/tmp/cc5vQvfe.o: In function `main':
foo.cc:(.text.startup+0x1a): undefined reference to `B<int>::C<int> B<int>::fn<int, (int*)0>()'
foo.cc:(.text.startup+0x2b): undefined reference to `A<B<int> >::A(int, int)'
collect2: error: ld returned 1 exit status

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