[m-rev.] for review: always-in-cur-dir group of extensions

[Julien Fischer]

On Wed, 9 Aug 2023, Zoltan Somogyi wrote:

> Group all "always in current dir" extensions together.
> 
> compiler/file_names.m:
>     Replace several groups of extensions that stood for semantically
>     different groups of extensions by one group, the "always in the
>     current directory" group. The enum type of the new type representing
>     the now larger group consists of the enum values from the types
>     representing the old, smaller groups. The old boundaries are thus
>     no longer expressed in types, but still remain in the naming schemes
>     of the enum values.
>
>     Once we have done the same for the six other groups of extensions,
>     with each group having its own pattern of where its extensions are put
>     under which circumstances, we can replace code that does multiple
>     modulename+extension to filename translations with code that does
>     one modulename+extension to DIRECTORY PATH translation, and then
>     constructs multiple filenames from that, repeating just the
>     "extension enum to extension string" part of the old translation
>     for each operand. We can do this because unlike the old extension
>     categories, the new ones will make clear which groups of extensions
>     are guarantee to map to the same directory path, and which have
>     no such guarantee.

That's fine.

Julien.