Given

template <typename T, int I>
struct Value;
template <typename T>
struct Value<T, 0> {
};
template<typename TContainer, unsigned>
struct InternalMap {
};
template<typename T1>
struct Value<InternalMap<T1, 1>, 0 > {
  typedef char  Type;
};
template<typename T1>
typename Value<InternalMap<T1, 1>, 0 >::Type property();
void Test_Property() {
  property<char>();
}

clang -cc1 crashes with

Impossible TemplateArgument
UNREACHABLE executed at /home/espindola/llvm/llvm/tools/clang/lib/AST/TypeLoc.cpp:326!
0  clang           0x0000000001128702
1  clang           0x0000000001128b93
2  libpthread.so.0 0x00007f7150fe5fe0
3  libc.so.6       0x00007f7150442935 gsignal + 53
4  libc.so.6       0x00007f71504440e8 abort + 328
5  clang           0x00000000010fb009 llvm::llvm_unreachable_internal(char const*, char const*, unsigned int) + 457
6  clang           0x0000000001d30041 clang::TemplateSpecializationTypeLoc::initializeArgLocs(clang::ASTContext&, unsigned int, clang::TemplateArgument const*, clang::TemplateArgumentLocInfo*, clang::SourceLocation) + 417