Regression involving templates instantiated within generics

[MasonMcGill]

The following code compiles with compiler versions before commit 34b4e9f, and fails with later versions:

import macros

template forStatic(index: expr, slice: Slice[int], predicate: stmt):
                   stmt {.immediate.} =
  const a = slice.a
  const b = slice.b
  when a <= b:
    template iteration(i: int) =
      block:
        const index = i
        predicate
    template iterateStartingFrom(i: int): stmt =
      when i <= b:
        iteration i
        iterateStartingFrom i + 1
    iterateStartingFrom a

proc concreteProc(x: int) =
  forStatic i, 0..3:
    echo i

proc genericProc(x: any) =
  forStatic i, 0..3:
    echo i

concreteProc(7) # This works
genericProc(7)  # This doesn't compile

The error message:

test.nim(28, 11) Info: template/generic instantiation from here
test.nim(17, 4) Info: template/generic instantiation from here
test.nim(15, 8) Info: template/generic instantiation from here
test.nim(11, 22) Error: cannot evaluate at compile time: x

However, variations on this code can cause

• Symbols that are not integers being converted to type int.
• Internal errors in genRecordField.

Use-case/significance: All of my current projects use some version of the forStatic snippet for compile-time iteration. It's the most straightforward approach to manipulating elements of generic arrays/tuples without actually generating loops (which may be too expensive in some situations, e.g. transforming tensor indices).