[Bug fortran/99798] New: ICE when compiling a variant of pr87907

[Bug fortran/99798] New: ICE when compiling a variant of pr87907

[dominiq at lps dot ens.fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99798

            Bug ID: 99798
           Summary: ICE when compiling a variant of pr87907
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dominiq at lps dot ens.fr
  Target Milestone: ---

Compiling the following variant of pr87907

module m
   interface
      module integer function g(x)
         integer, intent(in) :: x
      end
   end interface
end
submodule(m) m2
contains
   subroutine g(x)      ! { dg-error "mismatch in argument" }
     integer, intent(in) :: x
   end
end

gives

% gfc pr87907_db_2.f90
pr87907_db_2.f90:10:15:

   10 |    subroutine g(x)      ! { dg-error "mismatch in argument" }
      |               1
Error: FUNCTION attribute conflicts with SUBROUTINE attribute in 'g' at (1)
pr87907_db_2.f90:11:29:

   11 |      integer, intent(in) :: x
      |                             1
Error: Unexpected data declaration statement in CONTAINS section at (1)
f951: internal compiler error: Segmentation fault: 11

The backtrace is

* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS
(code=1, address=0x106)
  * frame #0: 0x00000001000ec2b9 f951`gfc_free_statements(p=0x00000000000000f6)
at st.c:295:9
    frame #1: 0x00000001000f53f7 f951`gfc_free_namespace(ns=0x000000014500be00)
at symbol.c:4039:23
    frame #2: 0x00000001000f5a29 f951`gfc_free_symbol(gfc_symbol*) at
symbol.c:4037:3
    frame #3: 0x00000001000f59fc f951`gfc_free_symbol(sym=0x0000000142f0ba50)
    frame #4: 0x00000001000f53b2
f951`::free_sym_tree(sym_tree=0x0000000142f0ba20) at symbol.c:3902:22
    frame #5: 0x00000001000f5400 f951`gfc_free_namespace(ns=0x000000014500a200)
at symbol.c:4041:17
    frame #6: 0x00000001000f7034 f951`gfc_symbol_done_2() at symbol.c:4037:3
    frame #7: 0x00000001000f7016 f951`gfc_symbol_done_2()
    frame #8: 0x0000000100084689 f951`gfc_done_2() at misc.c:380:21
    frame #9: 0x00000001000a422a
f951`::clean_up_modules(gsym=0x0000000142f0b600) at parse.c:6311:14
    frame #10: 0x00000001000b2e17 f951`gfc_parse_file() at parse.c:6374:20
    frame #11: 0x000000010010d987 f951`::gfc_be_parse_file() at
f95-lang.c:212:18
    frame #12: 0x0000000100d1a294 f951`::compile_file() at toplev.c:457:25
    frame #13: 0x000000010120dd9f f951`toplev::main(int, char**) at
toplev.c:2201:24
    frame #14: 0x000000010120da5e f951`toplev::main(this=0x00007ffeefbff09e,
argc=<unavailable>, argv=<unavailable>)
    frame #15: 0x000000010120ffb1 f951`main(argc=2, argv=0x00007ffeefbff0d0) at
main.c:39:22
    frame #16: 0x00007fff2066d621 libdyld.dylib`start + 1

[Bug fortran/99798] ICE when compiling a variant of pr87907

[anlauf at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99798

anlauf at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
           Keywords|                            |ice-on-invalid-code
   Last reconfirmed|                            |2021-03-27
             Status|UNCONFIRMED                 |NEW

[Bug fortran/99798] ICE when compiling a variant of pr87907

[kargl at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99798

kargl at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |kargl at gcc dot gnu.org
           Priority|P3                          |P4

--- Comment #1 from kargl at gcc dot gnu.org ---
This patch prevents the ICE.  Instead of asserting that the namespace is ready
to be freed, simply return if the reference count appears to be bogus and
gfortran has already issued one or more errors.

diff --git a/gcc/fortran/symbol.cc b/gcc/fortran/symbol.cc
index 221165d6dac..8e48cbba2ca 100644
--- a/gcc/fortran/symbol.cc
+++ b/gcc/fortran/symbol.cc
@@ -27,7 +27,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "parse.h"
 #include "match.h"
 #include "constructor.h"
-
+#include "diagnostic.h"  /* Access to errorcount in gfc_free_namespace ().  */

 /* Strings for all symbol attributes.  We use these for dumping the
    parse tree, in error messages, and also when reading and writing
@@ -4043,7 +4043,7 @@ gfc_free_namespace (gfc_namespace *&ns)
     return;

   ns->refs--;
-  if (ns->refs > 0)
+  if (ns->refs > 0 || (ns->refs < 0 && errorcount > 0))
     return;

   gcc_assert (ns->refs == 0);

[Bug fortran/99798] ICE when compiling a variant of pr87907

[mikael at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99798

Mikael Morin <mikael at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mikael at gcc dot gnu.org

--- Comment #2 from Mikael Morin <mikael at gcc dot gnu.org> ---
Created attachment 55524
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55524&action=edit
Draft patch

I haven't completely nailed it down, but it seems that the reason for this is
the obscure condition in gfc_release_symbol to break cycles.
It triggers on the symbol for g imported from the module.  The symbol has 2
references,
one for the submodule namespace holding it, one for subroutine namespace that
is being freed.

[Bug fortran/99798] ICE when compiling a variant of pr87907

[mikael at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99798

Mikael Morin <mikael at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |mikael at gcc dot gnu.org

--- Comment #3 from Mikael Morin <mikael at gcc dot gnu.org> ---
I'm working on it.

[Bug fortran/99798] ICE when compiling a variant of pr87907

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99798

--- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Mikael Morin <mikael@gcc.gnu.org>:

https://gcc.gnu.org/g:38d1761c0c94b77a081ccc180d6e039f7a670468

commit r15-698-g38d1761c0c94b77a081ccc180d6e039f7a670468
Author: Mikael Morin <mikael@gcc.gnu.org>
Date:   Sun May 12 15:16:23 2024 +0200

    fortran: Assume there is no cyclic reference with submodule symbols
[PR99798]

    This prevents a premature release of memory with procedure symbols from
    submodules, causing random compiler crashes.

    The problem is a fragile detection of cyclic references, which can match
    with procedures host-associated from a module in submodules, in cases where
it
    shouldn't.  The formal namespace is released, and with it the dummy
arguments
    symbols of the procedure.  But there is no cyclic reference, so the
procedure
    symbol itself is not released and remains, with pointers to its dummy
arguments
    now dangling.

    The fix adds a condition to avoid the case, and refactors to a new
predicate
    by the way.  Part of the original condition is also removed, for lack of a
    reason to keep it.

            PR fortran/99798

    gcc/fortran/ChangeLog:

            * symbol.cc (gfc_release_symbol): Move the condition guarding
            the handling cyclic references...
            (cyclic_reference_break_needed): ... here as a new predicate.
            Remove superfluous parts.  Add a condition preventing any premature
            release with submodule symbols.

    gcc/testsuite/ChangeLog:

            * gfortran.dg/submodule_33.f08: New test.