[Bug c++/32505] New: Partial specialization halfway accepted after instantiation

["dascandy at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

The following code produces predictable but odd output. The compiler should
either generate a warning for this case or throw away the instantiation of the
type upon encountering the better-matching partial specialization, somehow
keeping it for code above the given line.


template <typename T>
struct A {
        T o;
};

int sizeofa = sizeof(A<int *>);

template <typename T>
struct A<T *> {
        T o[5];
};

int newsizeofa = sizeof(A<int *>);

int main() {
        printf("%d, %d, %d\n", sizeofa, sizeof(A<int *>), sizeof(A<double *>));
}


The given output is 4, 4, 40, whereas the expected output would be 4, 20, 40.
It appears that the specialization is accepted for any type not yet
instantiated.


Configured with: ../gcc-4.1.2/configure --prefix=/usr --enable-shared
--enable-languages=ada,c,c++,fortran,java,objc --enable-threads=posix
--enable-__cxa_atexit --disable-checking --with-gnu-ld --verbose
--with-arch=i486 --target=i486-slackware-linux --host=i486-slackware-linux
gcc version 4.1.2


-- 
           Summary: Partial specialization halfway accepted after
                    instantiation
           Product: gcc
           Version: 4.1.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: dascandy at gmail dot com
 GCC build triplet: i486-slackware-linux
  GCC host triplet: i486-slackware-linux
GCC target triplet: i486-slackware-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32505