fix: handle the license with exception case, e.g., llvmlite

[joanise]

Purpose of This Pull Request

Please check the relevant option by placing an "X" inside the brackets:

• Documentation update
• Bug fix
• New feature
• Other (please explain):

Overview of Changes

As described in #137, licensecheck currently hits an unhandled exception when faced with a license with exception, such as is found in llvmlite.

The underlying issue is that not all tokens handled on line 121 of packageinfo.py have a key attribute.

My solution is to guard against this problem with getattr(x, "key", str(x)) which fixes the problem.

Related Issue

If this pull request addresses a specific issue, please mention it using the
format "Fixes #IssueNumber"

Fixes #137

Reviewer Focus

It's a pretty simple patch, so nothing specific.

Additional Notes

I wanted to provide unit testing with my PR, but I did not manage to get the existing suite to run correctly on either my Windows or Linux machine. I've added a minimal data file for testing, however:

licensecheck -r tests/data/issue_137.txt

raises an exception on the current master branch but outputs llvmlite │ APACHE-2.0 WITH LLVM-EXCEPTION;; BSD-2-CLAUSE as expected with this PR.

[nylocx]

Suggested change

	pkg_info.license = ucstr(JOINS.join(getattr(x, "key", str(x)) for x in tokens))
	final_keys = []
	for token in parsed.literals:
	final_keys.extend(sub_symbol.key for sub_symbol in token.decompose())
	pkg_info.license = ucstr(JOINS.join(finals_keys))

Maybe use the decompose function to get the symbols and not fallback to a simple string representation?

[joanise]

Just tested your suggestion, and I'm not sure what the better answer is. With my code, for the test file I provided, I get:

│ ✔          │ llvmlite │ APACHE-2.0 WITH LLVM-EXCEPTION;; BSD-2-CLAUSE │

with your suggested change, instead, I get the warnings 'LLVM-EXCEPTION' License not identified so falling back to UNKNOWN followed by

│ ✔          │ llvmlite │ APACHE-2.0;; LLVM-EXCEPTION;; BSD-2-CLAUSE │

which is not technically correct: llvmlite does not have Apache-2.0 as a license and LLVM-Exception as a license, rather it has "The Apache License v2.0 with LLVM Exceptions" as a license (see https://github.com/numba/llvmlite/blob/main/LICENSE.thirdparty).

Given that, I believe license_expression="BSD-2-Clause AND Apache-2.0 WITH LLVM-exception", (see https://github.com/numba/llvmlite/blob/20226fe41989cffeea322332bb1356c4b1d5a65d/setup.py#L223) should get rendered as my proposed change does.

Maybe there's a cleaner way to accomplish this than my simple casting to a string? I'm open to suggestions.