Is there a way to statically disable Rust logging in production builds of my application? [duplicate]

Question

I have a WebAssembly module written in Rust that performs logging for debug purposes via the log crate during development. I notice that, even when I don't configure a logger, the formatting and calls to internal log functions remain in the generated WebAssembly module. This wastes bytes since the output of those functions will never be used/displayed.

Is there any way to statically disable logging without having to remove the log macro calls in the code? Additionally, is there a way to only disable this in release builds?

Answer 1

Yes; the log crate provides features flags that allow logging to be statically disabled at compile time up to a certain level.

If you want to completely disable all logging in release builds but keep normal logging in debug builds, change your entry in Cargo.toml to include the release_max_level_off feature like this:

log = { version = "0.4", features = ["release_max_level_off"] }

This will cause all calls to logging functions to be eliminated from the resulting binary, taking any related formatting code with it via dead code elimination.