[Bug c++/33553] New: Bogus "array bound is not an integer constant" for parameter in template method of template class

[e dot tadeu at gmail dot com]

X-Bugzilla-Reason: CC

This error happens in this case:

template <class T_> class SizeFor_{ public: enum {Size = 2}; };

template <class V_>
class Test {
public:
    template <class T_>
    void test_array(T_ tag, V_ (&arr)[SizeFor_<T_>::Size])
    {
    }
};

(Full test case in the end of the message)

It happens when declaring an array, whose bounds is given by a static constant,
in a template method that is inside a template method.

The problem also happens when the static constant is a sizeof, or a static
const size_t.


Test case:

class X {};
class Y {};
class Z {};

//template <class T_> class SizeFor_;
//template<> class SizeFor_<X> { public: enum {Size = 1}; };
//template<> class SizeFor_<Y> { public: enum {Size = 2}; };
//template<> class SizeFor_<Z> { public: enum {Size = 3}; };

template <class T_> class SizeFor_ { public: enum {Size = 2}; };


// This works (template method of non-template class)
/*
class Test {
public:
    template <class T_>
    void test_array(T_, int (&arr)[SizeFor_<T_>::Size])
    {
        for (int i = 0; i < SizeFor_<T_>::Size; ++i) {
            arr[i] += 1;
        }
    }
};

int main() {
    int y[2] = {2, 3};

    Test p2;
    p2.test_array(Y(), y);

    return 0;
}
*/




// This works: (non-template method of template clas)
/*
template <class V_>
class Test {
public:
    void test_array(Y tag, V_ (&arr)[SizeFor_<Y>::Size])
    {
        for (int i = 0; i < SizeFor_<Y>::Size; ++i) {
            arr[i] += 1;
        }
    }
};

int main() {
    int y[2] = {2, 3};

    Test<int> p2;
    p2.test_array(Y(), y);

    return 0;
}
*/



// This one does not compile (template method of template class):

template <class V_>
class Test {
public:
    template <class T_>
    void test_array(T_ tag, V_ (&arr)[SizeFor_<T_>::Size])
    {
        for (int i = 0; i < SizeFor_<T_>::Size; ++i) {
            arr[i] += 1;
        }
    }
};

int main() {
    int y[2] = {2, 3};

    Test<int> p2;
    p2.test_array(Y(), y);

    return 0;
}



The compiler output is:

Using built-in specs.
Target: x86_64-unknown-linux-gnu
Configured with: ../Sources/configure
--with-ld=/home/users/ama/Shared/amd64.redhat/binutils-2.17/bin/ld
--disable-multilib
--prefix=/home/users/ama/Build/gcc-4.2.1/Binaries-amd64.redhat : (reconfigured)
../Sources/configure
--with-ld=/home/users/ama/Shared/amd64.redhat/binutils-2.17/bin/ld
--disable-multilib
--prefix=/home/users/ama/Build/gcc-4.2.1/Binaries-amd64.redhat
Thread model: posix
gcc version 4.2.1
...
cc1plus -fpreprocessed test3.ii -quiet -dumpbase test3.cpp -mtune=generic
-auxbase test3 -version -o test3.s
GNU C++ version 4.2.1 (x86_64-unknown-linux-gnu)
        compiled by GNU C version 4.2.1.
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: b0e2ae18bf4812f9f66b45414d2388db
test3.cpp: In instantiation of 'Test<int>':
test3.cpp:81:   instantiated from here
test3.cpp:70: error: array bound is not an integer constant
test3.cpp: In function 'int main()':
test3.cpp:82: error: 'class Test<int>' has no member named 'test_array'


-- 
           Summary: Bogus "array bound is not an integer constant" for
                    parameter in template method of template class
           Product: gcc
           Version: 4.2.1
            Status: UNCONFIRMED
          Severity: critical
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: e dot tadeu at gmail dot com
 GCC build triplet: x86_64-unknown-linux-gnu
  GCC host triplet: x86_64-unknown-linux-gnu
GCC target triplet: x86_64-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33553