluding libphobos and libdruntime modules from being compiled imports would
avoid the main pitfalls I can think of occurring.