Created attachment 14491 [details] 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
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; }
https://sourceware.org/pipermail/gdb-patches/2022-December/194613.html
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
Fixed.
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