[SizzleUnrlsd]

Summary

Last point of the consolidation: sequence, mapping and class patterns in match.

• Tests first (test: define sequence, mapping and class patterns), implementation follows.
• The HIR represents them (SequencePattern with StarPattern, MappingPattern with a **rest, ClassPattern with keyword sub-patterns); scopes bind their captures as locals.
• The CFG builder, which already lays a match out as an if chain over a hidden subject, desugars them faithfully: a sequence pattern tests the length, exactly or at least when a star is present, applies its sub-patterns to indexed items and binds the star to the middle slice; a mapping pattern tests each key's membership and applies sub-patterns to the values, **rest binding the subject; a class pattern tests isinstance and applies keyword sub-patterns to attributes. Every sub-pattern applies to the expression so built, so patterns nest, guards see the captures and taint flows through them like through any assignment. Positional class patterns need the class's __match_args__ and stay reported per function.
• The existing test that used a sequence pattern as its unsupported example now uses a positional class pattern.

On the sixteen repositories nothing changes. This closes the consolidation list agreed after the roadmap: closure bodies, self state across methods and structural patterns are all in.