In the top right corner of the tooltip it will say either "Search-based" or "Precise" - in this case, you're right, we don't have the abseil-cpp repo indexed so

In the top right corner of the tooltip it will say either "Search-based" or "Precise" - in this case, you're right, we don't have the abseil-cpp repo indexed so it falls back to search-based as you describe. We do have a C++ code indexer in beta, https://github.com/sourcegraph/lsif-clang https://github.com/sourcegraph/lsif-clang - it is based on clang but C++ indexing is notably harder to do automatically/without-setup due to the varying build systems that need to be understood in order to invoke the compiler.