There's some strong (i hope a decent number of people here would say "winning") counterarguments, scala macros and implicits are incredibly useful. (i see lots of complaints about C++ template error messages, but i haven't been doing C++ so can't comment informedly)
I think a better rule is if the tooling can't look at the source, intermediate compiler stages/ AST and bytecode/binary and tell you unambiguously where something came from, then you can characterize it as a "last resort"
And there's the counterargument that for statically typed languages with good type systems (scala, haskell, ocaml, F#), there's REPL prototyping/testing and code generated from template haskell or camlp4 has to type check, so you have multiple safety mechanisms
I think a better rule is if the tooling can't look at the source, intermediate compiler stages/ AST and bytecode/binary and tell you unambiguously where something came from, then you can characterize it as a "last resort"
And there's the counterargument that for statically typed languages with good type systems (scala, haskell, ocaml, F#), there's REPL prototyping/testing and code generated from template haskell or camlp4 has to type check, so you have multiple safety mechanisms