Short: filter() clobbers a svalue
Date: Mon, 2 Oct 2000 17:44:05 -0500
From: Casey Zacek <cz@800hosting.com>
Type: Bug
State: Done - fixed in 3.2.9-dev.235


Well, from reading the changelogs and such, I thought this one might
have been fixed in dev.233, but I guess not:

create() {
    int *i = ({ 1 });
    filter( ({ 2, 3, 4 }), "f", &(i[0]) );
}

void f( int x, int ref ) {
    printf( "ref: %O\n", ref );
}

yields:

ref: 1
ref: !ERROR: GARBAGE SVALUE (816)!
ref: !ERROR: GARBAGE SVALUE (816)!

Analysis:
Protected lvalues don't have a refcount, so on the first return from the
callback, the lvalue was freed even though it was still needed.

A real solution would require a major rewrite of the lvalue system, so for
now protected lvalues are verboten for multiple callbacks.