[m-rev.] diff: Delete unused imports.

[Zoltan Somogyi]

On Wed, 30 Mar 2022 16:17:07 +1100, Peter Wang <novalazy at gmail.com> wrote:
> > I don't agree. I have been saying that mmc's correct behavior for the version
> > of call_gen.m that includes an implementation section import of vartypes.m,
> > is NOT to generate an unused import warning for that import.
> > 
> 
> Then call_gen.m must be using an entity exported by vartypes.m, correct?
> Can you explain to me what constitutes the "use" in call_gen.m?

Deciding what the target language type should be of the target language
variable that holds the value of the Mercury variable whose type is "vartypes",
which is a type that is exported by vartypes.m. For the LLDS backend,
the only thing it needs to know whether to reserve two words for it instead
of one, as for a 64 bit double on a 32 bit platform, but when generating
Java or C#, the code generator needs to know the specific target language type.

Zoltan.