There are a few condition macros expanding to a list of other conditions:
The user can also define condition macros using the hook predicate below.
Body) is substituted for the original condition. The expansion is done at the time the breakpoint is added.
Note that Body can be composite, but it cannot be of form
-Actions. This means that the whole Body
will be interpreted as being in either the test or the action part,
depending on the context.
The built-in breakpoint conditions cannot be redefined using this predicate. See mpg-ref-breakpoint_expansion.