ccls
C/C++/ObjC language server supporting cross references & hierarchies
...It starts indexing the whole project (including subprojects if exist) parallelly when you open the first file, while the main thread can serve requests before the indexing is complete. Saving files will incrementally update the index. Hierarchies, call (caller/callee) hierarchy, inheritance (base/derived) hierarchy, member hierarchy. Symbol rename. Document symbols and approximate search of workspace symbol. Hover information. Diagnostics and code actions (clang FixIts). Semantic highlighting and preprocessor skipped regions.