Hello Ian, Erik, all,
This seems to be declared both in interface.ccl as well as in this (and another) source file.
Yup. I see it. Erik actually beat you to it, Ian. I do not know why this ever compiled. The line in question was last changed on August 8th. It declares (so Erik tells me, I am still compiling) a variable that is never used.
The simple fix is to remove the unused declaration.
I'll try and hunt down why this started to fail now.
Yours, Roland