Fix DNP and variant fields being ignored with field case normalization

[DominikPalo]

With "Normalize field name case" / --normalize-field-case enabled, EcadParser.normalize_field_names lowercases the keys of each component's extra fields (e.g. DNP → dnp), but the field names offered in the dialog and passed via --dnp-field / --variant-field keep their original case. generate_bom already accounts for this when looking up shown fields (field.lower()), but two other lookups did not.

skip_component (core/ibom.py)

It looked up config.dnp_field and config.board_variant_field as-is, so with normalization on:

• parts with the DNP field set stayed in the BOM,
• a variant whitelist excluded every part,
• a variant blacklist excluded nothing.

Both names are now lowercased before the lookup when normalize_field_case is set. --variant-field defaults to None rather than '', so the lowercasing is guarded.

FieldsPanel.OnBoardVariantFieldChange (dialog/settings_dialog.py)

It had the same mismatch when collecting the values of the selected variant field, so the whitelist/blacklist choices came up empty with normalization on. The selection is now lowercased too.

Normalization also drops empty values (remap keeps only truthy values). In normalized mode the dialog therefore treats a missing key as empty and offers <empty>, which matches how skip_component treats such components. With normalization off, behavior is unchanged.

Testing

Copy of the KiCad Arduino_Uno template with fields added via pcbnew: DNP=yes on J2, and Variant = A / B / A / (empty) on J1 / J2 / J3 / J4. CLI run with KiCad's Python, mounting holes blacklisted:

Options	master	this PR
--dnp-field DNP	J2 skipped	J2 skipped (unchanged)
--dnp-field DNP --normalize-field-case	J1, J2, J3, J4 in BOM	J2 skipped
--variant-field Variant --variants-whitelist A --normalize-field-case	empty BOM	J1, J3
--variant-field Variant --variants-blacklist B --normalize-field-case	nothing excluded	J2 excluded
--variant-field Variant --variants-whitelist "A,<empty>" --dnp-field DNP	J1, J3, J4	unchanged

Dialog: I instantiated the real SettingsDialog with KiCad's wxPython, loaded the board as extra data, selected Variant as the variant field and read the whitelist items:

	master	this PR
normalize off	<empty>, A, B	<empty>, A, B
normalize on	(empty list)	<empty>, A, B

Not addressed here: when the dialog opens, set_extra_data_path parses the extra data before transfer_to_dialog restores a saved "normalize case" setting. That is a separate ordering issue.

🤖 Generated with Claude Code

[qu1ck]

Don't invent empty value if field is not set.