Cargo Features

problem = { version = "5.3.0", default-features = false, features = ["backtrace", "log"] }
default = backtrace, log

These default features are set whenever problem is added without default-features = false somewhere in the dependency tree.

Features from optional dependencies

In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features. These features may have been created by mistake, and this functionality may be removed in the future.

backtrace default
log default

Affects problem::logged, problem::format_panic_to_error_log