GDB 7.3.1 not working with GCC 4.6.2 on OS X 10.7.2

[Hans Aberg]

[I am not on this list, so please cc me.]

GDB 7.3.1 on OS X 10.7.2 is not working. The link below suggests that in late 
October, it worked.

Debugging some code as normal user, I get the first output below: first some 
complaints from BFD, and then a statement "Unable to find Mach task port" 
suggesting the problem has to do woth it not being codesigned. However, 
attempts with codesigning it did not help, the /usr/bin/gdb 6.3.50-20050815 
(Apple version gdb-1708) that comes with Xcode 4.2 is not codesigned.

When debugging as root (sudo), I get the second output below. The difference is 
that the Mach task port error has been replaced by
  Cannot insert breakpoint 1.
  Error accessing memory address 0x10000495b: Input/output error.
So it seems broken anyway. 

The code was compiled using Apple clang version 3.0 (tags/Apple/clang-211.12). 
However, the errors are the same when compiled with gcc 4.6.2; the output is 
the same as normal user, and as root the same type of memory access error is 
output twice.

Attempting to use the gdb 6.3.50 mentioned above gives the fourth output below, 
"Dwarf Error: Cannot find type of die", which I think it means it is too old to 
handle the debugging info of gcc 4.6.2.

Hans


http://groups.google.com/group/golang-nuts/browse_thread/thread/b2b9719f057c7673

-----
$ gdb test
GNU gdb (GDB) 7.3.1
...
This GDB was configured as "x86_64-apple-darwin11.2.0".
...
BFD: unable to read unknown load command 0x24
BFD: unable to read unknown load command 0x26
BFD: unable to read unknown load command 0x24
BFD: unable to read unknown load command 0x26
Reading symbols from <path>/test...done.
(gdb) break test.cc:53
Breakpoint 1 at 0x10000495b: file test.cc, line 53.
(gdb) run
Starting program: <path>/test 
Unable to find Mach task port for process-id 56470: (os/kern) failure (0x5).
 (please check gdb is codesigned - see taskgated(8))
(gdb) 
----
# gdb test
GNU gdb (GDB) 7.3.1
...
This GDB was configured as "x86_64-apple-darwin11.2.0".
...
BFD: unable to read unknown load command 0x24
BFD: unable to read unknown load command 0x26
BFD: unable to read unknown load command 0x24
BFD: unable to read unknown load command 0x26
Reading symbols from <path>/test...done.
(gdb) break test.cc:53
Breakpoint 1 at 0x10000495b: file test.cc, line 53.
(gdb) run
Starting program: <path>/test 
BFD: unable to read unknown load command 0x24
BFD: unable to read unknown load command 0x26
Error in re-setting breakpoint 1: Cannot access memory at address 0x100004420
Warning:
Cannot insert breakpoint 1.
Error accessing memory address 0x10000495b: Input/output error.

(gdb) 
----
# gdb test
GNU gdb (GDB) 7.3.1
...
This GDB was configured as "x86_64-apple-darwin11.2.0".
...
BFD: unable to read unknown load command 0x24
BFD: unable to read unknown load command 0x26
BFD: unable to read unknown load command 0x24
BFD: unable to read unknown load command 0x26
Reading symbols from <path>/test...done.
(gdb) break test.cc:53 
Breakpoint 1 at 0x1000027d9: file test.cc, line 53. (2 locations)
(gdb) run
Starting program: <path>/test 
BFD: unable to read unknown load command 0x24
BFD: unable to read unknown load command 0x26
Error in re-setting breakpoint 1: Cannot access memory at address 0x100002580
Warning:
Cannot insert breakpoint 1.
Error accessing memory address 0x1000027d9: Input/output error.
Cannot insert breakpoint 1.
Error accessing memory address 0x10000304d: Input/output error.

(gdb) 
----
$ /usr/bin/gdb test
GNU gdb 6.3.50-20050815 (Apple version gdb-1708) (Thu Nov  3 21:59:02 UTC 2011)
...
This GDB was configured as "x86_64-apple-darwin"...Reading symbols for shared 
libraries ..... done

(gdb) break test.cc:53
Die: DW_TAG_unspecified_type (abbrev = 15, offset = 1219)
        has children: FALSE
        attributes:
                DW_AT_name (DW_FORM_string) string: "decltype(nullptr)"
Dwarf Error: Cannot find type of die [in module <path>/test]
(gdb) 
----