Cannot tell whether a function is supported by the compiler plugin

[Jolanrensen]

Consider the following example:

The into {} overload is unsupported by the compiler plugin, but from a user perspective this is is invisible. They will simply run into runtime exceptions when they run the second example.

We will always have functions like these; that change the data schema but do so with a programmatic approach where a new name depends on some runtime information or data inside the DF.

In these cases, could we have a warning, a color change, a gutter icon or anything similar to let users know when the compiler plugin does and does not adapt the return type?
And is that possible from just the compiler plugin or does that require an IDE plugin?