when false doesn't work inside a generic

[timotheecour]

bugs:

• when false doesn't work as I'd expect in case6 (also, it's inconsistent with case1)
• case7 also could be a bug

import std/macros

when defined(case1):
  # works: nothing printed
  proc test1()=
    when false:
      dumpTree:
        discard 1+1

when defined(case2):
  # works: nothing printed
  when false:
    proc test1()=
      dumpTree:
        discard 1+1

when defined(case3):
  # works: nothing printed
  proc test1()=
    when false:
      static: echo "foo"

when defined(case4):
  # works: nothing printed because template not instantiated
  proc test1[]()=
    static: echo "foo"

when defined(case5):
  # works: prints `foo` because not a template
  proc test1()=
    static: echo "foo"

when defined(case6):
  # BUG: prints StmtList(etc) despite `when false`
  proc test1[]()= # likewise with `s/[]/[T]`
    when false:
      dumpTree:
        discard 1+1

when defined(case7):
  # BUG: prints StmtList etc despite generic not instantiated
  proc test1[]()=
    dumpTree:
      discard 1+1

[LemonBoy]

Nah, what happens here is that semGenericStmt expands the dumpTree macros since it has to look at the instantiated AST, the when block is correctly evaluated at the instantiation site.
If you swap the dumpTree: ... block with a static one you'll see that when false works just fine.

[timotheecour]

sorry I fail to see the logic. Why shouldn't when false: foo just disable foo? Anything else seems buggy. Especially case1 vs case6 is inconsistent.
As it stands, when false (or when defined(posix) when we are on windows etc) is not a reliable way to disable a piece of code.