[Bug c++/111592] New: ICE on expanding argument pack into variadic constructor

[Bug c++/111592] New: ICE on expanding argument pack into variadic constructor

[yankel-pro at scialom dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111592

            Bug ID: 111592
           Summary: ICE on expanding argument pack into variadic
                    constructor
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: yankel-pro at scialom dot org
  Target Milestone: ---

GCC raises an Internal Compiler Error in c_common_parse_file() when
(indirectly, see source) expanding an argument pack into a variadic
constructor.

$ g++ --version
g++
(Compiler-Explorer-Build-gcc-1eb80f78f114f6582c349f75e08b361a0a582091-binutils-2.40)
14.0.0 20230925 (experimental)

$ cat source
struct ignore
{ ignore(...) {} };

template<class... Args>
void
InternalCompilerError(Args... args)
{ ignore{ ignore(args) ... }; }

int
main()
{ InternalCompilerError(0, 0); }

$ g++ -c source
<source>: In instantiation of 'void InternalCompilerError(Args ...) [with Args
= {int, int}]':
<source>:11:24:   required from here
<source>:7:3: internal compiler error: in finish_expr_stmt, at
cp/semantics.cc:910
    7 | { ignore{ ignore(args) ... }; }
      |   ^~~~~~
0x251c8ee internal_error(char const*, ...)
        ???:0
0xae8dda fancy_abort(char const*, int, char const*)
        ???:0
0xcfa8f8 instantiate_decl(tree_node*, bool, bool)
        ???:0
0xd2dcbb instantiate_pending_templates(int)
        ???:0
0xbded50 c_parse_final_cleanups()
        ???:0
0xe149d8 c_common_parse_file()
        ???:0

Found on Compiler Explorer <https://godbolt.org/z/M788xE44z>.

[Bug c++/111592] [11/12/13/14 Regression] ICE on expanding argument pack into variadic constructor

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111592

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|ICE on expanding argument   |[11/12/13/14 Regression]
                   |pack into variadic          |ICE on expanding argument
                   |constructor                 |pack into variadic
                   |                            |constructor
   Last reconfirmed|                            |2023-09-25
   Target Milestone|---                         |11.5
      Known to work|                            |5.1.0, 5.5.0
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
      Known to fail|                            |6.1.0, 6.2.0
           Keywords|                            |ice-on-valid-code

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

[Bug c++/111592] [11/12/13/14 Regression] ICE on expanding argument pack into variadic constructor

[law at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111592

Jeffrey A. Law <law at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1
                 CC|                            |law at gcc dot gnu.org

[Bug c++/111592] [11/12/13/14 Regression] ICE on expanding argument pack into variadic constructor

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111592

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jakub at gcc dot gnu.org
           Priority|P1                          |P2

--- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 6-13 has been released with this bug, so P2.

[Bug c++/111592] [11/12/13/14 Regression] ICE on expanding argument pack into variadic constructor

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111592

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

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

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Started with r6-6795-g0fd9d4921f7ba2.  But that's only adding an assert so the
problem was probably latent.

[Bug c++/111592] [11/12/13/14/15 Regression] ICE on expanding argument pack into variadic constructor

[simartin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111592

Simon Martin <simartin at gcc dot gnu.org> changed:

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

--- Comment #4 from Simon Martin <simartin at gcc dot gnu.org> ---
Working on it.

[Bug c++/111592] [11/12/13/14/15 Regression] ICE on expanding argument pack into variadic constructor

[simartin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111592

--- Comment #5 from Simon Martin <simartin at gcc dot gnu.org> ---
The bug was introduced via
https://gcc.gnu.org/git/gitweb.cgi?p=gcc.git;h=9efe5fbde1e8; I will submit a
patch momentarily.

[Bug c++/111592] [12/13/14/15 Regression] ICE on expanding argument pack into variadic constructor

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111592

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|11.5                        |12.5

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 11 branch is being closed.

[Bug c++/111592] [12/13/14/15 Regression] ICE on expanding argument pack into variadic constructor

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111592

--- Comment #7 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Simon Martin <simartin@gcc.gnu.org>:

https://gcc.gnu.org/g:a1999cbc816ecd382c7af4ca44153379de49dcaf

commit r15-2792-ga1999cbc816ecd382c7af4ca44153379de49dcaf
Author: Simon Martin <simon@nasilyan.com>
Date:   Wed Aug 7 12:45:12 2024 +0200

    c++: Fix ICE on valid involving variadic constructor [PR111592]

    We currently ICE upon the following valid code, due to the fix made through
    commit 9efe5fbde1e8

    === cut here ===
    struct ignore { ignore(...) {} };
    template<class... Args>
    void InternalCompilerError(Args... args)
    { ignore{ ignore(args) ... }; }
    int main() { InternalCompilerError(0, 0); }
    === cut here ===

    Change 9efe5fbde1e8 avoids infinite recursion in build_over_call by
returning
    error_mark_node if one invokes ignore::ignore(...) with an argument of type
    ignore, because otherwise we end up calling convert_arg_to_ellipsis for
that
    argument, and recurse into build_over_call with the exact same parameters.

    This patch tightens the condition to only return error_mark_node if there's
one
    and only one parameter to the call being processed - otherwise we won't
    infinitely recurse.

    Successfully tested on x86_64-pc-linux-gnu.

            PR c++/111592

    gcc/cp/ChangeLog:

            * call.cc (build_over_call): Only error out if there's a single
            parameter of type A in a call to A::A(...).

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp0x/variadic186.C: New test.

[Bug c++/111592] [12/13/14/15 Regression] ICE on expanding argument pack into variadic constructor

[simartin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111592

Simon Martin <simartin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED
   Target Milestone|12.5                        |15.0

--- Comment #8 from Simon Martin <simartin at gcc dot gnu.org> ---
Fixed on trunk.