Look for a global rustfmt.toml.

If no rustfmt.toml is found in the usual way, the directory 'rustfmt' in
the user's config directory is checked.

 - $XDG_CONFIG_HOME/rustfmt/ (or $HOME/.config/rustfmt/), or
 - $HOME/Library/Preferences/rustfmt/ on Mac, or
 - %AppData%\rustfmt\ on Windows.

Cargo.toml

@@ -55,6 +55,7 @@ failure = "0.1.3"
 bytecount = "0.5"
 unicode-width = "0.1.5"
 unicode_categories = "0.1.1"
+dirs = "1.0.4"
 
 # A noop dependency that changes in the Rust repository, it's a bit of a hack.
 # See the `src/tools/rustc-workspace-hack/README.md` file in `rust-lang/rust`

src/config/config_type.rs

@@ -345,9 +345,19 @@ macro_rules! create_config {
 
                         // If the current directory has no parent, we're done searching.
                         if !current.pop() {
-                            return Ok(None);
+                            break;
                         }
                     }
+
+                    // If none was found, check in the global configuration directory.
+                    if let Some(mut config_dir) = dirs::config_dir() {
+                        config_dir.push("rustfmt");
+                        if let Some(path) = get_toml_path(&config_dir)? {
+                            return Ok(Some(path));
+                        }
+                    }
+
+                    return Ok(None);
                 }
 
                 match resolve_project_file(dir)? {

src/lib.rs

@@ -13,6 +13,7 @@ extern crate derive_new;
 extern crate atty;
 extern crate bytecount;
 extern crate diff;
+extern crate dirs;
 extern crate failure;
 extern crate itertools;
 #[cfg(test)]