Thanks Joren.

Is this the change that causes mypy unreachable warnings in code like this

match array.dtype:
   case np.int:
      ...
   case np.float:
     ...

?

Is this the change that causes mypy unreachable warnings in code like this

match array.dtype:
   case np.int:
      ...
   case np.float:
     ...

?

np.float and np.int do not exist, so that might be why

Is this the change that causes mypy unreachable warnings in code like this

match array.dtype:
   case np.int:
      ...
   case np.float:
     ...

?

In case you meant np.int_ and np.float64, then it could be related to one of these mypy issues:

• Maybe a problem with reachability of Match cases python/mypy#12778
• False unreachable warning on match statement python/mypy#14485
• Type inference issue with match expression in generic functions python/mypy#15930
• "Statement is unreachable" when doing match on type objects python/mypy#18524
• Matching on boolean expressions does not narrow based on the content of the boolean expression python/mypy#18833
• Wrong types when pattern matching int with http.HTTPStatus python/mypy#18866

Sorry, the actual code is:

  match data.dtype:
         case np.uint16:
                    data = data.astype(np.int32)
         case np.uint32 | np.uint64:
                    data = data.astype(np.int64)

This works in mypy with numpy <2.2, but breaks in numpy 2.3.

But the issue is caused by array.dtype no longer being Any -- sorry.