Re: [RFA] Fix frame argument printing when using auto language mode

[Xavier Roirand <roirand@adacore.com>]

Le 2/20/18 à 4:15 PM, Yao Qi a écrit :
> On Mon, Feb 19, 2018 at 12:52 PM, Xavier Roirand <roirand@adacore.com> wrote:
>>
>> The problem is that GDB prints the S parameter in the pck.call_me Ada
>> function using the current language, so the C one, because the program
>> is stopped in a C function, whereas it should use the pck.call_me frame
>> one. This behavior is ok when user manually changes the language but it's
>> not the right one when language is auto.
> 
> Agreed, GDB should use per-frame language instead of global current
> language.  However, instead of switching global variable current_language,
> why don't we pass the per-frame language down to la_val_print?  In
> ada-valprint.c:ada_val_print,
> 
>        ada_val_print_1 (type, embedded_offset, address,
>         stream, recurse, val, options,
>         current_language);
>         ^^^^^^^^^^^^^^^^^
> 
> why don't pass language for ada here?
> 

Hello Yao,

It was my first idea, but it would imply a consequent amount of work 
because when ada_val_print_1 is called, the stack is the following one:

#0  ada_val_print_1
#1  ada_val_print
#2  val_print (got the language of the frame arg)

So if we want to pass the per-frame language down to ada_val_print_1 
then in the generic val_print function, we have to change:

       language->la_val_print (type, embedded_offset, address,
                               stream, recurse, val,
                               &local_opts);
to something like:

       language->la_val_print (type, embedded_offset, address,
                               stream, recurse, val,
                               &local_opts, language);
                                            ^^^^^^^^

Fix me if I'm wrong but it means that <language>_val_print functions for 
all the supported GDB languages have to be modified in order to support 
the language parameter.

Regards.