The following code compiles without error and lead to a seg fault at runtime:
template <class U, class V>
struct A;
template <class V>
struct A<int, V> {
void f();
};
template struct A<int, int>;
int main() {
A<int, int> a;
a.f();
return 0;
}
Notice that there is no body defined for A<int, int>::f(). The correct link
error is reported when no explicit template instantiation is requested:
/tmp/ccycZSyE.o: In function `main':
testcase.cpp:(.text+0x10): undefined reference to `A<int, int>::f()'
collect2: ld returned 1 exit status
$g++ -v
Using built-in specs.
Target: x86_64-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian 4.4.2-7'
--with-bugurl=file:///usr/share/doc/gcc-4.4/README.Bugs
--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr --enable-shared
--enable-multiarch --enable-linker-build-id --with-system-zlib
--libexecdir=/usr/lib --without-included-gettext --enable-threads=posix
--with-gxx-include-dir=/usr/include/c++/4.4 --program-suffix=-4.4 --enable-nls
--enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc
--with-arch-32=i486 --with-tune=generic --enable-checking=release
--build=x86_64-linux-gnu --host=x86_64-linux-gnu --target=x86_64-linux-gnu
Thread model: posix
gcc version 4.4.2 (Debian 4.4.2-7)
--
Summary: Undefined reference not reported in case of explicit
template instantiation
Product: gcc
Version: 4.4.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: bastien_emmanuel at yahoo dot fr
GCC build triplet: x86_64-linux-gnu
GCC host triplet: x86_64-linux-gnu
GCC target triplet: x86_64-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=42608
