argon2: only enable password-hash dependency if its been explicitly r…

…equested (#521)

argon2/Cargo.toml

@@ -33,10 +33,10 @@ password-hash = { version = "0.6.0-rc.0", features = ["rand_core"] }
 
 [features]
 default = ["alloc", "password-hash", "rand"]
-alloc = ["password-hash/alloc"]
-std = ["alloc", "password-hash/std"]
+alloc = ["password-hash?/alloc"]
+std = ["alloc", "password-hash?/std"]
 
-rand = ["password-hash/rand_core"]
+rand = ["password-hash?/rand_core"]
 simple = ["password-hash"]
 
 [lints.rust.unexpected_cfgs]

argon2/src/lib.rs

@@ -30,8 +30,11 @@
 //! password-based authentication. Do not use this API to derive cryptographic
 //! keys: see the "key derivation" usage example below.
 //!
-#![cfg_attr(feature = "std", doc = "```")]
-#![cfg_attr(not(feature = "std"), doc = "```ignore")]
+#![cfg_attr(all(feature = "password-hash", feature = "std"), doc = "```")]
+#![cfg_attr(
+    not(all(feature = "password-hash", feature = "std")),
+    doc = "```ignore"
+)]
 //! # fn main() -> Result<(), Box<dyn std::error::Error>> {
 //! use argon2::{
 //!     password_hash::{
@@ -65,8 +68,11 @@
 //! This API is useful for transforming a password into cryptographic keys for
 //! e.g. password-based encryption.
 //!
-#![cfg_attr(feature = "std", doc = "```")]
-#![cfg_attr(not(feature = "std"), doc = "```ignore")]
+#![cfg_attr(all(feature = "password-hash", feature = "std"), doc = "```")]
+#![cfg_attr(
+    not(all(feature = "password-hash", feature = "std")),
+    doc = "```ignore"
+)]
 //! # fn main() -> Result<(), Box<dyn std::error::Error>> {
 //! use argon2::Argon2;
 //!