When a namespace declares a function, and then "uses" another function with the same name from a different namespace, the using declaration seems to hide the function declaration. At least, when I define the function body later, the comiler complains that the function wasn't declared in the namespace. However, if I "use" the function first, and THEN declare it in the namespace, the definition of the function is accepted. (It's easer to show code than explain. See below.)
Using built-in specs. Target: i486-linux-gnu Configured with: ../src/configure -v --with-pkgversion='Ubuntu 4.3.2-1ubuntu11' --with-bugurl=file:///usr/share/doc/gcc-4.3/README.Bugs --enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/include/c++/4.3 --program-suffix=-4.3 --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-mpfr --enable-targets=all --enable-checking=release --build=i486-linux-gnu --host=i486-linux-gnu --target=i486-linux-gnu Thread model: posix gcc version 4.3.2 (Ubuntu 4.3.2-1ubuntu11) COLLECT_GCC_OPTIONS='-v' '-save-temps' '-mtune=generic' /usr/lib/gcc/i486-linux-gnu/4.3.2/cc1plus -E -quiet -v -D_GNU_SOURCE asdf.cpp -D_FORTIFY_SOURCE=2 -mtune=generic -fpch-preprocess -o asdf.ii ignoring nonexistent directory "/usr/local/include/i486-linux-gnu" ignoring nonexistent directory "/usr/lib/gcc/i486-linux-gnu/4.3.2/../../../../i486-linux-gnu/include" ignoring nonexistent directory "/usr/include/i486-linux-gnu" #include "..." search starts here: #include <...> search starts here: /usr/include/c++/4.3 /usr/include/c++/4.3/i486-linux-gnu /usr/include/c++/4.3/backward /usr/local/include /usr/lib/gcc/i486-linux-gnu/4.3.2/include /usr/lib/gcc/i486-linux-gnu/4.3.2/include-fixed /usr/include End of search list. COLLECT_GCC_OPTIONS='-v' '-save-temps' '-mtune=generic' /usr/lib/gcc/i486-linux-gnu/4.3.2/cc1plus -fpreprocessed asdf.ii -quiet -dumpbase asdf.cpp -mtune=generic -auxbase asdf -version -fstack-protector -o asdf.s GNU C++ (Ubuntu 4.3.2-1ubuntu11) version 4.3.2 (i486-linux-gnu) compiled by GNU C version 4.3.2, GMP version 4.2.2, MPFR version 2.3.2. GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 Compiler executable checksum: dc8f858cacda993dd8f70837f0d9565d asdf.cpp:15: error: void A::f(int) should have been declared inside A Source Code: void f() {} namespace A { void f(int); using ::f; } // // With the function declaration in namespace A appearing first, the // implementation below fails to compile. Switch the order (such that the // "using" appears first) and then it compiles. // // g++ /tmp/asdf.cpp // /tmp/asdf.cpp:15: error: void A::f(int) should have been declared inside A void A::f(int a) {} int main() { A::f(1); } -- Summary: using declaration appears to hide local declaration Product: gcc Version: 4.3.2 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: cuzdav at gmail dot com http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38799