>Submitter-Id: net-debian
>Originator: Seth M LaForge
>Organization:
>Confidential: no
>Synopsis: The 'using typename' construct won't compile
>Severity: serious
>Priority: medium
>Category: c++
>Class: rejects-legal
>Release: 3.0 20010526 (Debian prerelease) (Debian testing/unstable)
>Environment:
System: Linux burn 2.2.18 #1 Thu Dec 14 09:22:25 PST 2000 i686 unknown
Architecture: i686
host: i386-pc-linux-gnu
build: i386-pc-linux-gnu
target: i386-pc-linux-gnu
configured with: ../src/configure -v
--enable-languages=c,c++,java,f77,proto,objc --prefix=/usr
--infodir=/share/info --mandir=/share/man --enable-shared --with-gnu-as
--with-gnu-ld --with-system-zlib --enable-long-long --enable-nls --without-x
--without-included-gettext --disable-checking --enable-threads=posix
--enable-java-gc=boehm --with-cpp-install-dir=bin --enable-objc-gc i386-linux
>Description:
C++ allows the word 'typename' after a 'using' directive. _The C++
Programming Language_ (third edition) [Stroustrup], section A.7
(Grammar/Declarations) defines the using directive:
using-declaration:
"using" "typename"(opt) "::"(opt) nested-name-specifier
unqualified-id ";"
>How-To-Repeat:
Attempt to compile the following:
struct C {
typedef int INT;
};
struct D : public C {
using typename C::INT;
};
int main() {
D::INT x = 666;
}
The compiler complains:
test.cc:6: parse error before `typename'
>Fix:
I'm not sure if there are cases in which the 'typename' portion is
required. I've seen it in production code (the loki library, from _Modern C++
Design_ [Alexandrescu].
