[Bug c++/63192] New: non-mutable lambda capture by value on reference does not apply const

[Bug c++/63192] New: non-mutable lambda capture by value on reference does not apply const

[dacamara.cameron at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63192

            Bug ID: 63192
           Summary: non-mutable lambda capture by value on reference does
                    not apply const
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: minor
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dacamara.cameron at gmail dot com

This is an example taken directly from the standard (5.1.2.19) with a bit of
decoration for output. The last case produces false when it should be true.


int main() {
    float x, &r = x;
    std::cout<<std::boolalpha;
    [=] { // x and r are not captured (appearance in a decltype operand is not
an odr-use)
        std::cout<<std::is_same<decltype(x), float>::value<<'\n' // has type
float
        <<std::is_same<decltype((x)), float const&>::value<<'\n' // has type
float const& because this lambda
                                                                 // is not
mutable and x is an lvalue
        <<std::is_same<decltype(r), float&>::value<<'\n'         // r1 has type
float& (transformation not considered)
        <<std::is_same<decltype((r)), float const&>::value;      // r2 has type
float const&
    }();
}

[Bug c++/63192] non-mutable lambda capture by value on reference does not apply const

[ville.voutilainen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63192

Ville Voutilainen <ville.voutilainen at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-12-13
                 CC|                            |ville.voutilainen at gmail dot com
     Ever confirmed|0                           |1
      Known to fail|                            |4.8.2, 4.9.1, 5.0

--- Comment #1 from Ville Voutilainen <ville.voutilainen at gmail dot com> ---
Clang produces the expected result. A reduced testcase without the use of
iostreams would be helpful.

[Bug c++/63192] non-mutable lambda capture by value on reference does not apply const

[ville.voutilainen at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63192

--- Comment #2 from Ville Voutilainen <ville.voutilainen at gmail dot com> ---
Reduced:

template <class, class> struct same {static constexpr bool value = false;};
template <class T> struct same<T, T> {static constexpr bool value = true;};

int main() {
    float x, &r = x;
    [=] { // x and r are not captured (appearance in a decltype operand is not
an odr-use)
        static_assert(same<decltype(x), float>::value, "");
        static_assert(same<decltype((x)), float const&>::value, "");
        static_assert(same<decltype(r), float&>::value, "");
        static_assert(same<decltype((r)), float const&>::value, "");
    }();
}

[Bug c++/63192] non-mutable lambda capture by value on reference does not apply const

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63192

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |thiago at kde dot org

--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 66672 has been marked as a duplicate of this bug. ***

[Bug c++/63192] non-mutable lambda capture by value on reference does not apply const

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=63192

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |DUPLICATE
             Status|NEW                         |RESOLVED
           See Also|https://gcc.gnu.org/bugzill |
                   |a/show_bug.cgi?id=79620     |
                 CC|                            |ppalka at gcc dot gnu.org

--- Comment #8 from Patrick Palka <ppalka at gcc dot gnu.org> ---
This seems to be a dup of the recently fixed PR79620.

*** This bug has been marked as a duplicate of bug 79620 ***