Re: New warning in GDB 7.5

Jan Kratochvil
2012-08-20T14:24:58Z

On Sun, 19 Aug 2012 21:10:49 +0200, Mark Kettenis wrote:
> set $tem = (struct Lisp_Symbol *) $ptr
>
> probably won't trigger a full symbol read since "struct Lisp_Symbol"
> is a type and not a function or variable.

It will, because GDB generates symbols for each type. See for example:
process_structure_scope -> new_symbol_full <DW_TAG_structure_type> ->
-> add_symbol_to_list

It should work without any stub 'set' commands, if it does not one should have
a reproducer (one can download Emacs but a minimal reproducer would be
better).

Regards,
Jan

struct s { int i; } v;
gdb -ex r --args ./gdb ./63.o
Reading symbols from /home/jkratoch/redhat/gdb-clean/gdb/63.o...done.
(gdb) maintenance info psymtabs
{ objfile /home/jkratoch/redhat/gdb-clean/gdb/63.o ((struct objfile *) 0x2224c80)
{ psymtab 63.c ((struct partial_symtab *) 0x2218dc0)
readin no
fullname (null)
text addresses 0x0 -- 0x0
psymtabs_addrmap_supported yes
globals (* (struct partial_symbol **) 0x221a780 @ 1)
statics (* (struct partial_symbol **) 0x222fe50 @ 2)
dependencies (none)
}
}
(gdb) maintenance info symtabs
(gdb)
Program received signal SIGINT, Interrupt.
0x00007ffff638dd30 in __poll_nocancel () at ../sysdeps/unix/syscall-template.S:81
81 T_PSEUDO (SYSCALL_SYMBOL, SYSCALL_NAME, SYSCALL_NARGS)
# global symbol
(gdb) p *(* (struct partial_symbol **) 0x221a780 @ 1)[0]
$3 = {ginfo = {name = 0x2218d5a "v", value = {ivalue = 0, block = 0x0, bytes = 0x0, address = 0, chain = 0x0}, language_specific = {mangled_lang = {
demangled_name = 0x0}, cplus_specific = 0x0}, language = language_c, section = 0, obj_section = 0x0}, domain = VAR_DOMAIN, aclass = LOC_STATIC}
# static symbol
(gdb) p *(* (struct partial_symbol **) 0x222fe50 @ 2)[0]
$5 = {ginfo = {name = 0x2218d55 "int", value = {ivalue = 0, block = 0x0, bytes = 0x0, address = 0, chain = 0x0}, language_specific = {mangled_lang = {
demangled_name = 0x0}, cplus_specific = 0x0}, language = language_c, section = 0, obj_section = 0x0}, domain = VAR_DOMAIN, aclass = LOC_TYPEDEF}
# static symbol
(gdb) p *(* (struct partial_symbol **) 0x222fe50 @ 2)[1]
$6 = {ginfo = {name = 0x2218d3e "s", value = {ivalue = 0, block = 0x0, bytes = 0x0, address = 0, chain = 0x0}, language_specific = {mangled_lang = {
demangled_name = 0x0}, cplus_specific = 0x0}, language = language_c, section = 0, obj_section = 0x0}, domain = STRUCT_DOMAIN, aclass = LOC_TYPEDEF}
(gdb) c
Continuing.

(gdb) p (struct s *) 0
$1 = (struct s *) 0x0
(gdb) maintenance info symtabs
{ objfile /home/jkratoch/redhat/gdb-clean/gdb/63.o ((struct objfile *) 0x2224c80)
{ symtab 63.c ((struct symtab *) 0x2219790)
dirname /home/jkratoch/redhat/gdb-clean/gdb
fullname (null)
blockvector ((struct blockvector *) 0x2219770) (primary)
linetable ((struct linetable *) 0x0)
debugformat DWARF 2
}
}