event_match push rule condition behavior for non-string values is unspecified

[jplatte]

Link to problem area: https://matrix.org/docs/spec/client_server/r0.6.1#conditions

Issue

The event_match condition has a key parameter that allows choosing any part of an event to be matched against a glob pattern. Glob matches operate on strings, but the JSON value at key might be an array, a number, a boolean or null too (an object is impossible if matching is implemented the same way as in Synapse, i.e. by first flattening the event JSON). The spec should clarify what to do in this case. The two possibilities I see:

• Ignore arrays; stringify numbers, booleans and nulls
• Ignore anything that's not a string

See also:

• Ruma issue about this: Decide what to do about non-strings in push rule matching ruma/ruma#451
• Other issues about event_match: spec is wrong for event_match.pattern push rule condition #2637, Glob flavor used for event_match is not clear #3075