Use rustfmt when run rls mode (#257)

doc/main.md

@@ -16,8 +16,8 @@ The second one is recommended and at some point the first one will be removed.
 
 But Legacy Mode should work just fine and if it doesn't, open an issue.
 
-Unfortunately, sometimes RLS does not work as one can expect.
-In this situation one can set `"rust.forceLegacyMode"` to `true` and the extension will function in Legacy Mode.
+When the extension starts the first time, it asks to choose one of the modes.
+The chosen mode is stored in `"rust.mode"` and it can be changed by users.
 
 Each mode is described in detail on its own page.
 

doc/rls_mode/main.md

@@ -12,10 +12,13 @@ The type of the parameter is an object with the following fields:
 * `"args"` - an array of strings. Arguments to pass to the executable
 * `"env"` - an environment to append to the current environment to execute the executable
 * `"revealOutputChannelOn"` - a string. Specifies the condition when the output channel should be revealed
+* `"useRustfmt"` - either a boolean or `null`. Specifies whether [rustfmt] should be used for formatting
 
 By default, it is `null`.
 
-### The revealOutputChannelOn configuration parameter
+### More about configuration parameter
+
+#### revealOutputChannelOn
 
 This determines when the Output channel is revealed.
 
@@ -26,6 +29,14 @@ The possible values are:
 * `"error"` - revealed on each error line (default)
 * `"never"` - the output channel never reveals automatically
 
+#### useRustfmt
+
+The possible values are:
+
+* `null` - the extension will ask whether [rustfmt] should be used for formatting
+* `false` - the extension will not use [rustfmt] for formatting
+* `true` - the extension will use [rustfmt] for formatting
+
 ## Setting up
 
 The recommended way to set RLS up is using rustup. You should use rustup unless rustup does not suit you.
@@ -157,3 +168,5 @@ Clicking on the indicator restarts RLS.
 
 ## Enabling formatting and renaming
 Create a `rls.toml` file in your project's root and add `unstable_features = true` and RLS will be able to auto format on save and renaming.
+
+[rustfmt]: https://github.com/rust-lang-nursery/rustfmt

package.json

@@ -504,6 +504,14 @@
                 "never"
               ],
               "type": "string"
+            },
+            "useRustfmt": {
+              "default": null,
+              "description": "Specified whether rustfmt should be used for formatting",
+              "type": [
+                "boolean",
+                "null"
+              ]
             }
           }
         }

src/components/configuration/RlsConfiguration.ts

@@ -15,6 +15,7 @@ export class RlsConfiguration {
     private _userArgs: string[];
     private _userEnv: object;
     private _revealOutputChannelOn: RevealOutputChannelOn;
+    private _useRustfmt: boolean | undefined;
 
     /**
      * Creates a new instance of the class
@@ -71,20 +72,50 @@ export class RlsConfiguration {
         return this._revealOutputChannelOn;
     }
 
+    /**
+     * Returns whether rustfmt should be used for formatting
+     */
+    public getUseRustfmt(): boolean | undefined {
+        return this._useRustfmt;
+    }
+
+    /**
+     * Updates the property "useRustfmt" in the user configuration
+     * @param value The new value
+     */
+    public setUseRustfmt(value: boolean | undefined): void {
+        if (this._useRustfmt === value) {
+            return;
+        }
+        this._useRustfmt = value;
+        const suitableValue = typeof value === 'boolean' ? value : null;
+        updateUserConfigurationParameter(c => { c.useRustfmt = suitableValue; });
+    }
+
     private constructor(rustup: Rustup | undefined, rustSource: RustSource, executableUserPath: string | undefined) {
         this._rustup = rustup;
         this._rustSource = rustSource;
         this._executableUserPath = executableUserPath;
         this._userArgs = getUserArgs();
         this._userEnv = getUserEnv();
         this._revealOutputChannelOn = getUserRevealOutputChannelOn();
+        this._useRustfmt = getUserUseRustfmt();
     }
 }
 
 function getUserConfiguration(): any {
     return Configuration.getConfiguration()['rls'];
 }
 
+function updateUserConfigurationParameter(updateParameter: (c: any) => void): void {
+    let configuration = getUserConfiguration();
+    if (!configuration) {
+        configuration = {};
+    }
+    updateParameter(configuration);
+    Configuration.getConfiguration().update('rls', configuration, true);
+}
+
 function getExecutableUserPath(): string | undefined {
     const configuration = getUserConfiguration();
     if (!configuration) {
@@ -140,6 +171,18 @@ function getUserRevealOutputChannelOn(): RevealOutputChannelOn {
     }
 }
 
+function getUserUseRustfmt(): boolean | undefined {
+    const configuration = getUserConfiguration();
+    if (!configuration) {
+        return undefined;
+    }
+    const useRustfmt = configuration.useRustfmt;
+    if (typeof useRustfmt === 'boolean') {
+        return useRustfmt;
+    } else {
+        return undefined;
+    }
+}
 
 async function getCheckedExecutableUserPath(): Promise<string | undefined> {
     const path = getExecutableUserPath();