Re: Infinite recursions in math evaluation

[Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx>]

On May 13, 11:37pm, Mikael Magnusson wrote:
}
} [...]  Aha, actually a=a; $(( a )) crashes in the same way. (On
} a machine with a presumably less optimized/buggy compile, it does
} print "zsh: math recursion limit exceeded" instead of crashing). Is it
} simply a user error? I wouldn't expect either of these expressions to
} recursively look up values of the parameter until it encountered a
} number, but this is indeed what happens:
} % a=b; b=c; c=d; d=e; e=f; f=5; echo $(( a ))
} 5
} bash does the same...
} 
} I scanned quickly through the "Arithmetic Evaluation" section and
} found nothing suggesting that this should happen.

It's implicit in this:

    Named parameters and subscripted arrays can be referenced by name
    within an arithmetic expression without using the parameter expansion
    syntax.  For example,

        ((val2 = val1 * 2))

    assigns twice the value of $val1 to the parameter named val2.

"The value of $val1" in an arithmetic context is the result of doing
arithmetic evaluation on whatever is stored in the parameter.  If
that's the name of another (or even the same) parameter, then ...