Re: AS_VAR_IF and the resulting shell code

[Ralf Wildenhues]

Hello,

* NightStrike wrote on Fri, Oct 16, 2009 at 06:45:57PM CEST:
> xx=yes
> AS_VAR_IF([xx],[yes],[echo equal],[echo not equal])
> results in this:
> 
> xx=yes
> if test "x$xx" = x""yes; then
>   echo equal
> else
>   echo not equal
> fi
> with autoconf 2.63.
> 
> How come the right hand side of the test is x""yes, as in, with two
> double quotes between the x and the yes?  Why isn't it just "xyes", or
> just xyesy?

It's not "xyes", because I think the quoting of the second argument to
AS_VAR_IF was to be the user's responsibility.  (FYI, if you pass a
nonliteral as first argument, then autoconf will expand different code.
xyesy would have been a problem if you pass $foo as second argument.

The two double quotes look a bit ugly in the output, but are not really
problematic.  They are not really needed for the shell, if I remember
correctly, but so that M4 splitting/macro expansion works as expected.

Hope that helps.  Is there an actual bug you've encountered with this
code?

Thanks,
Ralf