[Bug c++/104995] New: access checking for function pointer template parameters takes place at call site

[Bug c++/104995] New: access checking for function pointer template parameters takes place at call site

[mawww at kakoune dot org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104995

            Bug ID: 104995
           Summary: access checking for function pointer template
                    parameters takes place at call site
           Product: gcc
           Version: 11.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mawww at kakoune dot org
  Target Milestone: ---

The following code

```
template<auto F>
void func() {
    auto lambda = [&](auto&& s) { F(s); };
    lambda(0);
}

struct S {
    void f() { func<S::g>(); }

private:
    static void g(int) {}
};
```

Fails to compile on g++ 11.2.1 with the following error:

```
test.cc: In instantiation of ‘func<S::g>()::<lambda(auto:1&&)> [with auto:1 =
int]’:
test.cc:4:11:   required from ‘void func() [with auto F = S::g]’
test.cc:8:26:   required from here
test.cc:3:36: error: ‘static void S::g(int)’ is private within this context
    3 |     auto lambda = [&](auto&& s) { F(s); };
      |                                   ~^~~
test.cc:11:17: note: declared private here
   11 |     static void g(int) {}
      |                 ^

```

Clang accepts this code, making func's body just `{ F(0); }` compiles without
errors as well.

[Bug c++/104995] access checking for function pointer template parameters takes place at call site

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104995

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |c++-lambda

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

[Bug c++/104995] access checking for function pointer template parameters takes place at call site inside a lambda

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104995

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
            Summary|access checking for         |access checking for
                   |function pointer template   |function pointer template
                   |parameters takes place at   |parameters takes place at
                   |call site                   |call site inside a lambda
           Keywords|                            |c++-lambda
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2023-01-03

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

[Bug c++/104995] [10/11/12/13 Regression] access checking for function pointer template parameters takes place at call site inside a templated (generic) lambda

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104995

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|access checking for         |[10/11/12/13 Regression]
                   |function pointer template   |access checking for
                   |parameters takes place at   |function pointer template
                   |call site inside a          |parameters takes place at
                   |templated (generic) lambda  |call site inside a
                   |                            |templated (generic) lambda
   Target Milestone|---                         |10.5
                 CC|                            |jason at gcc dot gnu.org,
                   |                            |ppalka at gcc dot gnu.org

--- Comment #3 from Patrick Palka <ppalka at gcc dot gnu.org> ---
C++14 testcase exhibiting a regression since GCC 8 / r8-2720-gf44a8dd56f5bfb:

template<void(*F)(int)>
void func() {
    auto lambda = [&](auto&& s) { F(s); };
    lambda(0);
}

struct S {
    void f() { func<S::g>(); }

private:
    static void g(int) {}
};

[Bug c++/104995] [11/12/13/14 Regression] access checking for function pointer template parameters takes place at call site inside a templated (generic) lambda

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104995

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|10.5                        |11.5

--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 10 branch is being closed.

[Bug c++/104995] [11/12/13/14 Regression] access checking for function pointer template parameters takes place at call site inside a templated (generic) lambda

[law at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104995

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |law at gcc dot gnu.org
           Priority|P3                          |P2