0.5: `1.im` gives error `ERROR: syntax: invalid numeric constant "1.i"`

[dlfivefifty]

Not sure if this is intentional or not, but the syntax 1.im now gives an error

ERROR: syntax: invalid numeric constant "1.i"

If this is intentional, I would have expected a more explanatory error message.

[yuyichao]

This is intentional. #16339

[JeffBezanson]

Maybe it would be better to say "numeric literals ending in . cannot be implicitly multiplied" or similar?