Multiple definitions of a non-template class vs. a template class

Question

Why do compilers complain about a non-template class defined in multiple .cpp files but are fine with a template class the definition of which is duplicated across various .cpp files (via inclusion of the .inl file of the class), even if the class is explicitly instantiated in even multiple .cpp files?

Answer 1

The non-template case is because in that scenario your program violates the one definition rule so the linker (not compiler) will complain about multiple definitions.

For templates on the other hand, the language specifies that this must work and the linker sorts out what to do. I'm not 100% sure if an explicit template instantiation should be treated the same as a non-template function though.