[Bug c++/60894] New: Use of redundant struct keyword in virtual function prototype combined with using statement causes compilation error

[Bug c++/60894] New: Use of redundant struct keyword in virtual function prototype combined with using statement causes compilation error

[loose at astron dot nl]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60894

            Bug ID: 60894
           Summary: Use of redundant struct keyword in virtual function
                    prototype combined with using statement causes
                    compilation error
           Product: gcc
           Version: 4.8.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: loose at astron dot nl

The code below causes a compilation error:
t.cc:15:6: error: prototype for ‘void D::doIt(B::S&)’ does not match any in
class ‘D’

class B
{
protected:
  struct S {};
  virtual void doIt(struct S& s) = 0;
};

class D : public B
{
public:
  using B::S;
  virtual void doIt(struct S& s);
};

void D::doIt(struct S& s)
{
  (void)s;
}

This code compiles fine if I remove the redundant struct keyword in the virtual
function prototype. It also compiles fine if I remove the using declaration. It
seems as if the compiler thinks I'm forward declaring another struct S inside
the declaration of D::doIt().
>From gcc-bugs-return-449346-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Sat Apr 19 13:04:19 2014
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From: "mikpelinux at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug bootstrap/60830] [4.9 Regression] ICE on bootstrapping on cygwin
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id`830

--- Comment #28 from Mikael Pettersson <mikpelinux at gmail dot com> ---
My attempted bootstraps of 4.8.2 on Cygwin failed due to three reasons:

1. I had --disable-sjlj-exceptions, which worked with previous releases.
Dropping that and adding --disable-multilib (based on Kai's comment, not sure
it's needed in a purely 32-bit setting) made things work again.

[Cygwin's own gcc-4.8.2 is built with --disable-sjlj-exceptions however.  I
don't know why it works for them but not for us.]

2. I tried to build with make -j4, that caused strange linkage errors.
Dropping that and doing a non-parallell make made things work again.

3. The Ada bootstrap always failed with:

/home/mikpe/objdir/./gcc/xgcc -B/home/mikpe/objdir/./gcc/
-B/opt/local/gcc-4.8/i686-pc-cygwin/bin/
-B/opt/local/gcc-4.8/i686-pc-cygwin/lib/ -isystem
/opt/local/gcc-4.8/i686-pc-cygwin/include -isystem
/opt/local/gcc-4.8/i686-pc-cygwin/sys-include    -c -g -O2   -W -Wall -gnatpg
-nostdinc   g-sercom.adb -o g-sercom.o
g-sercom.adb:40:12: warning: no entities of "System.OS_Constants" are
referenced
g-sercom.adb:46:04: warning: no entities of "OSC" are referenced
g-sercom.adb:209:42: "DTR_CONTROL_ENABLE" not declared in "OS_Constants"
g-sercom.adb:211:42: "RTS_CONTROL_ENABLE" not declared in "OS_Constants"
../gcc-interface/Makefile:310: recipe for target 'g-sercom.o' failed
make[4]: *** [g-sercom.o] Error 1

This appears to be a known bug, I found a report of it in gcc-help,
http://gcc.gnu.org/ml/gcc-help/2012-10/msg00003.html, and a patch in
http://sourceforge.net/p/cygwin-ports/gcc/ci/master/tree/4.8-gcc-ada-DTR.patch.

(Ada on Cygwin uses mingw's g-sercom.adb which references those two symbols,
but s-oscons-tmplt.c only defines those symbols for mingw, not for Cygwin.  As
far as I can tell this issue is still present in 4.9 and 4.10.)

With all three adjustments I was finally able to bootstrap 4.8.2 on Cygwin.

[Bug c++/60894] Use of redundant struct keyword in virtual function prototype combined with using statement causes compilation error

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60894

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-04-22
     Ever confirmed|0                           |1

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Marcel Loose from comment #0)
> It seems as if the compiler thinks I'm forward declaring
> another struct S inside the declaration of D::doIt().

Not inside the declaration, but at global scope. That's what happens if you use
an elaborated-type-specifier such as "struct S" in a function declaration and
the type has not been declared previously (meaning the "struct" keyword is not
necessarily redundant in a function declaration).

In this case name lookup in the parameter-declaration-clause should find D::S
rather than introducing a new type.

[Bug c++/60894] [4.7/4.8/4.9/4.10 Regression] Use of redundant struct keyword in virtual function prototype combined with using statement causes compilation error

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60894

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

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

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
The regression was caused by r181359

Fabien, could you take a look please? I think the code is valid.

[Bug c++/60894] [4.7/4.8/4.9/4.10 Regression] Use of redundant struct keyword in virtual function prototype combined with using statement causes compilation error

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60894

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Reduced (whether the function is virtual or not is irrelevant):

struct B
{
  struct S {};
};

struct D : B
{
  using B::S;
  void doIt(struct S&);
};

void D::doIt(struct S&)
{
}

[Bug c++/60894] [4.7/4.8/4.9/4.10 Regression] Use of redundant struct keyword in virtual function prototype combined with using statement causes compilation error

[fabien at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60894

fabien at gcc dot gnu.org changed:

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

--- Comment #4 from fabien at gcc dot gnu.org ---
(In reply to Jonathan Wakely from comment #2)
> The regression was caused by r181359
> 
> Fabien, could you take a look please? I think the code is valid.

Thanks, I will look into it.

[Bug c++/60894] [4.7/4.8/4.9/4.10 Regression] Use of redundant struct keyword in virtual function prototype combined with using statement causes compilation error

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60894

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
           Priority|P3                          |P2
   Target Milestone|---                         |4.7.4

[Bug c++/60894] [4.7/4.8/4.9/4.10 Regression] Use of redundant struct keyword in virtual function prototype combined with using statement causes compilation error

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60894

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

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

--- Comment #5 from Jason Merrill <jason at gcc dot gnu.org> ---
Any news?

[Bug c++/60894] [4.7/4.8/4.9/4.10 Regression] Use of redundant struct keyword in virtual function prototype combined with using statement causes compilation error

[fabien at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60894

--- Comment #6 from fabien at gcc dot gnu.org ---
(In reply to Jason Merrill from comment #5)
> Any news?

I looked into it but did not manage to get it fixed. I will have another try
this week. Thanks for the reminder.

[Bug c++/60894] [4.7/4.8/4.9/4.10 Regression] Use of redundant struct keyword in virtual function prototype combined with using statement causes compilation error

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60894

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.7.4                       |4.8.4

--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
The 4.7 branch is being closed, moving target milestone to 4.8.4.

[Bug c++/60894] [4.8/4.9/5 Regression] Use of redundant struct keyword in function prototype combined with using statement causes compilation error

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60894

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|4.10.0                      |5.0

--- Comment #8 from Jason Merrill <jason at gcc dot gnu.org> ---
(In reply to fabien from comment #6)
> I looked into it but did not manage to get it fixed. I will have another try
> this week. Thanks for the reminder.

Ping?

[Bug c++/60894] [4.8/4.9/5 Regression] Use of redundant struct keyword in function prototype combined with using statement causes compilation error

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60894

--- Comment #10 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Fabien?

[Bug c++/60894] [4.8/4.9/5 Regression] Use of redundant struct keyword in function prototype combined with using statement causes compilation error

[fabien at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60894

--- Comment #11 from fabien at gcc dot gnu.org ---
I posted a patch here:
https://gcc.gnu.org/ml/gcc-patches/2014-09/msg02190.html

[Bug c++/60894] [4.8/4.9/5 Regression] Use of redundant struct keyword in function prototype combined with using statement causes compilation error

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60894

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.8.4                       |4.8.5

--- Comment #12 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 4.8.4 has been released.

[Bug c++/60894] [4.8/4.9/5 Regression] Use of redundant struct keyword in function prototype combined with using statement causes compilation error

[paolo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60894

--- Comment #13 from paolo at gcc dot gnu.org <paolo at gcc dot gnu.org> ---
Author: paolo
Date: Fri Feb 13 23:57:10 2015
New Revision: 220702

URL: https://gcc.gnu.org/viewcvs?rev=220702&root=gcc&view=rev
Log:
/cp
2015-02-13  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/60894
    * decl.c (lookup_and_check_tag): Use strip_using_decl.

/testsuite
2015-02-13  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/60894
    * g++.dg/lookup/using54.C: New.

Added:
    trunk/gcc/testsuite/g++.dg/lookup/using54.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/decl.c
    trunk/gcc/testsuite/ChangeLog

[Bug c++/60894] [4.8/4.9 Regression] Use of redundant struct keyword in function prototype combined with using statement causes compilation error

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60894

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|fabien at gcc dot gnu.org          |paolo.carlini at oracle dot com
            Summary|[4.8/4.9/5 Regression] Use  |[4.8/4.9 Regression] Use of
                   |of redundant struct keyword |redundant struct keyword in
                   |in function prototype       |function prototype combined
                   |combined with using         |with using statement causes
                   |statement causes            |compilation error
                   |compilation error           |

--- Comment #14 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Fixed in mainline so far.

[Bug c++/60894] [4.8/4.9 Regression] Use of redundant struct keyword in function prototype combined with using statement causes compilation error

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60894

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.8.5                       |4.9.3

--- Comment #15 from Richard Biener <rguenth at gcc dot gnu.org> ---
The gcc-4_8-branch is being closed, re-targeting regressions to 4.9.3.

[Bug c++/60894] [4.9 Regression] Use of redundant struct keyword in function prototype combined with using statement causes compilation error

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60894

--- Comment #16 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 4.9.3 has been released.

[Bug c++/60894] [4.9 Regression] Use of redundant struct keyword in function prototype combined with using statement causes compilation error

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60894

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.9.3                       |4.9.4