Pointer to array template parameter in partial specialization

[Oskar Enoksson]

The following template specialization construct is rejected by g++ 4.1.2
while icc 9.1 silently accepts is (even with -strict-ansi). Which
compiler is correct?



template<typename T>
struct x {};

template<typename T, unsigned N>
struct x<T*[N]> {};

int main() {
x<int> a;
x<int*[10]> b;
return 0;
}



bash> g++-4.1.2 -c tst.cpp
tst.cpp:7: error: template parameters not used in partial specialization:
tst.cpp:7: error: ‘T’

bash> icc -strict-ansi -o tst tstst.cpp
bash>


thanks
/Oskar

 

[Victor Bazarov]

The following template specialization construct is rejected by g++
4.1.2 while icc 9.1 silently accepts is (even with -strict-ansi).
Which compiler is correct?

I wanted to say that the code was fine, but went to check with Comeau
online, and it confirmed that -- the code is accepted.

template<typename T>
struct x {};

template<typename T, unsigned N>
struct x<T*[N]> {};

int main() {
x<int> a;
x<int*[10]> b;
return 0;
}



bash> g++-4.1.2 -c tst.cpp
tst.cpp:7: error: template parameters not used in partial
specialization: tst.cpp:7: error: ‘T’

bash> icc -strict-ansi -o tst tstst.cpp
bash>

V

 

[Gianni Mariani]

The following template specialization construct is rejected by g++ 4.1.2
while icc 9.1 silently accepts is (even with -strict-ansi). Which
compiler is correct?



template<typename T>
struct x {};

template<typename T, unsigned N>
struct x<T*[N]> {};

int main() {
x<int> a;
x<int*[10]> b;
return 0;
}



bash> g++-4.1.2 -c tst.cpp
tst.cpp:7: error: template parameters not used in partial specialization:
tst.cpp:7: error: ‘T’

Looks like a serious gcc bug to me.


Did you file it with the gcc people ?

 

[Victor Bazarov]

The following template specialization construct is rejected by g++
4.1.2 while icc 9.1 silently accepts is (even with -strict-ansi).
Which compiler is correct?



template<typename T>
struct x {};

template<typename T, unsigned N>
struct x<T*[N]> {};

int main() {
x<int> a;
x<int*[10]> b;
return 0;
}



bash> g++-4.1.2 -c tst.cpp
tst.cpp:7: error: template parameters not used in partial
specialization: tst.cpp:7: error: 'T'

Looks like a serious gcc bug to me.


Did you file it with the gcc people ?

Oh, and I just noticed (and read carefully) the subject of your
message, Oskar, and wanted to tell you that

T*[N]

is NOT a pointer to array, but rather an array of pointers to T.
A pointer to an array would be

T(*)[N]

V

 

[Gianni Mariani]

Victor Bazarov wrote:
....

is NOT a pointer to array, but rather an array of pointers to T.
A pointer to an array would be

T(*)[N]

gcc accepts that type parameter for X. It's still a bug for gcc however.

 

[Victor Bazarov]

Victor Bazarov wrote:
...

is NOT a pointer to array, but rather an array of pointers to T.
A pointer to an array would be

T(*)[N]

gcc accepts that type parameter for X. It's still a bug for gcc
however.

I wasn't arguing that it wasn't a bug...

V

 

[Oskar Enoksson]

The following template specialization construct is rejected by g++
4.1.2 while icc 9.1 silently accepts is (even with -strict-ansi).
Which compiler is correct?



template<typename T>
struct x {};

template<typename T, unsigned N>
struct x<T*[N]> {};

int main() {
x<int> a;
x<int*[10]> b;
return 0;
}



bash> g++-4.1.2 -c tst.cpp
tst.cpp:7: error: template parameters not used in partial
specialization: tst.cpp:7: error: 'T'

Looks like a serious gcc bug to me.


Did you file it with the gcc people ?

Oh, and I just noticed (and read carefully) the subject of your
message, Oskar, and wanted to tell you that

T*[N]

is NOT a pointer to array, but rather an array of pointers to T.
A pointer to an array would be

T(*)[N]

V

Yes ok thanks. This bug surprised me - it's a simple construct. I
thought g++ was pretty stable.

I've created a bug report on the gcc bugzilla site.

BTW Bugzilla crashed when creating the bug report, so I also reported a
bugzilla bug to the bugzilla maintainers in an email. If this email
bounces I give up. Am I just unlucky or is the free software
infrastructure deteriorating?

 

[Gianni Mariani]

Oskar Enoksson wrote:
....

BTW Bugzilla crashed when creating the bug report, so I also reported a
bugzilla bug to the bugzilla maintainers in an email. If this email
bounces I give up. Am I just unlucky or is the free software
infrastructure deteriorating?

This could be a regression in the gcc 4.X series. The gcc 3.4.4
compiler seems to work with this.

If it was a heavily used construct, it would have been fixed already.
However, I was a little surprised.

BTW - what's the bug ID ?

 

[Oskar Enoksson]

Oskar Enoksson wrote:
...

This could be a regression in the gcc 4.X series. The gcc 3.4.4
compiler seems to work with this.

If it was a heavily used construct, it would have been fixed already.
However, I was a little surprised.

BTW - what's the bug ID ?

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30924

/Oskar