[Bug gdb/29871] New: "p tail.y ++ (diff.y / 2)" command causes crash

[Bug gdb/29871] New: "p tail.y ++ (diff.y / 2)" command causes crash

[georgebateman16 at gmail dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=29871

            Bug ID: 29871
           Summary: "p tail.y ++ (diff.y / 2)" command causes crash
           Product: gdb
           Version: 12.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: gdb
          Assignee: unassigned at sourceware dot org
          Reporter: georgebateman16 at gmail dot com
  Target Milestone: ---

Created attachment 14491
  --> https://sourceware.org/bugzilla/attachment.cgi?id=14491&action=edit
GDB session resulting in crash

While debugging a C application I entered the command "p tail.y ++ (diff.y /
2)". (This was a typo; I intended to write "+=".) This caused GDB to crash and
output the attached backtrace, starting with:

/build/gdb-YpKTRx/gdb-12.1/gdb/gdbtypes.c:3914: internal-error:
is_nocall_function: Assertion `type->code () == TYPE_CODE_FUNC || type->code ()
== TYPE_CODE_METHOD' failed.

The tail and diff objects are instances of the below struct, if that is
relevant.

typedef struct {
    int x;
    int y;
} coord;

System information (also in the attachment):

GCC VERSION

Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/x86_64-linux-gnu/12/lto-wrapper
OFFLOAD_TARGET_NAMES=nvptx-none:amdgcn-amdhsa
OFFLOAD_TARGET_DEFAULT=1
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 12.2.0-9'
--with-bugurl=file:///usr/share/doc/gcc-12/README.Bugs
--enable-languages=c,ada,c++,go,d,fortran,objc,obj-c++,m2 --prefix=/usr
--with-gcc-major-version-only --program-suffix=-12
--program-prefix=x86_64-linux-gnu- --enable-shared --enable-linker-build-id
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--libdir=/usr/lib --enable-nls --enable-clocale=gnu --enable-libstdcxx-debug
--enable-libstdcxx-time=yes --with-default-libstdcxx-abi=new
--enable-gnu-unique-object --disable-vtable-verify --enable-plugin
--enable-default-pie --with-system-zlib --enable-libphobos-checking=release
--with-target-system-zlib=auto --enable-objc-gc=auto --enable-multiarch
--disable-werror --enable-cet --with-arch-32=i686 --with-abi=m64
--with-multilib-list=m32,m64,mx32 --enable-multilib --with-tune=generic
--enable-offload-targets=nvptx-none=/build/gcc-12-lH3g9c/gcc-12-12.2.0/debian/tmp-nvptx/usr,amdgcn-amdhsa=/build/gcc-12-lH3g9c/gcc-12-12.2.0/debian/tmp-gcn/usr
--enable-offload-defaulted --without-cuda-driver --enable-checking=release
--build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 12.2.0 (Debian 12.2.0-9) 

Linux gbat-hp-linux 6.0.0-4-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.0.8-1
(2022-11-11) x86_64 GNU/Linux

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[Bug gdb/29871] "p tail.y ++ (diff.y / 2)" command causes crash

[simark at simark dot ca]

https://sourceware.org/bugzilla/show_bug.cgi?id=29871

Simon Marchi <simark at simark dot ca> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2022-12-10
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
                 CC|                            |simark at simark dot ca

--- Comment #1 from Simon Marchi <simark at simark dot ca> ---
I can reproduce.  I used this source code:

typedef struct {
    int x;
    int y;
} coord;

int main()
{
  coord tail, diff;

  return tail.x + diff.x;
}

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[Bug gdb/29871] "p tail.y ++ (diff.y / 2)" command causes crash

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29871

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tromey at sourceware dot org
           Assignee|unassigned at sourceware dot org   |tromey at sourceware dot org

--- Comment #2 from Tom Tromey <tromey at sourceware dot org> ---
https://sourceware.org/pipermail/gdb-patches/2022-December/194613.html

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[Bug gdb/29871] "p tail.y ++ (diff.y / 2)" command causes crash

[cvs-commit at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29871

--- Comment #3 from cvs-commit at gcc dot gnu.org <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Tom Tromey <tromey@sourceware.org>:

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=785545988c222f603a7a190170b04d4b971d7959

commit 785545988c222f603a7a190170b04d4b971d7959
Author: Tom Tromey <tom@tromey.com>
Date:   Sun Dec 11 12:48:07 2022 -0700

    Fix crash in is_nocall_function

    is_nocall_function anticipates only being called for a function or a
    method.  However, PR gdb/29871 points out a situation where an unusual
    expression -- but one that parses to a valid, if extremely weird,
    function call -- breaks this assumption.

    This patch changes is_nocall_function to remove this assert and
    instead simply return 'false' in this case.

    Approved-By: Simon Marchi <simon.marchi@efficios.com>
    Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29871

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[Bug gdb/29871] "p tail.y ++ (diff.y / 2)" command causes crash

[tromey at sourceware dot org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29871

Tom Tromey <tromey at sourceware dot org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
   Target Milestone|---                         |13.1
         Resolution|---                         |FIXED

--- Comment #4 from Tom Tromey <tromey at sourceware dot org> ---
Fixed.

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[Bug gdb/29871] "p tail.y ++ (diff.y / 2)" command causes crash

[alexandr.miloslavskiy at syntevo dot com]

https://sourceware.org/bugzilla/show_bug.cgi?id=29871

Alexandr Miloslavskiy <alexandr.miloslavskiy at syntevo dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |alexandr.miloslavskiy@synte
                   |                            |vo.com

--- Comment #5 from Alexandr Miloslavskiy <alexandr.miloslavskiy at syntevo dot com> ---
The problem was standing in my way in a completely useful usecase.

I was calling a function like this:
(gdb) call (void)0x00007ffff6e072a0()

The reason for calling it by address is that there is an ambiguous symbol name
for it:
1) libgcrypt.so - ps - some variable
2) libjvm.so    - ps - function I want to call, exported as non-debugging
symbol

And I didn't find a way to disambiguate them, see
https://sourceware.org/pipermail/gdb/2021-September/049677.html

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