Couldn't cast "time stamp with time zone" to "Date"

[Anish9901]

To Reproduce

• Create a table "t1"
• Add a Date & Time column "dt"
• Try casting "dt" to "Date"
• Notice the following error

Expected behavior

Casting to date from timestamp with time zone should be possible.

[mathemancer]

It's possible, but only if there would be no data loss. Our cast_to_... functions typically don't let users perform casts that would lose precision. If you cast 2025-01-01 00:00:00 +00 to a date, it will work.

We should not solve this problem ad-hoc (i.e., for this specific type or case), but rather as a broader reworking of our casting behavior. These functions are among the first we designed, and we had somewhat different goals for them. They're becoming less and less appropriate as our product goals evolve. We need to:

• Determine precisely what casting behavior we want in Mathesar overall
  • Should we allow loss of precision?
  • Should we use the same behavior in PostgreSQL in all cases?
  • If not, when and why?
  • etc.
• Come up with a plan to implement that behavior in a coherent way so that things feel consistent in the product, rather than piecemeal.