Re: ${1+"$@"} does not generate multiple words if IFS is empty

[Greg Wooledge]

On Wed, Dec 30, 2015 at 10:02:41AM +0100, Andreas Schwab wrote:
> martijn@inlv.org writes:
> 
> >     The substitution ${1+"$@"} should resolve to "$@" if there is at
> >     least one parameter -- i.e. one word per parameter. This works fine
> >     if IFS contains any character or is unset. If IFS is empty, it
> >     instead resolves to the equivalent of "$*", i.e. a single word
> >     concatenating all the parameters without a separator. IFS should
> >     not influence the behaviour of "$@" under any circumstances.
> 
> http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_05
> 
> "If the value of IFS is null, no field splitting shall be performed."

By itself that doesn't explain it.  But if you scroll up to
http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_05_02
it says:

  @
  Expands to the positional parameters, starting from one. When the
  expansion occurs within double-quotes, and where field splitting (see
  Field Splitting) is performed, each positional parameter shall expand
  as a separate field [...]