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From: "sgk at troutmask dot apl.washington.edu" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug fortran/110644] Error in gfc_format_decoder
Date: Wed, 18 Oct 2023 17:03:22 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D110644

--- Comment #5 from Steve Kargl <sgk at troutmask dot apl.washington.edu> -=
--
On Wed, Oct 18, 2023 at 03:56:32PM +0000, aluaces at udc dot es wrote:
> --- Comment #4 from Alberto Luaces <aluaces at udc dot es> ---
> I got the same error in almost the same circumstances (crash in error.cc:=
1078).
>=20
> I have a large codebase and I could not prepare a minimal testcase, but I=
 have
> built gfortran 13 from source with the aim to debug the crash.
>=20
> Hoewever, even I set "set follow-fork-mode children", f951 crashes and I =
cannot
> navigate through the backtrace nor see the arguments of the functions.
>=20
> Is there any reference for debugging gcc in order to send some useful
> information to this bug?
>=20

If you've built 13 and still have the source files and build=20
directory, then locate the installed l f951.  For me, I have=20

${HOME}/work/x/libexec/gcc/x86_64-unknown-freebsd14.0/14.0.0/f951

In following, I'm going to use ${PATH} for the above path.

Go to the directory where your project dies.  Suppose it is=20
compiling foo.f90 when it crashes.  Do the following.

gdb ${PATH}/f951

(gdb) b error.cc:1078
(gdb) run foo.f90

Line 1078 is=20

        gcc_assert (loc->nextc - loc->lb->line >=3D 0);

so the source file information looks corrupt.  You may need to=20
continue the process a few to generate the crash, i.e.,

(gdb) c

<when it crashes>

(gdb) bt

This will generate a backtrace.  Post that.=