BreakpointLocationsRequest without arguments

[nickelpro]

The spec defines that arguments for a BreakpointLocationsRequest are optional, but gives no hint to what meaning such a request would have.

Is the intent for such a request that an adapter should provide all possible breakpoint locations? That's a rather big ask for many adapters.

If so that intent should be documented. If not, then arguments should be a required field for BreakpointLocationsRequest.

[nickelpro]

Worth mentioning that at least one of the listed SDKs (cppdap) does not seem to consider this argument optional at all, and requires at least a line field to be present.

[weinand]

Leaving the arguments property optional was a mistake.

Since making arguments mandatory would be a breaking change, I suggest that we "fix" the problem by documenting the flaw. E.g. something like: "Clients should not omit the arguments property because the DAP specification intentionally does not cover this case. However, if arguments property is missing, debug adapters should return an error."