GCC generates a misleading diagnostic error with the following code: <code> typedef unsigned int int_t; namespace N { typedef unsigned long int_t; } using namespace N; int main() { N::int_t nu; // OK. int_t u; // Undeclared? Ambiguous! } </code>
$ g++ -v -save-temps tNS.cc Reading specs from /home/loose/linux/usr/local/gcc-3.4.2/lib/gcc/i686-pc-linux- gnu/3.4.2/specs Configured with: ../src/configure --prefix=/home/loose/linux/usr/local/gcc- 3.4.2 --enable-threads Thread model: posix gcc version 3.4.2 /home/loose/linux/usr/local/gcc-3.4.2/libexec/gcc/i686-pc-linux- gnu/3.4.2/cc1plus -E -quiet -v -D_GNU_SOURCE tNS.cc -mtune=pentiumpro -o tNS.ii ignoring nonexistent directory "/home/loose/linux/usr/local/gcc- 3.4.2/lib/gcc/i686-pc-linux-gnu/3.4.2/../../../../i686-pc-linux-gnu/include" #include "..." search starts here: #include <...> search starts here: /home/loose/linux/usr/local/gcc-3.4.2/lib/gcc/i686-pc-linux- gnu/3.4.2/../../../../include/c++/3.4.2 /home/loose/linux/usr/local/gcc-3.4.2/lib/gcc/i686-pc-linux- gnu/3.4.2/../../../../include/c++/3.4.2/i686-pc-linux-gnu /home/loose/linux/usr/local/gcc-3.4.2/lib/gcc/i686-pc-linux- gnu/3.4.2/../../../../include/c++/3.4.2/backward /usr/local/include /home/loose/linux/usr/local/gcc-3.4.2/include /home/loose/linux/usr/local/gcc-3.4.2/lib/gcc/i686-pc-linux-gnu/3.4.2/include /usr/include End of search list. /home/loose/linux/usr/local/gcc-3.4.2/libexec/gcc/i686-pc-linux- gnu/3.4.2/cc1plus -fpreprocessed tNS.ii -quiet -dumpbase tNS.cc - mtune=pentiumpro -auxbase tNS -version -o tNS.s GNU C++ version 3.4.2 (i686-pc-linux-gnu) compiled by GNU C version 3.4.2. GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072 tNS.cc: In function `int main()': tNS.cc:13: error: `int_t' undeclared (first use this function) tNS.cc:13: error: (Each undeclared identifier is reported only once for each function it appears in.) tNS.cc:13: error: expected `;' before "u" Note that GCC 3.2.2 also produces this type of diagnostic. The Intel compiler icc produces the following (more helpful) diagnostic: $ icc tNS.cc tNS.cc(13): error: "int_t" is ambiguous int_t u; // Undeclared? Ambiguous! ^ compilation aborted for tNS.cc (code 2) Browsing through the Bugzilla database I found a bug that appears to be related to bug #12582. -- Summary: Misleading diagnostic with ambiguous typedef Product: gcc Version: 3.4.2 Status: UNCONFIRMED Severity: normal Priority: P2 Component: c++ AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: loose at astron dot nl CC: gcc-bugs at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18097