Compiling the following one line:

   void f(int i = 0, int j) {}

produces the following error, as appropriate:

[jjamison@manzanita]$ /usr/misc/pkg/gcc-4.0.2/bin/g++ -c default.cc
default.cc: In function `void f(int, int)':
default.cc:1: error: default argument missing for parameter 2 of `void f(int, int)'
[jjamison@manzanita]$

However, compiling the following analogous code produces no errors, even though it should:

   struct T {
      T(int i = 0, int j) {}
      void m(int i = 0, int j) {}
   };

[jjamison@manzanita]$ /usr/misc/pkg/gcc-4.0.2/bin/g++ -c default.cc
[jjamison@manzanita]$

This behavior is replicated in 4.0.1, 4.0.0, 3.4.4, and 3.4.3.

[jjamison@manzanita]$ /usr/misc/pkg/gcc-4.0.2/bin/g++ -v
Using built-in specs.
Target: i686-pc-linux-gnu
Configured with: ../gcc-4.0.2/configure --prefix=/usr/misc/pkg/gcc-4.0.2 --enable-shared --enable-threads=posix --with-system-zlib --with-gnu-as --with-as=/usr/misc/pkg/binutils-2.16/bin/as --with-gnu-ld --with-ld=/usr/misc/pkg/binutils-2.16/bin/ld --enable-__cxa_atexit --enable-languages=c,c++
Thread model: posix
gcc version 4.0.2