Compilers and interpreters is one of the more rewarding niches in computer science — once the abstractions click, every programming language stops being magical. Modern compiler courses cover lexing, parsing, AST construction, semantic analysis, intermediate representation, optimization passes, and code generation, usually by building a small language end-to-end.
The tools have changed. LLVM is now the dominant backend for new languages (Rust, Swift, Crystal, Zig); ANTLR and tree-sitter handle parsing for tooling more than for production compilers; WebAssembly has become a credible target for languages that want to run in the browser. The Crafting Interpreters book by Bob Nystrom is still the most-recommended starting point for anyone serious about the subject.