Add derivedFrom to register maker (rust version only)

[kossnikita]

#158

[burrbull]

If it works correctly, it makes sense to do similar for make_peripheral, make_cluster and make_field.

[kossnikita]

Derive a field does not result in derive an enum, but literally derive a field:

TIMER0:
  CR:
    _modify:
      IDR:
        derivedFrom: RELOAD

Clears enums and add attribute to field.

            <field derivedFrom="RELOAD">
              <name>IDR</name>
              <description>Selects, if Reload Register number is incremented, decremented or not modified</description>
              <bitRange>[27:26]</bitRange>
              <access>read-write</access>
            </field>

As far as I know, no current patch does this. It also doesn't work correctly with svd2rust: it tries to duplicate enumerations in the same module.

[burrbull]

It also doesn't work correctly with svd2rust: it tries to duplicate enumerations in the same module.

Yeah. This is the bug.
Could you open issue in svd2rust repo?

[kossnikita]

rust-embedded/svd2rust#745