[Bug c++/53821] New: [4.7.2,4.8 regression][c++11] multiple definitions of lambda

[Bug c++/53821] New: [4.7.2,4.8 regression][c++11] multiple definitions of lambda

[vincenzo.innocente at cern dot ch]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53821

             Bug #: 53821
           Summary: [4.7.2,4.8 regression][c++11] multiple definitions of
                    lambda
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: vincenzo.innocente@cern.ch


this is a regression as not happening in 4.6.2 and 4.7.1
I personally think that the template methods SHOULD be declared inline if
included in multiple sources…

anyhow since it was discussed at length  in PR53780 and PR53768
and got attention from developers I promised to reduce and post

cat inlT.cc
#include <algorithm>
template<typename T> struct Foo {

   virtual int bar(int,int);
   int k;
};

// int ebar(int,int) __attribute__ ((visibility ("default")));


template<typename T> 
int Foo<T>::bar(int i, int j) {
  auto ebar = [](int a, int b) { return a+b;};
  static int a=i;
  if (i>0) k = ebar(i,j);
  if (j>0) k = ebar(j,i);
  if (i>0) k = ebar(j,i);
  if (k>0) k = ebar(i,j);
  return (a==i) ? i : j;
}


struct A1 {

  Foo<float> * foo;

};


int __attribute__ ((visibility ("default")))  hello1 (int i, int j) { A1 a;
return a.foo->bar(i,j);} 

[vocms123] ~/public/ctest/bugs48 $ cat inlT2.cc
#include <algorithm>
template<typename T> struct Foo {

   virtual int bar(int,int);
   int k;
};

// int ebar(int,int) __attribute__ ((visibility ("default")));


template<typename T> 
int Foo<T>::bar(int i, int j) {
  auto ebar = [](int a, int b) { return a+b;};
  static int a=i;
  if (i>0) k = ebar(i,j);
  if (j>0) k = ebar(j,i);
  if (i>0) k = ebar(j,i);
  if (k>0) k = ebar(i,j);
  return (a==i) ? i : j;
}


struct A2 {

  Foo<float> * foo;

};

int __attribute__ ((visibility ("default")))  hello2 (int i, int j) { A2 a;
return a.foo->bar(i,j);} 


[vocms123] ~/public/ctest/bugs48 $ cat buildInlT
c++ -std=gnu++11 -O2 -fvisibility-inlines-hidden -fvisibility=hidden -flto -c
inlT.cc  -fPIC
c++ -std=gnu++11 -O2 -fvisibility-inlines-hidden -fvisibility=hidden -flto -c
inlT2.cc -fPIC
c++ -std=gnu++11 -O2 -fvisibility-inlines-hidden -fvisibility=hidden -flto
-shared inlT.o inlT2.o -fPIC -o inlT.so

source buildInlT
/afs/cern.ch/user/i/innocent/w3/gcc47slc5/bin/ld: error: inlT2.o: multiple
definition of 'Foo<float>::bar(int, int)::{lambda(int, int)#1}::_FUN(int, int)'
/afs/cern.ch/user/i/innocent/w3/gcc47slc5/bin/ld: inlT.o: previous definition
here
/afs/cern.ch/user/i/innocent/w3/gcc47slc5/bin/ld: error: inlT2.o: multiple
definition of 'Foo<float>::bar(int, int)::{lambda(int, int)#1}::operator int
(*)(int, int)() const'
/afs/cern.ch/user/i/innocent/w3/gcc47slc5/bin/ld: inlT.o: previous definition
here
collect2: error: ld returned 1 exit status

also with simpler
cat buildInlT0
c++ -std=gnu++11 -O2    -c inlT.cc  -fPIC
c++ -std=gnu++11 -O2    -c inlT2.cc -fPIC
c++ -std=gnu++11 -O2    -shared inlT.o inlT2.o -fPIC -o inlT.so
 source buildInlT0
/afs/cern.ch/user/i/innocent/w3/gcc47slc5/bin/ld: error: inlT2.o: multiple
definition of 'Foo<float>::bar(int, int)::{lambda(int, int)#1}::_FUN(int, int)'
/afs/cern.ch/user/i/innocent/w3/gcc47slc5/bin/ld: inlT.o: previous definition
here
/afs/cern.ch/user/i/innocent/w3/gcc47slc5/bin/ld: error: inlT2.o: multiple
definition of 'Foo<float>::bar(int, int)::{lambda(int, int)#1}::operator int
(*)(int, int)() const'
/afs/cern.ch/user/i/innocent/w3/gcc47slc5/bin/ld: inlT.o: previous definition
here


c++ -v
Using built-in specs.
COLLECT_GCC=c++
COLLECT_LTO_WRAPPER=/afs/cern.ch/user/i/innocent/w3/gcc47slc5/libexec/gcc/x86_64-unknown-linux-gnu/4.7.2/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-4.7/configure --enable-languages=c,c++,fortran
--disable-multilib --enable-gold=yes --disable-nls --enable-lto
--with-mpc=/afs/cern.ch/cms/slc5_amd64_gcc470/external/gcc/4.7.0
--with-gmp=/afs/cern.ch/cms/slc5_amd64_gcc470/external/gcc/4.7.0
--with-mpfr=/afs/cern.ch/cms/slc5_amd64_gcc470/external/gcc/4.7.0
--prefix=/afs/cern.ch/user/i/innocent/w3/gcc47slc5
--with-build-time-tools=/build/ge/new-binutils/a/slc5_amd64_gcc470/external/gcc/4.7.0-cms/bin
Thread model: posix
gcc version 4.7.2 20120629 (prerelease) [gcc-4_7-branch revision 189081] (GCC) 
[vocms123] ~/public/ctest/bugs48 $ ld -v
GNU gold (GNU Binutils 2.22.52.20120515) 1.11

[Bug c++/53821] [4.7.2,4.8 regression][c++11] multiple definitions of lambda

[vincenzo.innocente at cern dot ch]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53821

--- Comment #1 from vincenzo Innocente <vincenzo.innocente at cern dot ch> 2012-06-30 15:33:15 UTC ---
to clarify: 
in compiles and links correctly provided that
template<typename T> 
inline
int Foo<T>::bar(int i, int j)

or if instead of the lambda "bar" invokes the external "ebar"

[Bug c++/53821] [4.7.2,4.8 regression][c++11] multiple definitions of lambda

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53821

H.J. Lu <hjl.tools at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2012-06-30
                 CC|                            |jason at redhat dot com
   Target Milestone|---                         |4.7.2
     Ever Confirmed|0                           |1

--- Comment #2 from H.J. Lu <hjl.tools at gmail dot com> 2012-06-30 19:22:16 UTC ---
It is caused by revision 188117:

http://gcc.gnu.org/ml/gcc-cvs/2012-06/msg00027.html

[Bug c++/53821] [4.7/4.8 regression][c++11] multiple definitions of lambda

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53821

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1
      Known to work|                            |4.7.1
            Summary|[4.7.2,4.8                  |[4.7/4.8 regression][c++11]
                   |regression][c++11] multiple |multiple definitions of
                   |definitions of lambda       |lambda

[Bug c++/53821] [4.7/4.8 regression][c++11] multiple definitions of lambda

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53821

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-07-02 10:07:17 UTC ---
This is PR 53675

[Bug c++/53821] [4.7/4.8 regression][c++11] multiple definitions of lambda

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53821

--- Comment #4 from Jason Merrill <jason at gcc dot gnu.org> 2012-07-02 19:14:40 UTC ---
Author: jason
Date: Mon Jul  2 19:14:34 2012
New Revision: 189175

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=189175
Log:
    PR c++/53821
    * semantics.c (maybe_add_lambda_conv_op): Don't set
    DECL_INTERFACE_KNOWN.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-template6.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/semantics.c
    trunk/gcc/testsuite/ChangeLog

--- Comment #5 from Jason Merrill <jason at gcc dot gnu.org> 2012-07-02 19:15:03 UTC ---
Author: jason
Date: Mon Jul  2 19:14:58 2012
New Revision: 189176

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=189176
Log:
    PR c++/53821
    * semantics.c (maybe_add_lambda_conv_op): Don't set
    DECL_INTERFACE_KNOWN.

Added:
   
branches/gcc-4_7-branch/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-template6.C
Modified:
    branches/gcc-4_7-branch/gcc/cp/ChangeLog
    branches/gcc-4_7-branch/gcc/cp/semantics.c
    branches/gcc-4_7-branch/gcc/testsuite/ChangeLog

[Bug c++/53821] [4.7/4.8 regression][c++11] multiple definitions of lambda

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53821

--- Comment #4 from Jason Merrill <jason at gcc dot gnu.org> 2012-07-02 19:14:40 UTC ---
Author: jason
Date: Mon Jul  2 19:14:34 2012
New Revision: 189175

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=189175
Log:
    PR c++/53821
    * semantics.c (maybe_add_lambda_conv_op): Don't set
    DECL_INTERFACE_KNOWN.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-template6.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/semantics.c
    trunk/gcc/testsuite/ChangeLog

[Bug c++/53821] [4.7/4.8 regression][c++11] multiple definitions of lambda

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53821

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |jason at gcc dot gnu.org
         Resolution|                            |FIXED

--- Comment #6 from Jason Merrill <jason at gcc dot gnu.org> 2012-07-02 19:25:28 UTC ---
Fixed.

[Bug c++/53821] [4.7/4.8 regression][c++11] multiple definitions of lambda

[vincenzo.innocente at cern dot ch]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53821

--- Comment #7 from vincenzo Innocente <vincenzo.innocente at cern dot ch> 2012-07-03 20:39:50 UTC ---
I'm still wandering, more in general, if there is a semantic difference between


template<typename T> 
int Foo<T>::bar(int i, int j) {
…
}

and

template<typename T> 
inline
int Foo<T>::bar(int i, int j) {
…
}

[Bug c++/53821] [4.7/4.8 regression][c++11] multiple definitions of lambda

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53821

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

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

--- Comment #8 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-07-03 20:55:25 UTC ---
*** Bug 53675 has been marked as a duplicate of this bug. ***

[Bug c++/53821] [4.7/4.8 regression][c++11] multiple definitions of lambda

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53821

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|jason at redhat dot com     |

--- Comment #9 from Jason Merrill <jason at gcc dot gnu.org> 2012-07-03 21:28:02 UTC ---
The only difference is the hint to the compiler that you want the function to
be inlined.

[Bug c++/53821] [4.7/4.8 regression][c++11] multiple definitions of lambda

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53821

--- Comment #10 from Jason Merrill <jason at gcc dot gnu.org> 2012-12-06 14:37:25 UTC ---
Author: jason
Date: Thu Dec  6 14:37:13 2012
New Revision: 194251

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=194251
Log:
    PR c++/55015
    PR c++/53821
    * semantics.c (maybe_add_lambda_conv_op): Revert earlier change.
    * decl.c (start_preparsed_function): Make local class methods comdat
    in templates, too.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-conv6.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/decl.c
    trunk/gcc/cp/semantics.c

[Bug c++/53821] [4.7/4.8 regression][c++11] multiple definitions of lambda

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53821

--- Comment #11 from Jason Merrill <jason at gcc dot gnu.org> 2012-12-06 14:39:58 UTC ---
Author: jason
Date: Thu Dec  6 14:39:52 2012
New Revision: 194253

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=194253
Log:
    PR c++/55015
    PR c++/53821
    * semantics.c (maybe_add_lambda_conv_op): Revert earlier change.
    * decl.c (start_preparsed_function): Make local class methods comdat
    in templates, too.

Added:
    branches/gcc-4_7-branch/gcc/testsuite/g++.dg/cpp0x/lambda/lambda-conv6.C
Modified:
    branches/gcc-4_7-branch/gcc/cp/ChangeLog
    branches/gcc-4_7-branch/gcc/cp/decl.c
    branches/gcc-4_7-branch/gcc/cp/semantics.c