[Bug exp/17106] New: Infinite recursion in in_dynamic_types (e.g. when printing a variable)

["petedeas at fastmail dot fm" <sourceware-bugzilla at sourceware dot org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=17106

            Bug ID: 17106
           Summary: Infinite recursion in in_dynamic_types (e.g. when
                    printing a variable)
           Product: gdb
           Version: 7.7
            Status: NEW
          Severity: normal
          Priority: P2
         Component: exp
          Assignee: unassigned at sourceware dot org
          Reporter: petedeas at fastmail dot fm

Release: 7.7.90.20140701-cvs

OS: Linux petebox 3.15.1-gentoo #1 SMP Sat Jun 21 15:14:16 BST 2014 x86_64
Intel(R) Core(TM) i3 CPU M 370 @ 2.40GHz GenuineIntel GNU/Linux

gcc: 4.8.3 (Gentoo 4.8.3 p1.1, pie-0.5.9) 

(gdb) show configuration
This GDB was configured as follows:
   configure --host=x86_64-unknown-linux-gnu --target=x86_64-unknown-linux-gnu
             --with-auto-load-dir=$debugdir:$datadir/auto-load
             --with-auto-load-safe-path=$debugdir:$datadir/auto-load
             --with-expat
             --with-gdb-datadir=/usr/local/share/gdb (relocatable)
             --with-jit-reader-dir=/usr/local/lib/gdb (relocatable)
             --without-libunwind-ia64
             --with-lzma
             --with-python=/usr
             --without-guile
             --with-separate-debug-dir=/usr/local/lib/debug (relocatable)
             --with-zlib
             --without-babeltrace

How-to-Repeat:

Compile the following (I used g++ -g3 -std=c++98 -Wall demo.cpp -o demo):

// Start of file
#include <iostream>

struct Container;

struct Item {
        Container &m_container;
        int m_n;
        Item(Container &c, int n) : m_container(c), m_n(n) { };
};

struct Container {
        Item m_item;
        Container(int n) : m_item(*this, n) { };
};

int main(int argc, const char *argv[]) {
        Container c(7);
        std::cout << c.m_item.m_n << std::endl;
        return 0;
}
// EOF

Using gdb, attempt to print c after it has been constructed:

Temporary breakpoint 1, main (argc=1, argv=0x7fffffffe148) at demo.cpp:17
17              Container c(7);
(gdb) n
18              std::cout << c.m_item.m_n << std::endl;
(gdb) p c
7
Segmentation fault (core dumped)

For comparison, GDB 7.7.1 does not have this bug, and prints:

$1 = {m_item = {m_container = @0x7fffffffe050, m_n = 7}}

Snippet of backtrace taken during "print c":

...
#42 0x00000000005ca380 in is_dynamic_type (type=0x20f4810) at gdbtypes.c:1647
#43 0x00000000005ca380 in is_dynamic_type (type=0x20f48a0) at gdbtypes.c:1647
#44 0x00000000005ca380 in is_dynamic_type (type=0x20f4810) at gdbtypes.c:1647
#45 0x00000000005ca380 in is_dynamic_type (type=0x20f48a0) at gdbtypes.c:1647
#46 0x00000000005ca380 in is_dynamic_type (type=0x20f4810) at gdbtypes.c:1647
#47 0x00000000005ca380 in is_dynamic_type (type=0x20f48a0) at gdbtypes.c:1647
#48 0x00000000005cdbc1 in resolve_dynamic_type (type=type@entry=0x20f48a0, 
    addr=addr@entry=140737488347200) at gdbtypes.c:1834
#49 0x000000000055ed34 in value_from_contents_and_address
(type=type@entry=0x20f48a0, 
    valaddr=valaddr@entry=0x0, address=address@entry=140737488347200) at
value.c:3412
#50 0x00000000005677b7 in get_value_at (type=0x20f48a0, addr=140737488347200,
lazy=1) at valops.c:920
#51 0x0000000000624e0a in dwarf2_evaluate_loc_desc_full (type=0x20f48a0,
frame=0x1f7fe80, 
    data=0x20a7298 "\221`", size=2, per_cu=0x208d720, byte_offset=0) at
dwarf2loc.c:2329
#52 0x00000000005509e9 in default_read_var_value (var=0x20f67e0,
frame=0x1f7fe80) at findvar.c:435
#53 0x00000000005631b3 in evaluate_subexp_standard
(expect_type=expect_type@entry=0x0, 
    exp=exp@entry=0x217a9c0, pos=0x7fff5c4859dc,
noside=noside@entry=EVAL_NORMAL) at eval.c:771
#54 0x0000000000642a11 in evaluate_subexp_c (expect_type=0x0, exp=0x217a9c0,
pos=0x7fff5c4859dc, 
    noside=EVAL_NORMAL) at c-lang.c:720
#55 0x0000000000561042 in evaluate_subexp (noside=EVAL_NORMAL,
pos=0x7fff5c4859dc, 
    exp=<optimized out>, expect_type=0x0) at eval.c:71
#56 evaluate_expression (exp=<optimized out>) at eval.c:146
#57 0x0000000000577efb in print_command_1 (exp=0x1ebe152 "c", voidprint=1) at
./printcmd.c:977
#58 0x0000000000672ded in execute_command (p=<optimized out>, p@entry=0x1ebe150
"p c", from_tty=1)
    at top.c:461
#59 0x00000000005ba031 in command_handler (command=0x1ebe150 "p c") at
event-top.c:433
#60 0x00000000005ba4dc in command_line_handler (rl=<optimized out>) at
event-top.c:630
#61 0x00000000006be2e0 in rl_callback_read_char () at callback.c:220
#62 0x00000000005ba099 in rl_callback_read_char_wrapper (client_data=<optimized
out>)
    at event-top.c:167
#63 0x00000000005b8d93 in process_event () at event-loop.c:343
#64 0x00000000005b90e7 in gdb_do_one_event () at event-loop.c:407
#65 0x00000000005b9307 in start_event_loop () at event-loop.c:432
#66 0x00000000005b2a63 in captured_command_loop (data=data@entry=0x0) at
main.c:301
#67 0x00000000005afaea in catch_errors (func=func@entry=0x5b2a50
<captured_command_loop>, 
    func_args=func_args@entry=0x0, errstring=errstring@entry=0x780c22 "", 
    mask=mask@entry=RETURN_MASK_ALL) at exceptions.c:524
#68 0x00000000005b3836 in captured_main (data=data@entry=0x7fff5c485da0) at
main.c:1097
#69 0x00000000005afaea in catch_errors (func=func@entry=0x5b2e10
<captured_main>, 
    func_args=func_args@entry=0x7fff5c485da0,
errstring=errstring@entry=0x780c22 "", 
    mask=mask@entry=RETURN_MASK_ALL) at exceptions.c:524
#70 0x00000000005b3d3b in gdb_main (args=args@entry=0x7fff5c485da0) at
main.c:1105
#71 0x000000000045f865 in main (argc=<optimized out>, argv=<optimized out>) at
gdb.c:33

I don't know enough about gdb internals yet to suggest a fix, but I hope this
report is useful.

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