[Bug c++/26148] New: g++ bug, possibly introduced around gcc 3.4.0

["gcc_bugzilla at friedman dot to" <gcc-bugzilla@gcc.gnu.org>]

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In the transcript below, the program "problem.C", which does not include any
header files, shows a bug in gcc 3.4.0 under Linux (kernel version 2.6.11)
running on an Intel Pentium 4, which still exists in gcc 4.0.2 but does not
exist in gcc 3.3.2.  I also enclose two slightly modified versions of
"problem.C", called "ok1.C" and "ok2.C", which both pass under the newer
compilers.

I have a very large software system in C++ which does not compile on the latest
compiler, and I spent a long time trying to reduce the code to this small
example which I enclose below in "problem.C".  Unfortunately, the two
workarounds "ok1.C" and "ok2.C" are not an option in my large system, and any
real workaround would involve either a significant design change or a major
kludge, both of which I would rather avoid, so until I hear from you I cannot
migrate my system over to the latest compiler.  Please help!

Sincerely,
Joseph Friedman, Ph.D.
Millennium Partners, L.P.
666 Fifth Avenue, 8th Floor
New York, NY 10103
(212) 841-4160

------------------------------------------------------------------------

% /usr/local/gcc-3.3.2/bin/g++ -v
Reading specs from
/usr/local/gcc-3.3.2/lib/gcc-lib/i686-pc-linux-gnu/3.3.2/specs
Configured with: ./configure --prefix=/usr/local/gcc-3.3.2
Thread model: posix
gcc version 3.3.2

% /usr/local/gcc-3.4.0/bin/g++ -v
Reading specs from
/apps/local.linux/gcc-3.4.0/bin/../lib/gcc/i686-pc-linux-gnu/3.4.0/specs
Configured with: ./configure --prefix=/usr/local/gcc-3.4.0
Thread model: posix
gcc version 3.4.0

% /usr/local/gcc-4.0.2/bin/g++ -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../configure --prefix=/usr/local/gcc-4.0.2
Thread model: posix
gcc version 4.0.2


% /usr/local/gcc-3.3.2/bin/g++ ok1.C
% /usr/local/gcc-3.3.2/bin/g++ ok2.C
% /usr/local/gcc-3.3.2/bin/g++ problem.C

% /usr/local/gcc-3.4.0/bin/g++ ok1.C
% /usr/local/gcc-3.4.0/bin/g++ ok2.C
% /usr/local/gcc-3.4.0/bin/g++ problem.C
problem.C: In constructor `s1<T>::s1(const T&) [with T = pair<double,
double>]':
problem.C:35:   instantiated from here
problem.C:14: error: cannot convert `const pair<double, double>' to `double'
for argument `1' to `void ns1::f(double)'

% /usr/local/gcc-4.0.2/bin/g++ ok1.C
% /usr/local/gcc-4.0.2/bin/g++ ok2.C
% /usr/local/gcc-4.0.2/bin/g++ problem.C
problem.C: In constructor ‘s1<T>::s1(const T&) [with T = pair<double,
double>]’:
problem.C:35:   instantiated from here
problem.C:14: error: cannot convert ‘const pair<double, double>’ to ‘double’
for argument ‘1’ to ‘void ns1::f(double)’

% cat problem.C
template<class T1, class T2>
struct pair { pair(T1 x, T2 y) : first(x) {} T1 first; T2 second; };
template<class T1, class T2>
pair<T1, T2> make_pair(T1 x, T2 y) { return pair<T1, T2>(x, y); }

namespace ns1 {
  void f(double x) {}
}

template<class T>
struct s1 {
    T a;
    int i;
    s1(const T& x) : a(x) { ns1::f(x); }
};

namespace ns1 {
  template<class T> bool f(const pair<T, T>& x) {
      f(x.first);
  }
}

template<class T>
struct s2 {
    typedef pair<T, T> pair_type;
};

template <class S>
struct s3 : public S {
    typedef s1<typename S::pair_type> t3;
};

int main() {
  pair<double, double> p = make_pair((double)5, (double)12);
  s3< s2<double> >::t3 o = s3< s2<double> >::t3(p);
  return 0;
}

% cat ok1.C
template<class T1, class T2>
struct pair { pair(T1 x, T2 y) : first(x) {} T1 first; T2 second; };
template<class T1, class T2>
pair<T1, T2> make_pair(T1 x, T2 y) { return pair<T1, T2>(x, y); }

namespace ns1 {
  void f(double x) {}
}

namespace ns1 {
  template<class T> bool f(const pair<T, T>& x) {
      f(x.first);
  }
}

template<class T>
struct s1 {
    T a;
    int i;
    s1(const T& x) : a(x) { ns1::f(x); }
};

template<class T>
struct s2 {
    typedef pair<T, T> pair_type;
};

template <class S>
struct s3 : public S {
    typedef s1<typename S::pair_type> t3;
};

int main() {
  pair<double, double> p = make_pair((double)5, (double)12);
  s3< s2<double> >::t3 o = s3< s2<double> >::t3(p);
  return 0;
}

% cat ok2.C
template<class T1, class T2>
struct pair { pair(T1 x, T2 y) : first(x) {} T1 first; T2 second; };
template<class T1, class T2>
pair<T1, T2> make_pair(T1 x, T2 y) { return pair<T1, T2>(x, y); }

void f(double x) {}

template<class T>
struct s1 {
    T a;
    int i;
    s1(const T& x) : a(x) { f(x); }
};

template<class T> bool f(const pair<T, T>& x) {
    f(x.first);
}

template<class T>
struct s2 {
    typedef pair<T, T> pair_type;
};

template <class S>
struct s3 : public S {
    typedef s1<typename S::pair_type> t3;
};

int main() {
  pair<double, double> p = make_pair((double)5, (double)12);
  s3< s2<double> >::t3 o = s3< s2<double> >::t3(p);
  return 0;
}


-- 
           Summary: g++ bug, possibly introduced around gcc 3.4.0
           Product: gcc
           Version: 4.0.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: gcc_bugzilla at friedman dot to


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26148