Brownie having different behavior for library dependencies

Question

When I use my custom library, Brownie complains that the library is not deployed (UndeployedLibrary). But why doesn't it complain about other library files like the ones inside OpenZeppelin?

For example, in the image below, it doesn't throw any error for EnumerableSet but it throws UndeployedLibrary for Strings2Bytes32 that is written by myself.

I know that if I deploy the Strings2Bytes32 once is enough to get rid of the error, but I don't understand the difference between these two library files.

• What is the difference between these two?
• Can I set up Brownie in a way that it treats my own library files like the ones inside OpenZeppelin?

Answer 1

The explanation is in the libraries section.

Libraries can be seen as implicit base contracts of the contracts that use them. They will not be explicitly visible in the inheritance hierarchy, but calls to library functions look just like calls to functions of explicit base contracts (using qualified access like L.f()). [...]. To realize this in the EVM, code of internal library functions and all functions called from therein will at compile time be included in the calling contract, and a regular JUMP call will be used instead of a DELEGATECALL.