[Bug c++/53305] New: internal crash with variadic templates and decltype
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53305 Bug #: 53305 Summary: internal crash with variadic templates and decltype Classification: Unclassified Product: gcc Version: 4.6.3 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassig...@gcc.gnu.org ReportedBy: ches...@hotmail.com Created attachment 27362 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27362 simplified c++ code that crushes gcc g++ -std=c++0x gcc_bug.cpp -o t gcc_bug.cpp: In member function ‘int funct::operator()(argTs ...)’: gcc_bug.cpp:7:2: error: expected ‘;’ before ‘}’ token gcc_bug.cpp:23: confused by earlier errors, bailing out in the real (and more complex) code, instead the last error message was : internal compiler error: Segmentation fault
[Bug c++/53307] New: internal crash with variadic templates and decltype
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: unassig...@gcc.gnu.org ReportedBy: ches...@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
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
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chesstr at hotmail dot com changed: What|Removed |Added Attachment #27363|0 |1 is obsolete|| --- Comment #1 from chesstr at hotmail dot com 2012-05-10 17:16:47 UTC --- Created attachment 27366 --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
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
>template struct tuple{};
>
>struct funct{
> template
> T operator()(T arg1,argTs...args){
> return arg1;
> }
>};
>
>templateclass test;
>
>template< template class tp,
> class...arg1Ts,
> class...arg2Ts>
>class test,tp>{
>public:
>template
>auto test_pass(func fun,arg2Ts...arg2s) -> decltype(fun(arg2s...))
>{
> int gcc_compiles_this;
> int internal_gcc_crash=sizeof...(arg2s);
> return fun(arg2s...);
>}
>template
>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> t;
> std::cout< std::cout< //std::cout< <<<<<<<<<<<<<<<<<
> std::cout<<"gcc crash : "< <<<<<<<<<<<<<<<<<<<--
>}
[Bug c++/53307] internal crash with variadic templates and decltype
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++/53311] New: [C++0x] argument packs are not handled correctly in decltype
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53311
Bug #: 53311
Summary: [C++0x] argument packs are not handled correctly in
decltype
Classification: Unclassified
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: ches...@hotmail.com
Created attachment 27368
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27368
test case with both errors
Hi, it seems there are two major argument pack expansion problems in decltype :
1. mismatched argument pack lengths while expanding std::forward(args)...
from sample code :
=
> template
> auto testbug1(func fun,arg2Ts...arg2s,arg3Ts...arg3s) ->
> decltype(fun(std::forward(arg2s)...,std::forward(arg3s)...))
> {
> return
> fun(std::forward(arg2s)...,std::forward(arg3s)...);
> }
=
2. 0 length argument packs in decltype result in ICE
( Bug 53307 : http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53307 )
[Bug c++/53311] [C++0x] argument packs are not handled correctly in decltype
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53311 chesstr at hotmail dot com changed: What|Removed |Added Attachment #27368|0 |1 is obsolete|| --- Comment #1 from chesstr at hotmail dot com 2012-05-11 12:36:12 UTC --- Created attachment 27371 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27371 simpler test case Tested and simplified.Uncomment the problematic lines to see the bugs.
[Bug c++/53648] New: nested empty tuple
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53648
Bug #: 53648
Summary: nested empty tuple
Classification: Unclassified
Product: gcc
Version: 4.8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: ches...@hotmail.com
#include
int main(){
auto b = std::tuple>>{};
}
gives :
error: 'std::_Tuple_impl<1ul>' is an ambiguous base of 'std::_Tuple_impl<0ul,
std::tuple > >'
[Bug libstdc++/53648] [C++11] nested empty tuples
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53648 --- Comment #2 from chesstr at hotmail dot com 2012-06-12 17:13:33 UTC --- (In reply to comment #1) > I have a fix for this already, IIRC it's simply a case of not using the EBO > for > a tuple that contains std::tuple<> Yes, an easy fix in tuple implementation by modifying __empty_not_final as below compiles : template using __empty_not_final = typename conditional<__is_final(_Tp)||is_same<_Tp,tuple<>>::value, false_type, is_empty<_Tp>>::type; instead of template using __empty_not_final = typename conditional<__is_final(_Tp), false_type, is_empty<_Tp>>::type;
[Bug libstdc++/53648] [C++11] nested empty tuples
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53648
--- Comment #4 from chesstr at hotmail dot com 2012-06-12 18:03:56 UTC ---
(In reply to comment #3)
> There are other cases involving non-empty tuples that will still result in an
> ambiguity e.g.
>
> struct A { };
> auto d = tuple, A>, A>{};
>
> My solution avoids using the EBO for some condition I don't remember (the
> code's on another machine) but it handles all the cases I tested.
>
> I also preserve the property that sizeof(tuple>)==1, which I
> think your suggestion loses.
You are right, the suggestion does not solve the real problem at all. Nice
example.
