Re: [PATCH] Catch errors in value_get_print_value

[Nick Roberts <nickrob@snap.net.nz>]

 > > Currently when common_val_print throws an error from install_new_value it gets
 > > caught in mi_execute_command and prints an MI error (^error,...)  without
 > > cleaning up.  This patch catches the error in value_get_print_value so that GDB
 > > can proceed normally.  It could be adapted to output something like
 > > "<error_reading_variable>" but I think the empty string works better.
 > 
 > Could you explain why?  I would be confused to see an empty value in
 > my locals window.  That's separate from this bug though.

It's much quieter than a window full of error/warning messages.  If there's no
value available, the frontend doesn't show one.  That seems logical to me but
perhaps only because I'm used to it.


 > > !   TRY_CATCH (except, RETURN_MASK_ERROR)
 > > !     {
 > > !       common_val_print (value, stb, format_code[(int) format], 1, 0, 0);
 > > !     }
 > > ! 
 >
 > val_print, called by common_val_print, already has code to catch this
 > error and prettyprint it.  

Yes but I think the error is in value_contents_all.  It's the only way that I can
catch it in varobj.c.

 ...
 > So I checked this in instead.  Let me know if it doesn't work for you.
 >
 > -- 
 > Daniel Jacobowitz
 > CodeSourcery
 > 
 > 2007-02-08  Daniel Jacobowitz  <dan@codesourcery.com>
 > 
 > 	* varobj.c (install_new_value): Only call value_get_print_value
 > 	if changeable.
 > 
 > Index: varobj.c
 > ===================================================================
 > RCS file: /cvs/src/src/gdb/varobj.c,v
 > retrieving revision 1.82
 > diff -u -p -r1.82 varobj.c
 > --- varobj.c	24 Jan 2007 19:54:13 -0000	1.82
 > +++ varobj.c	8 Feb 2007 17:38:36 -0000
 > @@ -953,7 +953,7 @@ install_new_value (struct varobj *var, s
 >    /* If the type is changeable, compare the old and the new values.
 >       If this is the initial assignment, we don't have any old value
 >       to compare with.  */
 > -  if (initial)
 > +  if (initial && changeable)
 >      var->print_value = value_get_print_value (value, var->format);
 >    else if (changeable)
 >      {

Thanks.  This is clearly a better patch as it's much simpler.  Thinking more
generally, I wonder if there are other cases where value_contents_all should
catch this error?

-- 
Nick                                           http://www.inet.net.nz/~nickrob