[Bug c++/81947] New: variadic template specialization doesn't compile

[manish.baphna at citi dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81947

Bug ID: 81947
   Summary: variadic template specialization doesn't compile
   Product: gcc
   Version: 4.4.7
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c++
  Assignee: unassigned at gcc dot gnu.org
  Reporter: manish.baphna at citi dot com
  Target Milestone: ---

->cat vartemp.cpp & g++ vartemp.cpp -std=c++0x
template 
void send(const Type& ...args)
{
}

template <>
void send(const int&x, const double& y)
{
}

int main(){

}
vartemp.cpp:7: error: template-id âsend<>â for âvoid send(const int&, const
double&)â does not match any template declaration

gcc version 4.4.7 20120313

[Bug c++/81134] New: C++ partial template specialization issue

[manish.baphna at citi dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81134

Bug ID: 81134
   Summary: C++ partial template specialization issue
   Product: gcc
   Version: 6.1.0
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c++
  Assignee: unassigned at gcc dot gnu.org
  Reporter: manish.baphna at citi dot com
  Target Milestone: ---

Following code going into recursive template instantiation without realizing
terminating case. Works find with clang.

template   
struct GCD
{  
   static const int value = (N>M)? GCD::value : GCD::value;  
}; 
  
template  
struct GCD<0, M>{  
   static const int value = M;  
};  
template  
struct GCD
{
 static const int value = M ; 
};  
int main()  
{
static_assert(GCD<12,15>::value == 3, "Error");
} 

Error: g++ lcd.cpp -std=c++11
fatal error: template instantiation depth exceeds maximum of 900 (use
-ftemplate-depth= to increase the maximum)
  static const int value = (N>M)? GCD::value : GCD::value;

[Bug c++/81134] C++ partial template specialization issue

[manish.baphna at citi dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81134

--- Comment #2 from Manish  ---
Thanx Jonathan. 

Your explanation explains behavior. I wonder if standard has some preference
dictated here?

[Bug c++/81134] C++ partial template specialization issue

[manish.baphna at citi dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81134

--- Comment #4 from Manish  ---
Which section in particular you are referring?

I am looking at this doc, section 14.7 but couldn't find relevant point.
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3690.pdf

[Bug c++/81232] New: compiler crashes for template function overload

[manish.baphna at citi dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81232

Bug ID: 81232
   Summary: compiler crashes for template function overload
   Product: gcc
   Version: 6.1.0
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: c++
  Assignee: unassigned at gcc dot gnu.org
  Reporter: manish.baphna at citi dot com
  Target Milestone: ---

Created attachment 41636
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=41636&action=edit
diagnostic output from compiler

I am trying to use template function overloads and in a specific case, I was
expecting to deploy 'best match' overload but that somehow is not happening.
Template type deduction there is not matching 'best match' and compiler is
crashing(gcc6.1). Explicitly specifying types is helping here. Check main for
both versions of my usage. At this moment I am not sure if it's issue with gcc
or with my assumptions. Here is code

#include 
#include 

using namespace std;

template 
using int_ = integral_constant;

struct Meta
{
template static constexpr T ipow(T x)
{
return ipow(x, int_<(N < 0) ? -1 : N>());
}

template static constexpr T ipow(T x, int_<-1>)
{
return static_cast(1) / ipow<-N>(x, int_<-N>());
}

template static constexpr T ipow(T x, int_)
{
return x * ipow(x, int_());
}

template static constexpr T ipow(T x, int_<0>)
{
return 1;
}
};


int main(){
Meta m1;
cout << m1.ipow<-1, int>(2, int_<-1>()) << endl; // This works fine 
cout << m1.ipow(2, int_<-1>()) << endl;  // This crashes compiler
}