Fix env::home_dir() deprecation warning.

* Import the `dirs` crate in `util/dir`.

* Replace uses of `env::home_dir()` with `dirs::home_dir()`.

* Reexport `dirs::home_dir`.

* Continue to use `std::env::home_dir` on Android, suppressing
  deprecation warnings.

parity/upgrade.rs

@@ -19,11 +19,11 @@
 use semver::{Version, SemVerError};
 use std::collections::*;
 use std::fs::{self, File, create_dir_all};
-use std::env;
 use std::io;
 use std::io::{Read, Write};
 use std::path::{PathBuf, Path};
-use dir::{DatabaseDirectories, default_data_path};
+#[cfg_attr(target_os="android", allow(deprecated))]
+use dir::{DatabaseDirectories, default_data_path, home_dir};
 use dir::helpers::replace_home;
 use journaldb::Algorithm;
 
@@ -201,7 +201,7 @@ fn upgrade_user_defaults(dirs: &DatabaseDirectories) {
 }
 
 pub fn upgrade_data_paths(base_path: &str, dirs: &DatabaseDirectories, pruning: Algorithm) {
-	if env::home_dir().is_none() {
+	if home_dir().is_none() {
 		return;
 	}
 

util/dir/Cargo.toml

@@ -8,3 +8,4 @@ license = "GPL3"
 ethereum-types = "0.3"
 journaldb = { path = "../journaldb" }
 app_dirs = { git = "https://github.com/paritytech/app-dirs-rs" }
+dirs = "1.0"

util/dir/src/helpers.rs

@@ -15,14 +15,16 @@
 // along with Parity.  If not, see <http://www.gnu.org/licenses/>.
 
 //! Directory helper functions
-use std::env;
+#[cfg_attr(target_os="android", allow(deprecated))]
+use ::home_dir;
 
 /// Replaces `$HOME` str with home directory path.
 pub fn replace_home(base: &str, arg: &str) -> String {
 	// the $HOME directory on mac os should be `~/Library` or `~/Library/Application Support`
 	// We use an `if` so that we don't need to call `home_dir()` if not necessary.
 	let r = if arg.contains("$HOME") {
-		arg.replace("$HOME", env::home_dir().expect("$HOME isn't defined").to_str().unwrap())
+		#[allow(deprecated)]
+		arg.replace("$HOME", home_dir().expect("$HOME isn't defined").to_str().unwrap())
 	} else {
 		arg.to_owned()
 	};

util/dir/src/lib.rs

@@ -20,9 +20,10 @@
 extern crate app_dirs;
 extern crate ethereum_types;
 extern crate journaldb;
+extern crate dirs;
 
 pub mod helpers;
-use std::{env, fs};
+use std::fs;
 use std::path::{PathBuf, Path};
 use ethereum_types::{H64, H256};
 use journaldb::Algorithm;
@@ -31,6 +32,13 @@ use app_dirs::{AppInfo, get_app_root, AppDataType};
 // re-export platform-specific functions
 use platform::*;
 
+#[cfg(not(target_os="android"))]
+pub use dirs::home_dir;
+#[cfg(target_os="android")]
+#[allow(deprecated)]
+pub use std::env::home_dir;
+
+
 /// Platform-specific chains path for standard client - Windows only
 #[cfg(target_os = "windows")] pub const CHAINS_PATH: &str = "$LOCAL/chains";
 /// Platform-specific chains path for light client - Windows only
@@ -237,7 +245,7 @@ pub fn default_hypervisor_path() -> PathBuf {
 
 /// Get home directory.
 fn home() -> PathBuf {
-	env::home_dir().expect("Failed to get home dir")
+	dirs::home_dir().expect("Failed to get home dir")
 }
 
 /// Geth path