Logging Rust programs

When executing your program, you need to set the RUST_LOG environment variable appropriately; it is (as far as this is concerned) a comma-separated key=value list; the keys are crate or module names, e.g. extra or std::option; the values are numbers, mapped to log levels:

• 1: error
• 2: warn
• 3: info
• 4: debug

(Each level includes the more significant levels.)

In Command Prompt, compiling and running myprog with showing warnings and errors would be something like:

rustc myprog.rs
set RUST_LOG=myprog=4
myprog.exe