Dot-like operators preview feature does not parse number literals on right hand side

[kaushalmodi]

There's a regression on Nim devel that's breaking a previously working example.

Example

iterator `.++`[T](a: T, b: T): T =
  ## Increment each output by 2
  var res: T = a
  while res <= b:
    yield res
    inc res
    inc res

for i in 0 .++ 8:
  echo i

Current Output

/tmp/babel-9Of7gI/nim_src_8GtwME.nim(12, 16) Error: identifier expected, but got '8'

Expected Output

0
2
4
6
8

Possible Solution

• If I change the iterator identifier to something like `..` or `==`, the same example works.

Additional Information

This example works with Nim 1.6.6. See https://play.nim-lang.org/#ix=3Ybx.

$ nim -v
Nim Compiler Version 1.7.1 [Linux: amd64]
Compiled at 2022-05-19
Copyright (c) 2006-2022 by Andreas Rumpf

git hash: 63cca93ea9bcab3c1fea39ff3789fd3a656d2db2
active boot switches: -d:release

[metagn]

Simpler example:

template `.++`(a, b): untyped = a + b

discard (1 .++ 2)

The reason this is broken in devel is because dot-like operators are enabled by default. The same error is given in 1.6 if you do -d:nimPreviewDotLikeOps. For some reason dot-like operators are designed to only allow an identifier afterward. Don't know the reason for this limitation so I don't know how far this can be relaxed.

[metagn]

Dot-like operators are now deprecated and no longer enabled by default, so this works now, but the issue is probably still there with dot-like operators, so we can keep this open until dot-like operators are gone. (as noted above, this seems like an arbitrary limitation and shouldn't be hard to fix)