Zig's Incremental Compilation Internals
Points and comments are a snapshot, not live.
Zig compiler achieves sub-100ms rebuilds via incremental compilation at function granularity.
Zig core team member explains how incremental compilation works: file-level ZIR caching and hashing detect changes, semantic analysis tracks dependencies between analysis units (type, value, body, layout) and source regions, codegen and linking are tightly integrated. Demonstrates rebuilds in 50-70ms for changes to a pixel editor app. Current support limited to self-hosted x86_64 backend (debug builds); LLVM backend not yet supported. Plans exist for future optimization passes.
What commenters are saying
Commenters praise Zig's toolchain progress. Two camps: those who see compilation speed as historically undervalued (citing Golang, Modula-2, Java vs C++) and those skeptical about safety tradeoffs. Rust developer notes Rust's safety checks aren't the root cause of slow compilation; highlights metaprogramming and crate-level compilation as bottlenecks. Author clarifies incremental compilation only works with Zig's self-hosted backend (x86_64), not LLVM or release builds; some optimizations (like inlining) may remain incompatible.