[Bug c++/108744] New: error message when trying to use structured bindings in static member declaration could be cleaner

[Bug c++/108744] New: error message when trying to use structured bindings in static member declaration could be cleaner

[barry.revzin at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108744

            Bug ID: 108744
           Summary: error message when trying to use structured bindings
                    in static member declaration could be cleaner
           Product: gcc
           Version: 13.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: barry.revzin at gmail dot com
  Target Milestone: ---

Consider:

struct X {
    int i, j;
};

struct C {
    static auto [a, b] = X{1, 2};
};


This is ill-formed, but the error is currently:

<source>:6:17: error: expected unqualified-id before '[' token
    6 |     static auto [a, b] = X{1, 2};
      |                 ^

clang, in contrast, says:

<source>:6:17: error: decomposition declaration not permitted in this context
    static auto [a, b] = X{1, 2};
                ^~~~~~

Which is a lot clearer. I think ideally the error states explicitly that
structured bindings can't be used in static data member declarations.

[Bug c++/108744] error message when trying to use structured bindings in static member declaration could be cleaner

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108744

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2023-02-09
             Status|UNCONFIRMED                 |NEW

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

[Bug c++/108744] error message when trying to use structured bindings in static member declaration could be cleaner

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108744

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

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

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Looks like it doesn't even need to be static.  Are structured bindings
generally banned in data members?

[Bug c++/108744] error message when trying to use structured bindings in static member declaration could be cleaner

[barry.revzin at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108744

--- Comment #3 from Barry Revzin <barry.revzin at gmail dot com> ---
Yeah, they're banned in non-static data members also. But there, we just can't
have any "auto" non-static data members, whereas you can have "auto" static
data members (just not structured bindings).