Command calls don't work with a single named arg

[dawkot]

Example

proc myProc(x = 0) = discard

myProc x=1 # error: undeclared identifier: 'x'

Additional Information

• 1.2.4, 14d16c2

[metagn]

It only works when the first argument is unnamed.

proc foo(a, b: int) = echo a + b

foo 4, b = 5 # 9

[timotheecour]

IIUC it's because of precedence rules, look at

import macros
macro deb(a): untyped =
  echo a.treeRepr
  echo a.repr
deb:
  myProc x=1

StmtList
  Asgn
    Command
      Ident "myProc"
      Ident "x"
    IntLit 1

myProc x = 1

EDIT: looks like a common gotcha, see this recent post: https://forum.nim-lang.org/t/8037

the question is: how can we improve things here without introducing parser ambiguties?

on possible rule is:

myProc x = 1 # still parsed as (myProc x) = 1
myProc x = 1, expr # previously rejected by parser, now accepted as myProc(x = 1, expr)

which does not sound ambiguous