"extern functions have no body" innaccurate

[xNxExOx]

zig/lib/std/zig/Ast.zig

Line 456 in d07360f

return w.writeAll("extern functions have no body");

I would recommend:

extern functions should have no body

or

extern functions must have no body

or

extern functions can not have a body

To be explicit about the fact that the body is there, but should not be.