[Bug c++/100616] New: [modules] ICE when a class template taking a non-type template argument is used both inside and outside the defining module

[Bug c++/100616] New: [modules] ICE when a class template taking a non-type template argument is used both inside and outside the defining module

[amorvincitomnia.iw at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100616

            Bug ID: 100616
           Summary: [modules] ICE when a class template taking a non-type
                    template argument is used both inside and outside the
                    defining module
           Product: gcc
           Version: 11.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: amorvincitomnia.iw at gmail dot com
  Target Milestone: ---

See it live: https://wandbox.org/permlink/QUKvRN5GI1feSldA


Minimal code to reproduce ICE:

// test.cc
export module test;

export
{
    struct A{};
    template <auto x>
    struct C {
    };

    C<A{}> c1;
}

// prog.cc
import test;
C<1> c2;



Compile this with:

$ g++ "-std=c++20" "-fmodules-ts" "test.cc" "prog.cc"



Generates:

In module test, imported at prog.cc:2:
test.cc: In instantiation of 'struct C@test<1>':
prog.cc:3:6:   required from here
test.cc:8:12: internal compiler error: Segmentation fault
    8 |     struct C {
      |            ^
0xcac40f crash_signal
        ../../source/gcc/toplev.c:327
0x7e6673 comptypes(tree_node*, tree_node*, int)
        ../../source/gcc/cp/typeck.c:1544
0x7e6673 comptypes(tree_node*, tree_node*, int)
        ../../source/gcc/cp/typeck.c:1527
0x6a894f complete_vars(tree_node*)
        ../../source/gcc/cp/decl.c:17761
0x65f97b finish_struct_1(tree_node*)
        ../../source/gcc/cp/class.c:7505
0x7b1014 instantiate_class_template_1
        ../../source/gcc/cp/pt.c:12248
0x7b1e42 instantiate_class_template(tree_node*)
        ../../source/gcc/cp/pt.c:12288
0x7e380b complete_type(tree_node*)
        ../../source/gcc/cp/typeck.c:143
0x7e380b complete_type(tree_node*)
        ../../source/gcc/cp/typeck.c:111
0x6a1aeb start_decl_1(tree_node*, bool)
        ../../source/gcc/cp/decl.c:5677
0x6b283f start_decl(cp_declarator const*, cp_decl_specifier_seq*, int,
tree_node*, tree_node*, tree_node**)
        ../../source/gcc/cp/decl.c:5643
0x771343 cp_parser_init_declarator
        ../../source/gcc/cp/parser.c:21759
0x74fac4 cp_parser_simple_declaration
        ../../source/gcc/cp/parser.c:14464
0x779cb5 cp_parser_declaration
        ../../source/gcc/cp/parser.c:14161
0x77a98e cp_parser_toplevel_declaration
        ../../source/gcc/cp/parser.c:14190
0x77a98e cp_parser_translation_unit
        ../../source/gcc/cp/parser.c:4942
0x77a98e c_parse_file()
        ../../source/gcc/cp/parser.c:45372
0x84b46d c_common_parse_file()
        ../../source/gcc/c-family/c-opts.c:1218
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.


Reproduces in both g++ 11.1.0 and 12.0.0 20210510.

[Bug c++/100616] [modules] ICE when a variable of class taking a non-type template argument is defined both inside and outside the module

[amorvincitomnia.iw at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100616

--- Comment #1 from wang ivor <amorvincitomnia.iw at gmail dot com> ---
Seems like the same bug happens whenever you use a class template with a
non-type template argument in two modules with dependency. This seems to be a
pretty serious bug that renders non-type template argument basically unusable
inside modules.

[Bug c++/100616] [modules] ICE when a variable of class taking a non-type template argument is defined both inside and outside the module

[amorvincitomnia.iw at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100616

--- Comment #2 from wang ivor <amorvincitomnia.iw at gmail dot com> ---
One workaround I found is to always use templates to refer to C inside modules
and only ever instantiate them in the outermost translation units. 

Or, if you only instantiate C with template arguments of primitive types (e.g.
int, char, pointer types of primitive types, etc.) this bug doesn't happen.

[Bug c++/100616] [modules] ICE when a variable of class taking a non-type template argument is defined both inside and outside the module

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100616

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Nathan Sidwell <nathan@gcc.gnu.org>:

https://gcc.gnu.org/g:a1f7f9541c2b20eb44750b9c15cd831c62d67f21

commit r13-2953-ga1f7f9541c2b20eb44750b9c15cd831c62d67f21
Author: Nathan Sidwell <nathan@acm.org>
Date:   Wed Sep 28 09:21:14 2022 -0700

    c++: import/export NTTP objects

    This adds smarts to the module machinery to handle NTTP object
    VAR_DECLs.  Like typeinfo objects, these must be ignored in the symbol
    table, streamed specially and recreated on stream in.

            gcc/cp/
            PR c++/100616
            * module.cc (enum tree_tag): Add tt_nttp_var.
            (trees_out::decl_node): Handle NTTP objects.
            (trees_in::tree_node): Handle tt_nttp_var.
            (depset::hash::add_binding_entry): Skip NTTP objects.

            gcc/testsuite/
            PR c++/100616
            * g++.dg/modules/100616_a.H: New.
            * g++.dg/modules/100616_b.C: New.
            * g++.dg/modules/100616_c.C: New.
            * g++.dg/modules/100616_d.C: New.

[Bug c++/100616] [modules] ICE when a variable of class taking a non-type template argument is defined both inside and outside the module

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100616

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
   Target Milestone|---                         |13.0
                 CC|                            |ppalka at gcc dot gnu.org
             Status|UNCONFIRMED                 |RESOLVED

--- Comment #4 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed

[Bug c++/100616] [modules] ICE when a variable of class taking a non-type template argument is defined both inside and outside the module

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100616

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |johelegp at gmail dot com

--- Comment #5 from Patrick Palka <ppalka at gcc dot gnu.org> ---
*** Bug 105044 has been marked as a duplicate of this bug. ***