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Release Digest: GNU, September 9, 2004

Sep 10, 2004, 04:45 (0 Talkback[s])

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GDB 6.2.1

GDB update 6.2.1 released!

Update 6.2.1 of GDB, the GNU Debugger, is now available via anonymous FTP. GDB is a source-level debugger for C, C++, Java and many other languages. GDB can target (i.e., debug programs running on) more than a dozen different processor architectures, and GDB itself can run on most popular GNU/Linux, Unix and Microsoft Windows variants.

This update fixes the following serious problems:

  • Improved i386 prologue analyzer

    The i386 prologue analyzer was improved to deal better with the prologues generated by GCC 3.3 and later. As a result GDB should produce better backtraces for code without DWARF Call Frame Info.

  • MIPS `break main; run' gave an heuristic-fence-post warning

    When attempting to run even a simple program, a warning about heuristic-fence-post being hit would be reported. This problem has been fixed.

  • MIPS IRIX 'long double' crashed GDB

    When examining a long double variable, GDB would get a segmentation fault. The crash has been fixed (but GDB 6.2 cannot correctly examine IRIX long double values).

  • VAX and "next"

    A bug in the VAX stack code was causing problems with the "next" command. This problem has been fixed.

Thanks goes to Joel Brobecker and Mark Kettenis for these fixes.

You can download GDB from Project GNU's FTP server in the directory:

ftp://ftp.gnu.org/gnu/gdb

The previous version, 6.2.1, was released roughly 6-weeks ag.

The vital stats:

Size md5sum Name
17011120 c095d01e55022fb9e609df5cfde66379 gdb-6.2.tar.gz
12819441 01871f7667345262e317a1e6e1a32768 gdb-6.2.tar.bz2

There is a web page for GDB at:

http://www.gnu.org/software/gdb/

That page includes information about GDB mailing lists (an announcement mailing list, developers discussion lists, etc.), details on how to access GDB's CVS repository, locations for development snapshots, preformatted documentation, and links to related information around the net. We will put errata notes and host-specific tips for this release on-line as any problems come up. All mailing lists archives are also browsable via the web.

Andrew Cagney
Release Manager


Known problems in GDB 6.2.1

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

  • Build problems

    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.


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