[patch[ Improve the error messages of tvariable command

[Pedro Alves]

On 02/13/2013 04:58 PM, Abid, Hafiz wrote:
> On 13/02/13 16:47:38, Pedro Alves wrote:
>> I somewhat remember investigating this, and writing a longer
>> rationale for the change -- the gist of it being not
>> handling tsv name as expressions.   Can you dig it out from
>> the internal archives and repost including that info?  It'd
>> be good for posterity.
>>
>> -- 
>> Pedro Alves
>>
>>
> 
> Here is what I found. Is it what you were expecting?
> 
> -- 
> 
> Here's a fix for issue #8161, which is about the "tvariable" returning
> errors on invalid and tsv names.  E.g.,
> 
>  Temporary breakpoint 1, main () at a.cc:2
>  2           int x = 1;
>  (gdb) tvar x
>  Syntax must be $NAME [ = EXPR ]
>  (gdb) tvar y
>  No symbol "y" in current context.
> 
> The problem is the use of parse_expression to parse the tvariable's
> name.  We could merely always catch errors thrown from within
> parse_expression, and issue a "usage" error, but it wouldn't cover
> all cases correctly.  E.g.,
> 
>  (gdb) tvar x = nonexistingvariable
> 
> is an invalid expression, not invalid syntax.
> 
> I also noticed that
> 
>  (gdb) tvar x = 1 = 1
> 
> would be incorrectly accepted.
> 
> Given that the comand is documented to only take an expression
> on the right side of the '=', it seems that whatever is on
> the left side of the '=' should not be treated as an expression, but
> literaly as "$NAME".  That's what the patch does.

Ah, that's it.  Thanks for digging it out.

> MI now shares the same name validations as the CLI variant.

-- 
Pedro Alves