[Bug c++/66153] New: Internal compiler error in nested template function

[Bug c++/66153] New: Internal compiler error in nested template function

[paboyle at ph dot ed.ac.uk]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66153

            Bug ID: 66153
           Summary: Internal compiler error in nested template function
           Product: gcc
           Version: 5.1.0
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: paboyle at ph dot ed.ac.uk
  Target Milestone: ---

Created attachment 35543
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35543&action=edit
Preprocessed source

Peters-MacBook-Pro:gcc5_debug pab$ g++-5 -std=c++11 broken.cc -o broken
'
Internal compiler error: Error reporting routines re-entered.

broken.cc: In substitution of 'template<int N, class obj> Container<decltype
(function<N>(arg.data[0]))> function(const Container<obj>&) [with int N = 1;
obj = <missing>]':
broken.cc:43:101:   recursively required by substitution of 'template<int N,
class obj> Container<decltype (function<N>(arg.data[0]))> function(const
Container<obj>&) [with int N = 1; obj = <missing>]'
broken.cc:43:101:   required by substitution of 'template<int N, class obj>
Container<decltype (function<N>(arg.data[0]))> function(const Container<obj>&)
[with int N = 1; obj = <missing>]'
broken.cc:45:33:   Abort trap: 6
 template<int N,class obj> auto function(const Container<obj> & arg)->
Container<decltype(function<N>(arg.data[0]))>
                                                                               
                     ^
g++-5: internal compiler error: Abort trap: 6 (program cc1plus)
Please submit a full bug report,
with preprocessed source if appropriate.
See <https://github.com/Homebrew/homebrew-versions/issues> for instructions.

==============
#include <vector>
#include <complex>
#include <type_traits>
#include <iostream>

typedef std::complex<double> ComplexD;

template <class T> class TypeMapper {
public:
  enum { NestLevel = T::NestLevel };
};

template<> class TypeMapper<ComplexD> {
public:
  enum { NestLevel = 0 };
};

template<class obj> class Container {
 public:
  std::vector<obj> data;
  Container(int size) : data (size){};
};

template<class obj> class Recursive {
public:
  enum { NestLevel = TypeMapper<obj>::NestLevel + 1};
  obj internal;
};

template<int N,class obj,typename std::enable_if<N==obj::NestLevel >::type * =
nullptr > auto function(const obj &arg)-> obj
{
  std::cout<<"Leaf "<<obj::NestLevel<<std::endl;
  return arg;
}
template<int N,class obj,typename std::enable_if<N!=obj::NestLevel >::type * =
nullptr > auto function(const obj &arg)-> obj
{
  std::cout<<"Node "<<obj::NestLevel<<std::endl;
  obj ret;
  ret.internal=function<N>(arg.internal);
  return ret;
}

template<int N,class obj> auto function(const Container<obj> & arg)->
Container<decltype(function<N>(arg.data[0]))>
{
  Container<decltype(function<N>(arg.data[0]))> ret(arg.data.size());
  for(int ss=0;ss<arg.data.size();ss++){
    ret.data[ss] = function<N>(arg.data[ss]);
  }
  return ret;
}


int main(int argc,char **argv)
{
  Container<Recursive<Recursive<ComplexD> > > array(10);
  Container<Recursive<Recursive<ComplexD> > > ret(10);

  ret = function<1>(array);
}
==============

For reference, works on Intel 15, Clang++ multiple versions.

Peters-MacBook-Pro:gcc5_debug pab$ icpc -std=c++11 broken.cc -o broken
Peters-MacBook-Pro:gcc5_debug pab$ clang++  -std=c++11 broken.cc -o broken
Peters-MacBook-Pro:gcc5_debug pab$ clang++ --version
Apple LLVM version 6.0 (clang-600.0.56) (based on LLVM 3.5svn)
Target: x86_64-apple-darwin14.1.0
Thread model: posix
Peters-MacBook-Pro:gcc5_debug pab$ icpc --version
icpc (ICC) 15.0.3 20150408
Copyright (C) 1985-2015 Intel Corporation.  All rights reserved.

Output with both icpc and clang++ is:

Peters-MacBook-Pro:gcc5_debug pab$ ./broken 
Node 2
Leaf 1
Node 2
Leaf 1
Node 2
Leaf 1
Node 2
Leaf 1
Node 2
Leaf 1
Node 2
Leaf 1
Node 2
Leaf 1
Node 2
Leaf 1
Node 2
Leaf 1
Node 2
Leaf 1

[Bug c++/66153] Internal compiler error in nested template function

[paboyle at ph dot ed.ac.uk]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66153

--- Comment #1 from Peter Boyle <paboyle at ph dot ed.ac.uk> ---
Created attachment 35547
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=35547&action=edit
unprocessed source code.

[Bug c++/66153] Internal compiler error in nested template function

[paboyle at ph dot ed.ac.uk]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66153

--- Comment #2 from Peter Boyle <paboyle at ph dot ed.ac.uk> ---
p.s. in case anyone is wondering this recursive construct is 
a simplification of a construct I'm using in an expression
template framework, so this is not simply a convoluted test case.

Rather, I distilled the fail down to a small case from a much larger code.

[Bug c++/66153] Internal compiler error in nested template function

[paboyle at ph dot ed.ac.uk]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66153

Peter Boyle <paboyle at ph dot ed.ac.uk> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|5.1.0                       |6.0

--- Comment #4 from Peter Boyle <paboyle at ph dot ed.ac.uk> ---
Also fails in HEAD

prog.cc:53:14: warning: unused parameter 'argc' [-Wunused-parameter]
 int main(int argc,char **argv)
              ^
prog.cc:53:26: warning: unused parameter 'argv' [-Wunused-parameter]
 int main(int argc,char **argv)
                          ^
'
Internal compiler error: Error reporting routines re-entered.
0x5ccf96 push_tinst_level_loc(tree_node*, unsigned int)
        /home/heads/gcc/gcc-source/gcc/cp/pt.c:8464
0x5e8409 push_tinst_level(tree_node*)
        /home/heads/gcc/gcc-source/gcc/cp/pt.c:8448
0x5e8409 fn_type_unification(tree_node*, tree_node*, tree_node*, tree_node*
const*, unsigned int, tree_node*, unification_kind_t, int, bool, bool)
        /home/heads/gcc/gcc-source/gcc/cp/pt.c:16238
0x5a5be9 add_template_candidate_real
        /home/heads/gcc/gcc-source/gcc/cp/call.c:3057
0x5a626c add_template_candidate
        /home/heads/gcc/gcc-source/gcc/cp/call.c:3154
0x5a626c add_candidates
        /home/heads/gcc/gcc-source/gcc/cp/call.c:5281
0x5a8843 perform_overload_resolution
        /home/heads/gcc/gcc-source/gcc/cp/call.c:3999
0x5a9d0a build_new_function_call(tree_node*, vec<tree_node*, va_gc,
vl_embed>**, bool, int)
        /home/heads/gcc/gcc-source/gcc/cp/call.c:4076
0x67114a finish_call_expr(tree_node*, vec<tree_node*, va_gc, vl_embed>**, bool,
bool, int)
        /home/heads/gcc/gcc-source/gcc/cp/semantics.c:2410
0x5d478d tsubst_copy_and_build(tree_node*, tree_node*, int, tree_node*, bool,
bool)
        /home/heads/gcc/gcc-source/gcc/cp/pt.c:15201
0x5d5308 tsubst(tree_node*, tree_node*, int, tree_node*)
        /home/heads/gcc/gcc-source/gcc/cp/pt.c:12512
0x60dd50 dump_template_bindings
        /home/heads/gcc/gcc-source/gcc/cp/error.c:369
0x60dd50 dump_substitution
        /home/heads/gcc/gcc-source/gcc/cp/error.c:1448
0x60f866 decl_to_string
        /home/heads/gcc/gcc-source/gcc/cp/error.c:2910
0x60f866 cp_printer
        /home/heads/gcc/gcc-source/gcc/cp/error.c:3491
0xfd6a10 pp_format(pretty_printer*, text_info*)
        /home/heads/gcc/gcc-source/gcc/pretty-print.c:613
0xfd7780 pp_format_verbatim(pretty_printer*, text_info*)
        /home/heads/gcc/gcc-source/gcc/pretty-print.c:672
0xfd7854 pp_verbatim(pretty_printer*, char const*, ...)
        /home/heads/gcc/gcc-source/gcc/pretty-print.c:873
0x609eda print_instantiation_partial_context_line
        /home/heads/gcc/gcc-source/gcc/cp/error.c:3290
0x609eda print_instantiation_partial_context
        /home/heads/gcc/gcc-source/gcc/cp/error.c:3400
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.

[Bug c++/66153] Internal compiler error in nested template function

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66153

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
           Severity|major                       |normal

[Bug c++/66153] Internal compiler error in nested template function

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66153

--- Comment #8 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Reduced further:
#include <type_traits>

template <class T> struct TypeMapper { static const int NestLevel =
T::NestLevel; };
template<> struct TypeMapper<double> { static const int NestLevel = 0; };
template<class obj> struct Container { obj data; };
template<class obj> struct Recursive {
  enum { NestLevel = TypeMapper<obj>::NestLevel + 1};
};
template<int N,class obj,  typename std::enable_if<N==obj::NestLevel >::type *
= nullptr >
auto function(const obj &arg)-> obj
{
  return arg;
}
template<int N,class obj, typename std::enable_if<N!=obj::NestLevel >::type * =
nullptr >
  auto function(const obj &arg)-> obj
{
  return obj{};
}
template<int N,class obj>
  auto function(const Container<obj> & arg) ->
Container<decltype(function<N>(arg.data))>
{
  Container<Recursive<Recursive<double> > > ret;
  return ret;
}
int main(int argc,char **argv)
{
  Container<Recursive<Recursive<double> > > array;
  Container<Recursive<Recursive<double> > > ret;

  function<1>(array);
}

----- CUT -----
I have seen another one similar to this recently.

[Bug c++/66153] Internal compiler error in nested template function

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66153

--- Comment #9 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Here is the full on reduced testcase (the previous one was wrong):
template<class obj> struct Container {
  obj data[1];
};
template<class obj> struct Recursive {};
template<int N,class obj> obj function(const obj &arg)
{
  return obj{};
}
template<int N,class obj>
  auto function(const Container<obj> & arg)
    -> Container<decltype(function<N>(arg.data[0]))>
{
  Container<decltype(function<N>(arg.data[0]))> ret;
  return ret;
}
int main(int argc,char **argv)
{
  Container<Recursive<Recursive<int> > > array;  
  function<1>(array);
}

[Bug c++/66153] Internal compiler error in nested template function

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66153

--- Comment #10 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
A little more reduced:
template<class obj> struct c { obj data; };
struct r {};
template<int N,class obj> obj g(const obj &arg);
template<int N,class obj>
  auto g(const c<obj> & arg)
    -> c<decltype(g<N>(arg.data))>
{
  return c<decltype(g<N>(arg.data))>{};
}
int main()
{
  c<r > array;  
  g<1>(array);
}
---- CUT ----
Without the guide for the return type, GCC accepts the code. Somehow GCC is
messing up g<N>, Removing the template argument N also allows GCC to accept the
code.