[Bug c++/59766] New: c++1y: declaring friend function with 'auto' return type deduction is rejected with bogus reason

[Bug c++/59766] New: c++1y: declaring friend function with 'auto' return type deduction is rejected with bogus reason

[mizvekov at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59766

            Bug ID: 59766
           Summary: c++1y: declaring friend function with 'auto' return
                    type deduction is rejected with bogus reason
           Product: gcc
           Version: 4.8.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mizvekov at gmail dot com

Simple example showing the problem:

struct foo {
    friend auto test(const foo &) { return 0; }
};

g++ rejects this with:

test.cc:2:30: error: non-static data member declared ‘auto’
  friend auto test(const foo &) { return 0; }
>From gcc-bugs-return-440067-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Sat Jan 11 00:01:17 2014
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Subject: [Bug lto/47888] [4.6 Regression] tree check: expected array_type, have record_type in array_ref_low_bound, at expr.c:6249 / Segmentation fault
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idG888

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

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

--- Comment #11 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
We don't support 4.6 anymore so if this is only 4.6 thing, we can't do much
about it.

[Bug c++/59766] c++1y: declaring friend function with 'auto' return type deduction is rejected with bogus reason

[lucdanton at free dot fr]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59766

--- Comment #1 from lucdanton at free dot fr ---
Happens too with GCC 4.9 (20140105), as well as when using decltype(auto).

[Bug c++/59766] c++1y: declaring friend function with 'auto' return type deduction is rejected with bogus reason

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59766

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |adam at jessamine dot co.uk

--- Comment #2 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Maybe Adam can have a look.

[Bug c++/59766] c++1y: declaring friend function with 'auto' return type deduction is rejected with bogus reason

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59766

Paolo Carlini <paolo.carlini at oracle dot com> changed:

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

--- Comment #3 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Sorry.

[Bug c++/59766] c++1y: declaring friend function with 'auto' return type deduction is rejected with bogus reason

[felix at fontein dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59766

--- Comment #4 from Felix Fontein <felix at fontein dot de> ---
I can confirm this bug for GCC 4.9.0 20140604 (prerelease).

[Bug c++/59766] c++1y: declaring friend function with 'auto' return type deduction is rejected with bogus reason

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59766

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-12-05
     Ever confirmed|0                           |1

[Bug c++/59766] c++1y: declaring friend function with 'auto' return type deduction is rejected with bogus reason

[potswa at mac dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59766

--- Comment #5 from David Krauss <potswa at mac dot com> ---
Created attachment 34538
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34538&action=edit
ChangeLog entry

[Bug c++/59766] c++1y: declaring friend function with 'auto' return type deduction is rejected with bogus reason

[potswa at mac dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59766

--- Comment #6 from David Krauss <potswa at mac dot com> ---
Created attachment 34541
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=34541&action=edit
Fix: disable the error for friend declarators.

The fix is simple. Tested and submitted for approval. (I am a registered
contributor.)

I don't suppose this warrants a testcase file. If you want to exercise the
compiler, here is a more interesting case:


template< typename k >
struct t {
    friend auto leak( t );

    template< typename v >
    struct m {
        friend auto leak( t ) { return v{}; }
    };
};

int main() {
    t< int >::m< char > a;
    decltype( leak( t< int >{} ) ) b;
    static_assert ( sizeof b == 1, "" );

    t< int >::m< short > c; // error: redefinition of ‘auto leak(t<int>)’
}
>From gcc-bugs-return-474504-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Fri Jan 23 09:49:11 2015
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https://gcc.gnu.org/bugzilla/show_bug.cgi?idd511

--- Comment #18 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Author: jakub
Date: Fri Jan 23 09:47:51 2015
New Revision: 220031

URL: https://gcc.gnu.org/viewcvs?rev"0031&root=gcc&view=rev
Log:
    PR debug/64511
    * dwarf2out.c (struct dw_loc_descr_node): Add chain_next
    GTY markup.

Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/dwarf2out.h

[Bug c++/59766] c++1y: declaring friend function with 'auto' return type deduction is rejected with bogus reason

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59766

--- Comment #8 from Marc Glisse <glisse at gcc dot gnu.org> ---
(In reply to David Krauss from comment #6)
> The fix is simple. Tested and submitted for approval.

Thank you. Did you send it to gcc-patches, with jason AT redhat in Cc: ? I
can't find any email from you around that date.

https://gcc.gnu.org/contribute.html

> I don't suppose this warrants a testcase file.

Why not? It is the only way to make sure a later refactoring of the code won't
regress on this.

[Bug c++/59766] c++1y: declaring friend function with 'auto' return type deduction is rejected with bogus reason

[potswa at mac dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59766

--- Comment #9 from David Krauss <potswa at mac dot com> ---
I didn't send it to gcc-patches. It's never been necessary for me before. I
suppose I can collect the examples here into a testcase file. In the meantime,
anyone else is free to take charge and submit it on their own. The change is
just a matter of "don't do that."

[Bug c++/59766] c++1y: declaring friend function with 'auto' return type deduction is rejected with bogus reason

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59766

--- Comment #10 from Jason Merrill <jason at gcc dot gnu.org> ---
(In reply to David Krauss from comment #9)
> I didn't send it to gcc-patches. It's never been necessary for me before.

I appreciate getting direct mail about C++ patches so that I see them faster; I
didn't notice this one until today.  Also feel free to ping me if I haven't
responded after a week.

I'll check this in after GCC 5 branches.

[Bug c++/59766] c++1y: declaring friend function with 'auto' return type deduction is rejected with bogus reason

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59766

--- Comment #11 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Tue Apr 14 15:29:27 2015
New Revision: 222095

URL: https://gcc.gnu.org/viewcvs?rev=222095&root=gcc&view=rev
Log:
    PR c++/59766
    * decl.c (grokdeclarator): Do not flag friends with deduced return.

Added:
    trunk/gcc/testsuite/g++.dg/cpp1y/auto-fn26.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/decl.c

[Bug c++/59766] c++1y: declaring friend function with 'auto' return type deduction is rejected with bogus reason

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59766

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED
   Target Milestone|---                         |5.2

--- Comment #13 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed for 5.2/6.

[Bug c++/59766] c++1y: declaring friend function with 'auto' return type deduction is rejected with bogus reason

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59766

--- Comment #12 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Wed Apr 22 20:52:52 2015
New Revision: 222337

URL: https://gcc.gnu.org/viewcvs?rev=222337&root=gcc&view=rev
Log:
    PR c++/59766
    * decl.c (grokdeclarator): Do not flag friends with deduced return.

Added:
    branches/gcc-5-branch/gcc/testsuite/g++.dg/cpp1y/auto-fn26.C
Modified:
    branches/gcc-5-branch/gcc/cp/ChangeLog
    branches/gcc-5-branch/gcc/cp/decl.c

[Bug c++/59766] c++1y: declaring friend function with 'auto' return type deduction is rejected with bogus reason

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59766

--- Comment #14 from Jason Merrill <jason at gcc dot gnu.org> ---
Author: jason
Date: Thu Apr 23 13:21:06 2015
New Revision: 222365

URL: https://gcc.gnu.org/viewcvs?rev=222365&root=gcc&view=rev
Log:
    PR c++/59766
    * decl.c (grokdeclarator): Do not flag friends with deduced return.

Added:
    branches/gcc-4_9-branch/gcc/testsuite/g++.dg/cpp1y/auto-fn26.C
Modified:
    branches/gcc-4_9-branch/gcc/cp/ChangeLog
    branches/gcc-4_9-branch/gcc/cp/decl.c

[Bug c++/59766] c++1y: declaring friend function with 'auto' return type deduction is rejected with bogus reason

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59766

--- Comment #15 from Jason Merrill <jason at gcc dot gnu.org> ---
And 4.9.3.