c++/3048: Lookup problem (gcc 2.95 regression)

[Peter Schmid <schmid at snake dot iap dot physik dot tu-darmstadt dot de>]

>Number:         3048
>Category:       c++
>Synopsis:       Lookup problem (gcc 2.95 regression)
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Mon Jun 04 11:56:00 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Peter Schmid
>Release:        3.0 20010604 (prerelease)
>Organization:
TU Darmstadt
>Environment:
System: Linux kiste 2.4.4 #38 Tue May 8 00:13:02 CEST 2001 i686 unknown
Architecture: i686
SuSE 7.1
glibc 2.2
GNU ld version 2.11.90.0.4 (with BFD 2.11.90.0.4)
host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: i686-pc-linux-gnu
configured with: ../gcc/configure --enable-shared --disable-nls --enable-threads=posix --enable-long-long --enable-languages=c,c++,f77,objc
>Description:
G++ rejects the following legal code tl.C. The compiler cannot resolve
the call to f(rand), although there is a namespace std directive and
the rand function is imported into this namespace. If the scope of the
rand function is explicitly specified by a std:: or :: prefix, gcc 3.0
accepts the code. Please, note the "no matching function for call to
f(<unknown type>)" compiler message.

Gcc 2.95 has no problems compiling tl.C. 

>How-To-Repeat:
Source code tl.C
extern "C" int rand (void) throw ();
namespace std
{ 
    extern "C" int rand(void) throw(); 
    template <class T> void f(T a) {}
}
     
using namespace std;
     
int main()
{
    f(rand);
    f(std::rand);
    f(::rand);
}

Compiling tl.C
g++ -v tl.C 
Reading specs from /usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.0/specs
Configured with: ../gcc/configure --enable-shared --disable-nls --enable-threads=posix --enable-long-long --enable-languages=c,c++,f77,objc
Thread model: posix
gcc version 3.0 20010604 (prerelease)
 /usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.0/cc1plus -v -D__GNUC__=3 -D__GNUC_MINOR__=0 -D__GNUC_PATCHLEVEL__=0 -D__ELF__ -Dunix -Dlinux -D__ELF__ -D__unix__ -D__linux__ -D__unix -D__linux -Asystem=posix -D__STDC_HOSTED__=1 -Acpu=i386 -Amachine=i386 -Di386 -D__i386 -D__i386__ -D__tune_i686__ -D__tune_pentiumpro__ tl.C -D__GNUG__=3 -D_GNU_SOURCE -D__GXX_DEPRECATED -D__EXCEPTIONS -D__GXX_ABI_VERSION=100 -quiet -dumpbase tl.C -version -o /tmp/ccAIqTcf.s
GNU CPP version 3.0 20010604 (prerelease) (cpplib) (i386 Linux/ELF)
GNU C++ version 3.0 20010604 (prerelease) (i686-pc-linux-gnu)
	compiled by GNU C version 3.0 20010604 (prerelease).
#include "..." search starts here:
#include <...> search starts here:
 /usr/local/include/g++-v3
 /usr/local/include/g++-v3/i686-pc-linux-gnu
 /usr/local/include/g++-v3/backward
 /usr/local/include
 /usr/local/lib/gcc-lib/i686-pc-linux-gnu/3.0/include
 /usr/local/i686-pc-linux-gnu/include
 /usr/include
End of search list.
tl.C: In function `int main()':
tl.C:12: no matching function for call to `f(<unknown type>)'

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