Error on method call syntax within a template

[nitely]

Following code doesn't work:

# Module A
proc foo(a: string): string =
  return a

template baz*(a: string): string =
  var b = a.foo()
  b

# Module B
import A

echo baz("hello")
# xxx template/generic instantiation from here
# xxx Error: attempting to call undeclared routine: 'foo'

Works replacing the method call by a regular proc call. Also works as is when using the template within module A. Also works when exporting foo. I can only guess the compiler tries to resolve the method call too late. The method call limitations section of the manual does not mention this specific case.

[jangko]

this is a well known issue, many people already encounter it when using generics. no wonder it also affected templates.
usually, mixin can solve this kind of problem.

template baz*(a: string): string =
  mixin foo
  var b = a.foo()
  b

but it would be nice if the compiler can activate the mixin automatically inside template and generics without specifically typing it (like C++ template).

[nitely]

@jangko except now foo will be picked from caller scope (own, parent, or global) if it's defined there 🤕

# Module B
import A

proc foo(a: string): string =
  return "bye"

echo baz("hello")
# bye

[metagn]

Old issue, but an answer was never given, it's bind foo not mixin foo, which also fixes many of these "private symbol in template" issues

[nitely]

@hlaaftana Using bind instead of mixin throws the same error.

[metagn]

My bad, I was talking out of my ass, it doesn't fix these issues. No one mentioned bind before though so it might help understand what's happening to know that it doesn't work.