Re: [RFA] Emit a warning for ineffective set VAR = EXP command

[<Paul_Koning@Dell.com>]

On May 9, 2012, at 8:28 AM, Tristan Gingold wrote:

> 
> On May 7, 2012, at 9:38 PM, Joel Brobecker wrote:
> 
>>>> This warns about "set variable $j++" presumably -- should the warning be 
>>>> disabled for pre/post increments/decrements?
>>> 
>>> I am not opposed to disable warnings for pre/post inc/dec.
>>> But this usage is dubious (the help explicitly mentions VAR=EXP !)
>>> 
>>> Opinion ?
>> 
>> I think we should avoid the warning for pre/post inc/dec. This
>> type of expression might be a little outside the method proposed
>> in our documentation, but I think it's still a perfectly valid
>> expression that results in an assignment being performed.
> 
> I don't know who should approve this adjustment, but here is the version that deals with pre/post inc/dec.
> Note that it still warns for expressions such as i++ * 2.

If you had it walk through the elts[] list, would it then work for that case?

	paul

> 
> Tested on set-nowarns.exp.
> 
> Tristan.
> 
> 2012-05-09  Tristan Gingold  <gingold@adacore.com>
> 
> 	* printcmd.c (set_command): Add pre/post inc/dec.
> 
> diff --git a/gdb/printcmd.c b/gdb/printcmd.c
> index 79e38f2..fa76296 100644
> --- a/gdb/printcmd.c
> +++ b/gdb/printcmd.c
> @@ -1080,11 +1080,21 @@ set_command (char *exp, int from_tty)
>   struct cleanup *old_chain =
>     make_cleanup (free_current_contents, &expr);
> 
> -  if (expr->nelts >= 1
> -      && expr->elts[0].opcode != BINOP_ASSIGN
> -      && expr->elts[0].opcode != BINOP_ASSIGN_MODIFY
> -      && expr->elts[0].opcode != BINOP_COMMA)
> -    warning (_("Expression is not an assignment (and might have no effect)"));
> +  if (expr->nelts >= 1)
> +    switch (expr->elts[0].opcode)
> +      {
> +      case UNOP_PREINCREMENT:
> +      case UNOP_POSTINCREMENT:
> +      case UNOP_PREDECREMENT:
> +      case UNOP_POSTDECREMENT:
> +      case BINOP_ASSIGN:
> +      case BINOP_ASSIGN_MODIFY:
> +      case BINOP_COMMA:
> +	break;
> +      default:
> +	warning
> +	  (_("Expression is not an assignment (and might have no effect)"));
> +      }
> 
>   evaluate_expression (expr);
>   do_cleanups (old_chain);
>