Cargo Features

Concurrent has no features set by default.

[dependencies]
concurrent = { version = "0.2.2", features = ["debug-tools"] }
debug-tools = backtrace

Affects debug::exec

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 debug-tools?