CODEWITHSUNDEEP
c++visual-studio-2015
Andreas Fabri
Andreas Fabri

Reputation: 1235

Is this a known VC14 bug

The code below gives me a compilation error.

$ cl.exe VC14-bug.cpp

Microsoft (R) C/C++ Optimizing Compiler Version 19.00.23026 for x64

Copyright (C) Microsoft Corporation. All rights reserved.

VC14-bug.cpp

VC14-bug.cpp(41): error C2893: Failed to specialize function template 'void fails(T1,Poly> *)'

VC14-bug.cpp(41): note: With the following template arguments:

VC14-bug.cpp(41): note: 'T1=int'

VC14-bug.cpp(41): note: 'T2=Kernel'

It is the function f() which poses a problem. Can anybody reproduce it? 

template <typename T>
struct Container
{};


struct Kernel {
typedef int Nested;
};


template <class K,
          class C = Container<typename K::Nested*> >
struct Poly
{};


// if f() gets commented it compiles
template<class T>
Poly<T>* 
f()
{ 
    return 0;
}


//template<class T2, class T1> // this compiles
template<class T1, class T2>
void
fails(T1, 
      Poly<T2> *)
{}


// if f() is moved here it also compiles

int main()
{  
    Poly<Kernel> * poly = 0;

    fails(0, poly);

    return 0;
}

Upvotes: 0

Views: 340

Answers (1)

lrineau
lrineau

Reputation: 6294

That is certainly a bug in the template parameters deduction code of VC14.

One possible workaround is to allow all types of containers for Poly, in fails:

template<class T1, class T2, class Cont>
void
fails(T1, 
      Poly<T2, Cont> *)
{}

I have verified using online Visual C++ compiler. Unfortunately, one cannot link to test cases like what we would do on Ideone.com (click to see the compilation with g++-5.1).

Upvotes: 1

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