[Bug c++/98930] New: ICE when using function local static constexpr variable at runtime

[Bug c++/98930] New: ICE when using function local static constexpr variable at runtime

[matthieum.147192 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98930

            Bug ID: 98930
           Summary: ICE when using function local static constexpr
                    variable at runtime
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: matthieum.147192 at gmail dot com
  Target Milestone: ---

The following code crashes gcc trunk (11.0) and produces a linker error on
prior versions -- from 7.2 to 10.2.1 -- from -O0 to -O3.

Link to compiler explorer: https://godbolt.org/z/qox73Y



Self-sufficient code snippet:

template <char const* format>
class Source {
public:
    explicit Source() noexcept {
        asm volatile("" : : "r,m"(format) : "memory");
    }

    int index() const noexcept { return 0; }
};

template <typename T>
T impl() {
    static constexpr const char FORMAT_[] = "Hello, {}!";
    static Source<FORMAT_> const SOURCE{};

    return SOURCE.index();
}

int main() {
    return impl<int>();
}



GCC trunk crash:

<source>: In instantiation of 'Source<format>::Source() [with const char*
format = (& FORMAT_)]':
<source>:4:14:   required from here
<source>:4:14: internal compiler error: in discriminator_for_local_entity, at
cp/mangle.c:1949
    4 |     explicit Source() noexcept {
      |              ^~~~~~
0x1ce5ce9 internal_error(char const*, ...)
        ???:0
0x6b6f1b fancy_abort(char const*, int, char const*)
        ???:0
0x812f3b mangle_decl(tree_node*)
        ???:0
0x135b052 decl_assembler_name(tree_node*)
        ???:0
0x138e478 assign_assembler_name_if_needed(tree_node*)
        ???:0
0xb48015 cgraph_node::analyze()
        ???:0
0xb4c6dd symbol_table::finalize_compilation_unit()
        ???:0



GCC 10.2 linker error:

/opt/compiler-explorer/gcc-10.2.0/bin/../lib/gcc/x86_64-linux-gnu/10.2.0/../../../../x86_64-linux-gnu/bin/ld:
/tmp/cc6YCcxH.o: in function `_ZN6SourceIXadL_ZZ4implIT_ES1_vE7FORMAT_EEEC1Ev':
/home/ce/<source>:5: undefined reference to `_ZZ4implIT_ES0_vE7FORMAT_'
collect2: error: ld returned 1 exit status



Other compilers: ICE on Clang 11.0, Works on Clang (trunk).



In the same area (local static constexpr) I found 2 bug reports:

- https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95686
- https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98288 (which I reported)


Regards.

[Bug c++/98930] ICE when using function local static constexpr variable at runtime

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98930

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 98288 has been marked as a duplicate of this bug. ***

[Bug c++/98930] ICE when using function local static constexpr variable at runtime

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98930

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2021-10-02
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

[Bug c++/98930] ICE with static variable in template function used as template argument

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98930

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|ICE when using function     |ICE with static variable in
                   |local static constexpr      |template function used as
                   |variable at runtime         |template argument

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Shortest testcase:
template <int* format>
struct g { g() { *format =1; } };

template <int>
void impl() {
    static int i=1;
    static g<&i> h{};
}

int main() {
  impl<0>();
  return 0;
}

[Bug c++/98930] ICE with static variable in template function used as template argument

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98930

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:f3930418cb82000fae3cb4e98e870428800cf295

commit r12-4186-gf3930418cb82000fae3cb4e98e870428800cf295
Author: Patrick Palka <ppalka@redhat.com>
Date:   Tue Oct 5 09:50:02 2021 -0400

    c++: templated static local var has value-dep addr [PR98930]

    Here uses_template_parms returns false for the dependent type A<&impl::i>,
    which causes tsubst_aggr_type to think it's non-dependent and not bother
    substituting into it, leading to breakage.

    This patch fixes this by making has_value_dependent_address also return
    true for templated static local variables.

            PR c++/98930

    gcc/cp/ChangeLog:

            * pt.c (has_value_dependent_address): Return true for a static
            local variable from a function template.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp1z/nontype4.C: New test.
            * g++.dg/cpp1z/nontype4a.C: New test.

[Bug c++/98930] ICE with static variable in template function used as template argument

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98930

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |12.0
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED
                 CC|                            |ppalka at gcc dot gnu.org

--- Comment #5 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed for GCC 12, thanks for the bug report.