[Bug c++/53307] New: internal crash with variadic templates and decltype

[Bug c++/53307] New: internal crash with variadic templates and decltype

[chesstr at hotmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53307

             Bug #: 53307
           Summary: internal crash with variadic templates and decltype
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: chesstr@hotmail.com


Created attachment 27363
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27363
gcc_bug.cpp

Simplified code in the attachment gives below error :

gcc_bug.cpp:18:6: internal compiler error: Segmentation fault

[Bug c++/53307] internal crash with variadic templates and decltype

[chesstr at hotmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53307

chesstr at hotmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|major                       |normal

[Bug c++/53307] internal crash with variadic templates and decltype

[chesstr at hotmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53307

chesstr at hotmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  Attachment #27363|0                           |1
        is obsolete|                            |

--- Comment #1 from chesstr at hotmail dot com 2012-05-10 17:16:47 UTC ---
Created attachment 27366
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27366
better test case

It turns out, if the length of parameter pack arg3s... is 0 this bug occurs, if
it is not 0 then gcc compiles without any problem.

[Bug c++/53307] internal crash with variadic templates and decltype

[chesstr at hotmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53307

--- Comment #2 from chesstr at hotmail dot com 2012-05-10 20:09:44 UTC ---
Comment on attachment 27366
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27366
better test case

>#include <iostream>
>template<class...Ts> struct tuple{};
>
>struct funct{
>	template<class T,class...argTs>
>	T operator()(T arg1,argTs...args){
>		return arg1;
>	}
>};
>
>template<class...>class test;
>
>template< template <class...> class tp,
>	  class...arg1Ts,
>	  class...arg2Ts> 
>class test<tp<arg1Ts...>,tp<arg2Ts...>>{
>public:
>template<class func>
>auto test_pass(func fun,arg2Ts...arg2s) -> decltype(fun(arg2s...)) 
>{
>	int gcc_compiles_this;
>	int internal_gcc_crash=sizeof...(arg2s);
>	return fun(arg2s...);
>}
>template<class func,class...arg3Ts>
>auto testbug(func fun,arg2Ts...arg2s,arg3Ts...arg3s) -> decltype(fun(arg2s...,arg3s...)) 
>{
>	int clang_compiles_but_not_gcc;
>	int internal_gcc_crash=sizeof...(arg2s);
>	return fun(arg2s...,arg3s...);
>}
>};
>
>int main(){	
>	test<tuple<>,tuple<char,int>> t;
>	std::cout<<t.test_pass(funct(),'a',2);
>       std::cout<<t.testbug(funct(),'a',2,100.123);//works fine
>	//std::cout<<t.testbug(funct(),'a',2,"str");//fails <<<<<<<<<<<<<<<<<------------------------
>	std::cout<<"gcc crash : "<<t.testbug(funct(),'a',2);//fails <<<<<<<<<<<<<<<<<<<--------------
>}

[Bug c++/53307] internal crash with variadic templates and decltype

[chesstr at hotmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53307

--- Comment #3 from chesstr at hotmail dot com 2012-05-10 20:57:25 UTC ---
Therefore, it seems that 0 length argument packs are not handled correctly in
decltype.

[Bug c++/53307] internal crash with variadic templates and decltype

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53307

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|                            |4.7.2, 4.8.0

--- Comment #4 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-10-09 23:14:06 UTC ---
This is fixed in 4.7.2 and mainline. I'm adding the testcase.

[Bug c++/53307] internal crash with variadic templates and decltype

[paolo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53307

--- Comment #5 from paolo at gcc dot gnu.org <paolo at gcc dot gnu.org> 2012-10-09 23:37:12 UTC ---
Author: paolo
Date: Tue Oct  9 23:37:07 2012
New Revision: 192279

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=192279
Log:
2012-10-10  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/53307
    * g++.dg/cpp0x/decltype44.C: New.

Added:
    trunk/gcc/testsuite/g++.dg/cpp0x/decltype44.C
Modified:
    trunk/gcc/testsuite/ChangeLog

[Bug c++/53307] internal crash with variadic templates and decltype

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53307

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.7.2

--- Comment #6 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-10-09 23:40:12 UTC ---
Done.