gdb/PROBLEMS

			Known problems in GDB 6.2

		See also: http://www.gnu.org/software/gdb/bugs/


*** Build problems

build/1411: build fails on hpux 10.20 and hpux 11.00 with CMA threads

GDB does not build on HP/UX 10.20 or HP/UX 11.00 if the CMA
thread package is installed.  The compile error is:

  ../../gdb/hpux-thread.c:222: variable-size type declared outside of any function

This happens only if the CMA thread package is installed.

As a workaround, you can disable support for CMA threads
by editing the file gdb/configure.  Find the line:

  if test -f /usr/include/dce/cma_config.h ; then

And replace it with:

  if false ; then

build/1458: compile failed on hpux11

GDB has build problems on HP/UX 11 with some versions of the HP
Ansi C compiler.  (GCC works fine).

The problem happens when compiling intl/bindtextdom.c.
The error is:

  cc: "gettextP.h", line 50: error 1000: Unexpected symbol: "SWAP".
  cc: panic 2017: Cannot recover from earlier errors, terminating.
  *** Error exit code 1

This is a problem with the 'inline' keyword in gettextP.h.
The workaround is to disable 'inline' before building gdb:

  export ac_cv_c_inline=no

This problem happens only with some versions of the HP Ansi C compiler.
Versions A.11.01.25171.GP and B.11.11.28706.GP have both been observed
to work; version B.11.11.04 gets the build error and needs the
workaround.

This problem might also happen with other C compilers.

*** Misc

gdb/1560: Control-C does not always interrupt GDB.

When GDB is busy processing a command which takes a long time to
complete, hitting Control-C does not have the expected effect.
The command execution is not aborted, and the "QUIT" message confirming
the abortion is displayed only after the command has been completed.

*** C++ support

gdb/931: GDB could be more generous when reading types C++ templates on input

When the user types a template, GDB frequently requires the type to be
typed in a certain way (e.g. "const char*" as opposed to "const char *"
or "char const *" or "char const*").

gdb/1512: no canonical way to output names of C++ types

We currently don't have any canonical way to output names of C++ types.
E.g. "const char *" versus "char const *"; more subtleties arise when
dealing with templates.

gdb/1516: [regression] local classes, gcc 2.95.3, dwarf-2

With gcc 2.95.3 and the dwarf-2 debugging format, classes which are
defined locally to a function include the demangled name of the function
as part of their name.  For example, if a function "foobar" contains a
local class definition "Local", gdb will say that the name of the class
type is "foobar__Fi.0:Local".

This applies only to classes where the class type is defined inside a
function, not to variables defined with types that are defined somewhere
outside any function (which most types are).

gdb/1588: names of c++ nested types in casts must be enclosed in quotes

You must type
  (gdb) print ('Foo::Bar') x
or
  (gdb) print ('Foo::Bar' *) y
instead of
  (gdb) print (Foo::Bar) x
or
  (gdb) print (Foo::Bar *) y
respectively.

gdb/1091: Constructor breakpoints ignored
gdb/1193: g++ 3.3 creates multiple constructors: gdb 5.3 can't set breakpoints

When gcc 3.x compiles a C++ constructor or C++ destructor, it generates
2 or 3 different versions of the object code.  These versions have
unique mangled names (they have to, in order for linking to work), but
they have identical source code names, which leads to a great deal of
confusion.  Specifically, if you set a breakpoint in a constructor or a
destructor, gdb will put a breakpoint in one of the versions, but your
program may execute the other version.  This makes it impossible to set
breakpoints reliably in constructors or destructors.

gcc 3.x generates these multiple object code functions in order to
implement virtual base classes.  gcc 2.x generated just one object code
function with a hidden parameter, but gcc 3.x conforms to a multi-vendor
ABI for C++ which requires multiple object code functions.

*** Signal handlers

On many systems an attempt to single-step a system-call instruction
results in two or more instructions being executed (the system-call,
and one or more instructions following).

When attempting to single-step through a signal trampoline, this
problem may result the program unintentionally running to completion,
or re-execute the faulting instruction, or even corrupting the program
counter.

Ref: PR breakpoints/1702.

*** Stack backtraces

GDB's core code base has been updated to use a new backtrace
mechanism.  This mechanism makes it possible to support new features
such DWARF 2 Call Frame Information (which in turn makes possible
backtraces through optimized code).

Since this code is new, it is known to still have a few problems:

gdb/1505: [regression] gdb prints a bad backtrace for a thread

When backtracing a thread, gdb does not stop when it reaches the
outermost frame, instead continuing until it hits garbage.  This is
sensitive to the operating system and thread library.

*** Threads

threads/1650: manythreads.exp

On GNU/Linux systems that use the old LinuxThreads thread library, a
program rapidly creating and deleting threads can confuse GDB leading
to an internal error.

This problem does not occur on newer systems that use the NPTL
library, and did not occur with GDB 6.1.