[Bug c++/18195] New: Two-stage lookup doesn't work correctly with namespaces

[schepler at math dot berkeley dot edu]

With the following test program, I get compiler errors with g++-3.4 on both 
i386-linux and x86_64-linux (but not with g++-3.3). 
 
namespace A { 
  class B { }; 
 
  B* transform(B*); 
 
  template <class T> void transform_in_place(T*& p) { p = A::transform(p); } 
 
  class C { }; 
 
  C* transform(C*); 
}; 
 
namespace A { 
  class D { }; 
 
  D* transform(D*); 
}; 
 
void foo() { 
  A::B *b; 
  A::C *c; 
  A::D *d; 
 
  A::transform_in_place(b); 
  A::transform_in_place(c); 
  A::transform_in_place(d); 
} 
 
The exact error messages are: 
 
ns2.cpp: In function `void A::transform_in_place(T*&) [with T = A::C]': 
ns2.cpp:25:   instantiated from here 
ns2.cpp:6: error: cannot convert `A::C*' to `A::B*' for argument `1' to `A::B* 
A::transform(A::B*)' 
ns2.cpp: In function `void A::transform_in_place(T*&) [with T = A::D]': 
ns2.cpp:26:   instantiated from here 
ns2.cpp:6: error: cannot convert `A::D*' to `A::B*' for argument `1' to `A::B* 
A::transform(A::B*)' 
 
If I remove the namespace A everywhere, then this file compiles without 
errors.  According to my understanding of the section "Name lookup" under "C++ 
Misunderstandings" in the info file, this code should be correct since the 
call to transform depends on a template parameter, so the lookup should happen 
at instantiation time. 
 
(This is a condensed case of problems I'm getting with various versions of 
gtk--, after correcting other things.) 
 
g++ -v shows: 
Reading specs from /usr/lib/gcc/x86_64-linux/3.4.2/specs 
Configured with: ../src/configure -v 
--enable-languages=c,c++,java,f77,pascal,objc,treelang --prefix=/usr 
--libexecdir=/usr/lib --with-gxx-include-dir=/usr/include/c++/3.4 
--enable-shared --with-system-zlib --enable-nls --without-included-gettext 
--program-suffix=-3.4 --enable-__cxa_atexit --enable-libstdcxx-allocator=mt 
--enable-clocale=gnu --enable-libstdcxx-debug --enable-java-gc=boehm 
--enable-java-awt=gtk --disable-werror x86_64-linux 
Thread model: posix 
gcc version 3.4.2 (Debian 3.4.2-3)

-- 
           Summary: Two-stage lookup doesn't work correctly with namespaces
           Product: gcc
           Version: 3.4.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: schepler at math dot berkeley dot edu
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18195