license_expression for 'ASL 2.0' is unknown

[qduanmu]

Description

Declared license in rpm spec is License: ASL 2.0, and scancode failed to get the correct license expression.

>>> from packagedcode.models import compute_normalized_license
>>> compute_normalized_license('ASL 2.0')
'unknown'

After adding a license rule with 'ASL 2.0' as rule text for 'apache-2.0', reindexed icenses, the license expression could be recognized correctly.

>>> compute_normalized_license('ASL 2.0')
'apache-2.0'

Same issue for 'ASL 1.1', 'ASL 1.0'.

System configuration

For bug reports, it really helps us to know:

• What OS are you running on? Linux (f29)
• What version of scancode-toolkit was used to generate the scan file? ScanCode version 3.1.1
• What installation method was used to install/run scancode? (pip/source download/other)? pip

[pombredanne]

@qduanmu good catch.
There are two different ways we could consider to fix this:

1. as you suggested we could add rules, with the risk that some of these are are very short and lead to some false positive when found in another context (e.g. not in an RPM metadata)
2. alternatively, we could add a new type of license detection "matchers" that would be specific to each package type and could be as simple as a mapping for RPMs, mapping each known license declarations used in RPMs to an actual license expression.. (this could be smart and be distro-specific too)