ERROR: syntax: invalid named tuple element misleading message

[goretkin]

The following code produces the following syntax error.

julia> d = 4
4

julia> (
           a=2,
           b=3,
           c = (d=d)
           )
ERROR: syntax: invalid named tuple element "2"

The fix is to add a trailing , (comma) to the named tuple of one element, which is not quite what the error message says.

julia> (
           a=2,
           b=3,
           c = (d=d,)
           )
(a = 2, b = 3, c = (d = 4,))

julia> versioninfo()
Julia Version 1.0.2
Commit d789231e99 (2018-11-08 20:11 UTC)
Platform Info:
  OS: macOS (x86_64-apple-darwin14.5.0)
  CPU: Intel(R) Core(TM) i7-4960HQ CPU @ 2.60GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-6.0.0 (ORCJIT, haswell)

(I ran into this when porting code away from using NamedTuples.jlon juia v0.6)

[JeffBezanson]

Thanks for catching this. There is indeed a glaring bug here, but after fixing it there won't be an error, since (d=d) is a valid expression. For example f(a=(b=c)) assigns b = c, then passes the value of c as the a argument to f. I guess we can decide separately whether to change anything about that.

[goretkin]

I didn't catch that, but of course you're right. I had some non-syntax bugs in my code because @nt(a=3) produced a tuple, but (a=3) on v0.7 did not.

I think it's perfectly okay if there is no error for my original code. (3) doesn't produce a tuple, and neither does (a=3).