pub fn init_from_env() -> Result<(), String>Expand description
Install a subscriber configured entirely from the environment.
Nothing is enabled by default — a binary that sets neither variable logs
exactly as much as one with no subscriber at all. RUST_LOG is a full
Targets spec (gc=debug,cranelift_codegen=info); CLJRS_X_FLAG names
feature targets (apply_x_flag) and is layered on top, so both can be
used together.
This is what a generated AOT harness calls, so CLJRS_X_FLAG=debug:gc ./my-binary behaves the same as cljrs -X debug:gc run my-app.cljrs —
including on a value that does not parse. CLJRS_X_FLAG is ours alone and
has exactly one meaning, so a bad one is an Err here just as a bad -X is
a hard error in the CLI: the caller reports it and exits, because leaving
someone who asked for diagnostics with none is the one outcome nobody wants.
(RUST_LOG is treated more leniently — see apply_rust_log.)