[m-rev.] diff: shortcut some unneeded tests

[Julien Fischer]

On Tue, 18 Aug 2020, Zoltan Somogyi wrote:

> This should not need review.
>

> diff --git a/compiler/file_names.m b/compiler/file_names.m
> index b7f83042e..0538cec43 100644
> --- a/compiler/file_names.m
> +++ b/compiler/file_names.m
> @@ -500,11 +499,14 @@ choose_file_name(Globals, _From, Search, OtherExt,
>              % Even if not putting files in a `Mercury' directory,
>              % Java files will have non-empty BaseParentDirs (the package)
>              % which may need to be created.
> -            % XXX Most of the code of make_file_name handles UseSubdirs = yes.
> -            make_file_name(Globals, BaseParentDirs, Search,
> -                BaseNameNoExt, OtherExt, DirComponents, FileName)
> +            % XXX Can we ever target Java while UseSubdirs = no?

No, the Java backend requires the use of mmc --make and that requires
UseSubdirs = yes.  (There is some long obsolete support for using the
Java backend in mmake, but that has not been useful for a very long
time.)

Julien.