[Rd] Viewing R objects in gdb

[Duncan Murdoch]

I'm trying to track down a bug in some experimental code, where an 
object's attribute is getting messed up.  This means I'd like to examine 
R objects while within gdb.

One of the things I'd like to do is to examine the names of all the 
attributes.  This is exactly what an example in the R Extensions manual 
section 4.11.2 "Inspecting R objects when debugging" does, but the code 
there doesn't work, presumably because the R internals have changed 
since it was written.

Specifically, I get

(gdb) p $a->u.listsxp.tagval->u.symsxp.pname->u.vecsxp.type.c
Error: There is no member named vecsxp.

where $a was set to be the attrib member of an SEXP.

Could someone let me know what needs to be fixed for this to work?  I 
imagine it's a typecast, but I haven't been able to put it together.

(An example using R_PV to print the attributes of an SEXP would also be 
welcome, but I can probably figure that one out once I get this...)

Duncan Murdoch