Re: [Bug report / Bison 1.875] %destructor directive causing segfault during compilation

[Hans Aberg]

At 22:13 -0500 2004/02/07, Jeannot_Langlois wrote:

>%union  /* data types */
>{
>    char chr;        /* character */
>    char* str;       /* string */
>    int val;         /* integer (??NOT USED -- DELETE ME??) */
>}

>/* DESTRUCTORS */
>%destructor { free ($$); } R_MESSAGE
>%destructor { free ($$); } O_PREFIX
>%destructor { free ($$); } R_PREFIX

>I notied that the problems just needs the presence of a single
>%destructor line to trigger a segfault.  As soon as I comment all my
>%destructor lines, the problem vanishes and the C code is produced
>normally without segfaults... but then, if executed, the parser will
>have memory leaks... that's not ok :(.

My suspicion is that the experimental %destructor feature does not look at
the types in order to decide when to apply it. Thus, you might get attempts
to free the other %union fields, that would cause the segmentation fault.

Something for C-programmers to fix. -- I use C++, which comes with builtin
memory releases.

  Hans Aberg