Passing anonymous proc params to templates may fail

[etan-k]

Passing an anonymous proc to a template may fail under Nim 1.2.12.

Example

type
  X* = ref object
    bar: proc (p: proc(v: openArray[byte]))

template foo(x: X, p: proc(v: openArray[byte])) =
  x.bar(p)

X().foo(proc(v: openArray[byte]) = discard @v)

Current Output

Error: internal error: expr: param not init v_4602025

Expected Output

Compilation should succeed

Possible Solution

• Defining a named proc and passing the proc by name works fine.
• Using a proc instead of a template works fine.

Additional Information

• This bug is only present on the 1.2 branch of Nim.
• On 1.4, the bug has been fixed as of 341be0b.
• Backporting said commit on top of 1.2 fixes the bug, but this may introduce breaking changes as the AST representation of procs is modified.

$ nim -v
Nim Compiler Version 1.2.13 [MacOSX: amd64]
Compiled at 2021-08-05
Copyright (c) 2006-2020 by Andreas Rumpf

git hash: 76560576d2dd8ab1876fd4f81029d55467088354
active boot switches: -d:release

[metagn]

As mentioned in the issue, works in 1.4 and now