Allow banning or requiring specific features

Cargo.toml

@@ -103,3 +103,6 @@ lazy_static = "1.4.0"
 # We use this for creating fake crate directories for
 # crawling license files on disk
 tempfile = "3.1.0"
+
+[patch.crates-io]
+krates = { path = "../krates" }

docs/src/checks/bans/cfg.md

@@ -8,6 +8,30 @@ Contains all of the configuration for `cargo deny check bans`
 {{#include ../../../../tests/cfg/bans.toml}}
 ```
 
+### The `deny-features` field (optional)
+
+If any of the denied features for a specific crate is used in the
+dependency graph, cargo-deny will deny it.
+
+**Note:** If this field is provided, cargo-deny will not ban the crate,
+unless it uses denied features.
+
+### The `allow-features` field (optional)
+
+A specific crate can only use the features provided in this config entry.
+If this is an empty set, it will have no effect.
+
+**Note:** If this field is provided, cargo-deny will not ban the crate,
+unless it uses non-allowed features.
+
+### The `exact-features` field (optional)
+
+Makes `allow-features` strict. If this is true, the feature set
+of the crate must be exactly the same as the `allow-features` set.
+
+**Note:** If this field is provided, cargo-deny will not ban the crate,
+unless the feature set doesn't match exactly.
+
 ### The `multiple-versions` field (optional)
 
 Determines what happens when multiple versions of the same crate are