DDSXTY_ — Type signature fields in built-in topic data shouldn't use unbounded strings

The type_name members of TopicBuiltinTopicData, PublicationBuiltinTopicData, and SubscriptionBuiltinTopicData are bounded at 256 characters. The equivalent_type_name and base_type_name members store sequences of type names, but the strings in those sequences are unbounded. The flexibility to store strings of any length is unnecessary, because no string can appear there that doesn’t also appear in a type_name somewhere, and is therefore of 256 characters or less.

This issue is minor in that it does not impact correctness. However, it does impact clarity to a small extent and can impact the efficiency of some implementations.

Proposed Resolution:

Define a typedef “TypeName”, a string bounded at 256 characters. (See also issue #15969.)

Define a typedef “TypeNameSeq”, an unbounded sequence of TypeName elements.

Change the type of the equivalent_type_name and base_type_name members from StringSeq to TypeNameSeq.

Proposed Revised Text:

TO DO

This issue is obsolete in the face of issue #16561: the resolution of that issue eliminates the type signature concept altogether. Therefore, this issue should be merged with that one.
Disposition: Merged with issue #16561