c++/6331: g++ 3.1 looses const qualifiers

[pthomas at suse dot de]

>Number:         6331
>Category:       c++
>Synopsis:       g++ 3.1 looses const qualifiers
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Wed Apr 17 02:46:00 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     Philipp Thomas, SuSE Linux Ag
>Release:        3.1
>Organization:
>Environment:
suse-linux-gnu
>Description:
Gcc rejects the attached code, stating that the conversion is illegal. Output of 'c++ -v -c gcc31_bug_const.cc' is:

Using built-in specs.
Configured with: ../configure --enable-threads=posix --prefix=/usr --with-local-prefix=/usr/local --infodir=/usr/share/info --mandir=/usr/share/man --enable-languages=c,c++,f77,objc,java,ada --with-gxx-include-dir=/usr/include/g++ --with-slibdir=/lib --with-system-zlib --enable-shared i486-suse-linux
Thread model: posix
gcc version 3.1 20020408 (prerelease)
 /usr/lib/gcc-lib/i486-suse-linux/3.1/cc1plus -v -D__GNUC__=3 -D__GNUC_MINOR__=1 -D__GNUC_PATCHLEVEL__=0 -D__ELF__ -Dunix -Dlinux -D__ELF__ -D__unix__ -D__linux__ -D__unix -D__linux -Asystem=posix -D__NO_INLINE__ -D__STDC_HOSTED__=1 -D_GNU_SOURCE -Acpu=i386 -Amachine=i386 -Di386 -D__i386 -D__i386__ -D__tune_i486__ gcc31_bug_const.cc -D__GNUG__=3 -D__DEPRECATED -D__EXCEPTIONS -D__GXX_ABI_VERSION=100 -quiet -dumpbase gcc31_bug_const.cc -version -fmessage-length=0 -o /tmp/ccVQg0M0.s
GNU CPP version 3.1 20020408 (prerelease) (cpplib) (i386 Linux/ELF)
GNU C++ version 3.1 20020408 (prerelease) (i486-suse-linux)
        compiled by GNU C version 3.1 20020408 (prerelease).
ignoring nonexistent directory "/usr/i486-suse-linux/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/include/g++
 /usr/include/g++/i486-suse-linux
 /usr/include/g++/backward
 /usr/local/include
 /usr/lib/gcc-lib/i486-suse-linux/3.1/include
 /usr/include
End of search list.
gcc31_bug_const.cc: In member function `int Collision::automatic_shift()':
gcc31_bug_const.cc:38: invalid conversion from `int (*)(int* const&, int* const&)' to `int (*)(int*&, int*&)'
gcc31_bug_const.cc:38:   initializing argument 1 of `void Link_array<T>::sort(int (*)(T*&, T*&), int, int) [with T = int]'
gcc31_bug_const.cc: In member function `void Link_array<T>::sort(int (*)(T*&, T*&), int, int) [with T = int]':
gcc31_bug_const.cc:38:   instantiated from here
gcc31_bug_const.cc:29: invalid conversion from `int (*)(int* const&, int* const&)' to `int (*)(int*&, int*&)'
gcc31_bug_const.cc:29:   initializing argument 1 of `void Link_array<T>::sort(int (*)(T*&, T*&), int, int) [with T = int]'
>How-To-Repeat:

>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
----gnatsweb-attachment----
Content-Type: text/plain; name="gcc31_bug_const.cc"
Content-Disposition: inline; filename="gcc31_bug_const.cc"

template<class T>
class Link_array
{
public:
  Link_array () {}
  Link_array (Link_array<T> const &src) {}
  // quicksort.
  void sort (int (*compare) (T *const&,T *const&),
	     int lower = -1, int upper = -1);
};

class Note_column
{
public:
  static int shift_compare (int *const &, int *const &) {};
};

class Collision			// interface
{
public:
  int automatic_shift ();
};

template<class T> void
Link_array<T>::sort (int (*compare) (T *const&,T *const&),
		int lower, int upper) 
{
  int last = lower;
  sort (compare, lower, last-1);
}

int
Collision::automatic_shift ()
{
  int d = 1;
  Link_array<int> clashes;

  clashes.sort (Note_column::shift_compare);
  return 1;
}

int main()
{
  return 0;
}