c++/2127: namespace problems

[reichelt at igpm dot rwth-aachen dot de]

>Number:         2127
>Category:       c++
>Synopsis:       namespace problems
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Wed Feb 28 12:16:00 PST 2001
>Closed-Date:
>Last-Modified:
>Originator:     Volker Reichelt
>Release:        gcc version 3.0 20010227 (prerelease)
>Organization:
>Environment:
mips-sgi-irix6.5
>Description:
Compiling the following lines of code

namespace XXX {

struct S1 { int i; };
struct S2 { int i; };

bool operator == ( const S1&, const S1& ) { return true; }

template <class T> bool dummy ( const T &x ) { return x==x; }

}

bool operator == ( const XXX::S2&, const XXX::S2& ) { return true; }

void f () { XXX::S2 A; XXX::dummy(A); }


I get the error message

NamespaceBug.cpp: In function `bool XXX::dummy(const T&) [with T = XXX::S2]':
NamespaceBug.cpp:14:   instantiated from here
NamespaceBug.cpp:8: no match for `const XXX::S2& == const XXX::S2&' operator
NamespaceBug.cpp:6: candidates are: bool XXX::operator==(const XXX::S1&, const XXX::S1&)

Obviously the compiler fails to find the second operator ==.
Without namespaces or if one leaves out the first operator ==
everything works fine.
(gcc 2.95 shows the same behaviour, so this is not really a
regression. But because gcc 2.95 isn't so picky about the
namespace std, the code worked at least for XXX=std, whereas
gcc 3.0 fails for any namespace name.)
>How-To-Repeat:
g++ -c NamespaceBug.cpp
(assuming the file is named 'NamespaceBug.cpp')
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: