[Bug c++/95451] New: [8/9/10 regression] ICE for lambda capturing this and calling operator()

[Bug c++/95451] New: [8/9/10 regression] ICE for lambda capturing this and calling operator()

[max.kanold@nu-cost.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95451

            Bug ID: 95451
           Summary: [8/9/10 regression] ICE for lambda capturing this and
                    calling operator()
           Product: gcc
           Version: 10.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: max.kanold@nu-cost.com
  Target Milestone: ---

The following legal code will lead to an Internal Compiler Error, see
https://godbolt.org/z/PoyMEL

================================
struct A {
    template<typename>
    void function_with_lambda() {
        [this](auto) {
            /*this->*/operator()();
        };
    }

    void operator()() {}
};

int main() {
    A{}.function_with_lambda<void>();
}
================================

A simple workaround is explicitely adding "this->" before the function call.
This is familiar to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86594, where
the same workaround prevents the ICE.

[Bug c++/95451] [8/9/10 regression] ICE for lambda capturing this and calling operator()

[max.kanold@nu-cost.com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95451

--- Comment #1 from Max <max.kanold@nu-cost.com> ---
I just noted this is a duplicate of
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90480, although the other bug
report neither mentions the workaround nor 86594. I guess I need to improve my
search skills :/

[Bug c++/95451] [8/9/10 regression] ICE for lambda capturing this and calling operator() since r8-2720-gf44a8dd56f5bfbd0

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95451

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at gcc dot gnu.org,
                   |                            |marxin at gcc dot gnu.org
             Status|UNCONFIRMED                 |NEW
            Summary|[8/9/10 regression] ICE for |[8/9/10 regression] ICE for
                   |lambda capturing this and   |lambda capturing this and
                   |calling operator()          |calling operator() since
                   |                            |r8-2720-gf44a8dd56f5bfbd0
           Keywords|                            |ice-on-valid-code
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2020-06-01

--- Comment #2 from Martin Liška <marxin at gcc dot gnu.org> ---
Confirmed, started with r8-2720-gf44a8dd56f5bfbd0.

[Bug c++/95451] [8/9/10/11 regression] ICE for lambda capturing this and calling operator() since r8-2720-gf44a8dd56f5bfbd0

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95451

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |8.5
            Summary|[8/9/10 regression] ICE for |[8/9/10/11 regression] ICE
                   |lambda capturing this and   |for lambda capturing this
                   |calling operator() since    |and calling operator()
                   |r8-2720-gf44a8dd56f5bfbd0   |since
                   |                            |r8-2720-gf44a8dd56f5bfbd0

[Bug c++/95451] [8/9/10/11 regression] ICE for lambda capturing this and calling operator() since r8-2720-gf44a8dd56f5bfbd0

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95451

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Bisected to a different rev, so maybe not a dup after all.

[Bug c++/95451] [8/9/10/11 regression] ICE for lambda capturing this and calling operator() since r8-2720-gf44a8dd56f5bfbd0

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95451

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

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

--- Comment #4 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
We indeed ICE on:
struct A {
  template<typename>
  void foo() {
    [this](auto) { operator()(); }(0);
  }
  void operator()() {}
};

int main() {
  A{}.foo<void>();
}
accept:
struct A {
  template<typename>
  void foo() {
    [this](int) { operator()(); }(0);
  }
  void operator()() {}
};

int main() {
  A{}.foo<int>();
}
and reject:
struct A {
  void foo() {
    [this](auto) { operator()(); }(0);
  }
  void operator()() {}
};

int main() {
  A{}.foo();
}
while clang++ accepts all 3. With this->operator()() instead of operator()()
all 3 are accepted too indeed.

[Bug c++/95451] [8/9/10/11 regression] ICE for lambda capturing this and calling operator() since r8-2720-gf44a8dd56f5bfbd0

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95451

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

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

--- Comment #5 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 50256
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50256&action=edit
gcc11-pr95451.patch

Untested fix.

[Bug c++/95451] [8/9/10/11 regression] ICE for lambda capturing this and calling operator() since r8-2720-gf44a8dd56f5bfbd0

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95451

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:27f9a87886d48448f83e0e559dcf028b1a4a4ec6

commit r11-7418-g27f9a87886d48448f83e0e559dcf028b1a4a4ec6
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Feb 26 10:43:28 2021 +0100

    c++: Fix operator() lookup in lambdas [PR95451]

    During name lookup, name-lookup.c uses:
                if (!(!iter->type && HIDDEN_TYPE_BINDING_P (iter))
                    && (bool (want & LOOK_want::HIDDEN_LAMBDA)
                        || !is_lambda_ignored_entity (iter->value))
                    && qualify_lookup (iter->value, want))
                  binding = iter->value;
    Unfortunately as the following testcase shows, this doesn't work in
    generic lambdas, where we on the auto b = ... lambda ICE and on the
    auto d = lambda reject it even when it should be valid.  The problem
    is that the binding doesn't have a FUNCTION_DECL with
    LAMBDA_FUNCTION_P for the operator(), but an OVERLOAD with
    TEMPLATE_DECL for such FUNCTION_DECL.

    The following patch fixes that in is_lambda_ignored_entity, other
    possibility would be to do that before calling is_lambda_ignored_entity
    in name-lookup.c.

    2021-02-26  Jakub Jelinek  <jakub@redhat.com>

            PR c++/95451
            * lambda.c (is_lambda_ignored_entity): Before checking for
            LAMBDA_FUNCTION_P, use OVL_FIRST.  Drop FUNCTION_DECL check.

            * g++.dg/cpp1y/lambda-generic-95451.C: New test.

[Bug c++/95451] [8/9/10 regression] ICE for lambda capturing this and calling operator() since r8-2720-gf44a8dd56f5bfbd0

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95451

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[8/9/10/11 regression] ICE  |[8/9/10 regression] ICE for
                   |for lambda capturing this   |lambda capturing this and
                   |and calling operator()      |calling operator() since
                   |since                       |r8-2720-gf44a8dd56f5bfbd0
                   |r8-2720-gf44a8dd56f5bfbd0   |

--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed on the trunk so far.

[Bug c++/95451] [8/9/10 regression] ICE for lambda capturing this and calling operator() since r8-2720-gf44a8dd56f5bfbd0

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95451

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sfranzen85 at hotmail dot com

--- Comment #8 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
*** Bug 97214 has been marked as a duplicate of this bug. ***

[Bug c++/95451] [8/9/10 regression] ICE for lambda capturing this and calling operator() since r8-2720-gf44a8dd56f5bfbd0

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95451

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |gcc at olupton dot com

--- Comment #9 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
*** Bug 90480 has been marked as a duplicate of this bug. ***

[Bug c++/95451] [8/9/10 regression] ICE for lambda capturing this and calling operator() since r8-2720-gf44a8dd56f5bfbd0

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95451

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |fiesh at zefix dot tv

--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
*** Bug 99640 has been marked as a duplicate of this bug. ***

[Bug c++/95451] [8/9/10 regression] ICE for lambda capturing this and calling operator() since r8-2720-gf44a8dd56f5bfbd0

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95451

--- Comment #11 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:8f9308936cf1df134d5aac1f890eb67266530ab5

commit r10-9477-g8f9308936cf1df134d5aac1f890eb67266530ab5
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Feb 26 10:43:28 2021 +0100

    c++: Fix operator() lookup in lambdas [PR95451]

    During name lookup, name-lookup.c uses:
                if (!(!iter->type && HIDDEN_TYPE_BINDING_P (iter))
                    && (bool (want & LOOK_want::HIDDEN_LAMBDA)
                        || !is_lambda_ignored_entity (iter->value))
                    && qualify_lookup (iter->value, want))
                  binding = iter->value;
    Unfortunately as the following testcase shows, this doesn't work in
    generic lambdas, where we on the auto b = ... lambda ICE and on the
    auto d = lambda reject it even when it should be valid.  The problem
    is that the binding doesn't have a FUNCTION_DECL with
    LAMBDA_FUNCTION_P for the operator(), but an OVERLOAD with
    TEMPLATE_DECL for such FUNCTION_DECL.

    The following patch fixes that in is_lambda_ignored_entity, other
    possibility would be to do that before calling is_lambda_ignored_entity
    in name-lookup.c.

    2021-02-26  Jakub Jelinek  <jakub@redhat.com>

            PR c++/95451
            * lambda.c (is_lambda_ignored_entity): Before checking for
            LAMBDA_FUNCTION_P, use OVL_FIRST.  Drop FUNCTION_DECL check.

            * g++.dg/cpp1y/lambda-generic-95451.C: New test.

    (cherry picked from commit 27f9a87886d48448f83e0e559dcf028b1a4a4ec6)

[Bug c++/95451] [8/9 regression] ICE for lambda capturing this and calling operator() since r8-2720-gf44a8dd56f5bfbd0

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95451

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[8/9/10 regression] ICE for |[8/9 regression] ICE for
                   |lambda capturing this and   |lambda capturing this and
                   |calling operator() since    |calling operator() since
                   |r8-2720-gf44a8dd56f5bfbd0   |r8-2720-gf44a8dd56f5bfbd0

--- Comment #12 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed for 10.3 too.

[Bug c++/95451] [8/9 regression] ICE for lambda capturing this and calling operator() since r8-2720-gf44a8dd56f5bfbd0

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95451

--- Comment #13 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:1f7f4e1118ab7f1118a2977303b672ecec439a6b

commit r9-9427-g1f7f4e1118ab7f1118a2977303b672ecec439a6b
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Feb 26 10:43:28 2021 +0100

    c++: Fix operator() lookup in lambdas [PR95451]

    During name lookup, name-lookup.c uses:
                if (!(!iter->type && HIDDEN_TYPE_BINDING_P (iter))
                    && (bool (want & LOOK_want::HIDDEN_LAMBDA)
                        || !is_lambda_ignored_entity (iter->value))
                    && qualify_lookup (iter->value, want))
                  binding = iter->value;
    Unfortunately as the following testcase shows, this doesn't work in
    generic lambdas, where we on the auto b = ... lambda ICE and on the
    auto d = lambda reject it even when it should be valid.  The problem
    is that the binding doesn't have a FUNCTION_DECL with
    LAMBDA_FUNCTION_P for the operator(), but an OVERLOAD with
    TEMPLATE_DECL for such FUNCTION_DECL.

    The following patch fixes that in is_lambda_ignored_entity, other
    possibility would be to do that before calling is_lambda_ignored_entity
    in name-lookup.c.

    2021-02-26  Jakub Jelinek  <jakub@redhat.com>

            PR c++/95451
            * lambda.c (is_lambda_ignored_entity): Before checking for
            LAMBDA_FUNCTION_P, use OVL_FIRST.  Drop FUNCTION_DECL check.

            * g++.dg/cpp1y/lambda-generic-95451.C: New test.

    (cherry picked from commit 8f9308936cf1df134d5aac1f890eb67266530ab5)

[Bug c++/95451] [8/9 regression] ICE for lambda capturing this and calling operator() since r8-2720-gf44a8dd56f5bfbd0

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95451

--- Comment #14 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-8 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:a42f679e87e5982788981439d9d1ff2fdd7323e9

commit r8-10892-ga42f679e87e5982788981439d9d1ff2fdd7323e9
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Feb 26 10:43:28 2021 +0100

    c++: Fix operator() lookup in lambdas [PR95451]

    During name lookup, name-lookup.c uses:
                if (!(!iter->type && HIDDEN_TYPE_BINDING_P (iter))
                    && (bool (want & LOOK_want::HIDDEN_LAMBDA)
                        || !is_lambda_ignored_entity (iter->value))
                    && qualify_lookup (iter->value, want))
                  binding = iter->value;
    Unfortunately as the following testcase shows, this doesn't work in
    generic lambdas, where we on the auto b = ... lambda ICE and on the
    auto d = lambda reject it even when it should be valid.  The problem
    is that the binding doesn't have a FUNCTION_DECL with
    LAMBDA_FUNCTION_P for the operator(), but an OVERLOAD with
    TEMPLATE_DECL for such FUNCTION_DECL.

    The following patch fixes that in is_lambda_ignored_entity, other
    possibility would be to do that before calling is_lambda_ignored_entity
    in name-lookup.c.

    2021-02-26  Jakub Jelinek  <jakub@redhat.com>

            PR c++/95451
            * lambda.c (is_lambda_ignored_entity): Before checking for
            LAMBDA_FUNCTION_P, use OVL_FIRST.  Drop FUNCTION_DECL check.

            * g++.dg/cpp1y/lambda-generic-95451.C: New test.

    (cherry picked from commit 8f9308936cf1df134d5aac1f890eb67266530ab5)

[Bug c++/95451] [8/9 regression] ICE for lambda capturing this and calling operator() since r8-2720-gf44a8dd56f5bfbd0

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95451

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED

--- Comment #15 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed.

[Bug c++/95451] [8/9 regression] ICE for lambda capturing this and calling operator() since r8-2720-gf44a8dd56f5bfbd0

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95451

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

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

--- Comment #16 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 85171 has been marked as a duplicate of this bug. ***