c++/1883: Function lookup in template constructors fails when using namespace.

[Carlo dot Wood at alinoe dot com]

>Number:         1883
>Category:       c++
>Synopsis:       Function lookup in template constructors fails when using namespace.
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          rejects-legal
>Submitter-Id:   net
>Arrival-Date:   Mon Feb 05 21:06:01 PST 2001
>Closed-Date:
>Last-Modified:
>Originator:     Carlo Wood <carlo@alinoe.com>
>Release:        2.97 20010122 (experimental)
>Organization:
>Environment:
System: Linux ansset 2.4.0-test10 #2 Thu Nov 2 10:05:20 CET 2000 i686 unknown
Architecture: i686
host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: i686-pc-linux-gnu
configured with: ../gcc-cvs/configure --prefix=/usr/local/gcc --enable-shared --with-gnu-as --with-gnu-ld --enable-languages=c++ : (reconfigured)  : (reconfigured) ../gcc-cvs/configure --prefix=/usr/local/gcc --enable-shared --with-gnu-as --with-gnu-ld --enable-languages=c++
>Description:
	A function which is declared in a namespace will not be seen in the
	constructor of a template class when the namespace is not explicitely
	given (ie N::n() works) but a "using namespace N;" is used instead.
>How-To-Repeat:
	The following code snippet reproduces the error:
	-----------------------------------------------
	namespace N
	{
	  void n(void) { }
	}
	 
	template<typename T>
	  class A {
	  public:
	    A(void)
	    {
	      using namespace N;
	      n();
	    }
	  };
	 
	class B { };
	 
	A<B> a;
	-----------------------------------------------
	g++-cvs -v -c test.cc
	Reading specs from /usr/local/gcc/lib/gcc-lib/i686-pc-linux-gnu/2.97/specs
	Configured with: ../gcc-cvs/configure --prefix=/usr/local/gcc --enable-shared --with-gnu-as --with-gnu-ld --enable-languages=c++ : (reconfigured)  : (reconfigured) ../gcc-cvs/configure --prefix=/usr/local/gcc --enable-shared --with-gnu-as --with-gnu-ld --enable-languages=c++
	gcc version 2.97 20010122 (experimental)
	 /usr/local/gcc/lib/gcc-lib/i686-pc-linux-gnu/2.97/cc1plus -v -iprefix /usr/local/bin/../lib/gcc-lib/i686-pc-linux-gnu/2.97/ -D__GNUC__=2 -D__GNUC_MINOR__=97 -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__ test.cc -D__GNUG__=2 -D_GNU_SOURCE -D__GXX_ABI_VERSION=100 -quiet -dumpbase test.cc -version -o /tmp/ccxY4RYU.s
	GNU CPP version 2.97 20010122 (experimental) (cpplib) (i386 Linux/ELF)
	GNU CPP version 2.97 20010122 (experimental) (cpplib) (i386 Linux/ELF)
	GNU C++ version 2.97 20010122 (experimental) (i686-pc-linux-gnu)
		compiled by GNU C version 2.97 20010122 (experimental).
	ignoring nonexistent directory "/usr/local/include/g++-"
	ignoring nonexistent directory "/usr/local/lib/gcc-lib/i686-pc-linux-gnu/2.97/include"
	ignoring nonexistent directory "/usr/local/i686-pc-linux-gnu/include"
	ignoring nonexistent directory "/usr/local/gcc/i686-pc-linux-gnu/include/g++-"
	#include "..." search starts here:
	#include <...> search starts here:
	 /usr/local/gcc/include/g++-
	 /usr/local/include
	 /usr/local/gcc/lib/gcc-lib/i686-pc-linux-gnu/2.97/include
	 /usr/local/gcc/i686-pc-linux-gnu/include
	 /usr/include
	End of search list.
	test.cc: In constructor `A<T>::A() [with T = B]':
	test.cc:18:   instantiated from here
	test.cc:12: `n' undeclared (first use this function)
	test.cc:12: (Each undeclared identifier is reported only once for each function
	   it appears in.)
>Fix:
	A work around is to explicitely give the namespace and write:
	N::n();
>Release-Note:
>Audit-Trail:
>Unformatted: