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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: Thu, 19 Oct 2023 15:44:47 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D110644

--- Comment #7 from Steve Kargl <sgk at troutmask dot apl.washington.edu> -=
--
On Thu, Oct 19, 2023 at 08:00:27AM +0000, aluaces at udc dot es wrote:
>=20
> It says something about a non-recursive function likely calling itself.  =
I will
> inspect my source, even it is a bit too big.  Maybe a better solution wou=
ld be
> if I compiled gcc with debugging flags.  Can I just use C_FLAGS=3D"-O0 -g=
" and
> CXX_FLAGS=3D"-O0 -g" at configure time, or if is there a specific configu=
re flag?

I doubt that these options will help with this problem.  Those
are for building your application with debugging info.  The issue
is the compiler itself is dying.

> 1078            gcc_assert (loc->nextc - loc->lb->line >=3D 0);
> (gdb) bt
> #0  gfc_format_decoder (pp=3D0x2706750, text=3D0x7fffffffb840, spec=3D0x2=
708d10 "L",
> precision=3D<optimized out>, wide=3Dfalse, set_locus=3Dfalse, hash=3Dfals=
e,
> quoted=3D0x7fffffffb667, buffer_ptr=3D0x2708b00)
>     at ../../gcc-13.2.0/gcc/fortran/error.cc:1078
> #1  0x0000000001b44c0a in pp_format (pp=3D<optimized out>,
> text=3Dtext@entry=3D0x7fffffffb840) at ../../gcc-13.2.0/gcc/pretty-print.=
cc:1475
> #2  0x0000000001b34e02 in diagnostic_report_diagnostic (context=3D0x26ee3=
80
> <global_diagnostic_context>, diagnostic=3Ddiagnostic@entry=3D0x7fffffffb8=
40) at
> ../../gcc-13.2.0/gcc/diagnostic.cc:1592
> #3  0x000000000071cbc8 in gfc_report_diagnostic (diagnostic=3D0x7fffffffb=
840) at
> ../../gcc-13.2.0/gcc/fortran/error.cc:890
> #4  gfc_warning(int, const char *, typedef __va_list_tag __va_list_tag *)
> (opt=3D0,
>     gmsgid=3D0x1c9c420 "Non-RECURSIVE procedure %qs at %L is possibly cal=
ling
> itself recursively.  Declare it RECURSIVE or use %<-frecursive%>",
> ap=3Dap@entry=3D0x7fffffffb9c8)
>     at ../../gcc-13.2.0/gcc/fortran/error.cc:923
> #5  0x000000000071d287 in gfc_warning (opt=3Dopt@entry=3D0,
> gmsgid=3Dgmsgid@entry=3D0x1c9c420 "Non-RECURSIVE procedure %qs at %L is p=
ossibly
> calling itself recursively.  Declare it RECURSIVE or use %<-frecursive%>")
>     at ../../gcc-13.2.0/gcc/fortran/error.cc:954

I suspect that the locus associate with %L in the above
error message is undefined (i.e., a NULL pointer).  This
likely means expr in the next frame is missing some info.

> #6  0x00000000007a275f in resolve_procedure_expression (expr=3D0x32a9530)=
 at
> ../../gcc-13.2.0/gcc/fortran/resolve.cc:1956

Can you do=20

(gdb) up 6
(gdb) p *expr

You'll likely see expr->where is either NULL or its components are.
My sources are bit newer, resolve.cc:1974 is

  if (is_illegal_recursion (sym, gfc_current_ns))
    gfc_warning (0, "Non-RECURSIVE procedure %qs at %L is possibly calling"
                 " itself recursively.  Declare it RECURSIVE or use"
                 " %<-frecursive%>", sym->name, &expr->where);

You can try replacing &expr->where with gfc_current_locus.  I don't
remember if the & is needed with gfc_current_locus.=