fix: in VSCode, correctly resolve relative paths to errors

VS Code problem matcher are restricted to be static "regexes". You can't
create a problem matcher dynamically, and you can't use custom code in
lieu of problem matcher.

This creates a problem for rust/cargo compiler errors. They use paths
relative to the root of the Cargo workspace, but VS Code doesn't
necessary know where that root is.

Luckily, there's a way out: our current problem matcher is defined like
this:

    "fileLocation": [ "autoDetect", "${workspaceRoot}" ],

That means that relative pahts would be resoleved relative to workspace
root. VS Code allows to specify a command inside `${}`. So we can plug
custom logic there to fetch Cargo's workspace root!

And that's exactly what this PR is doing!

Author: matklad

editors/code/package.json

@@ -1301,6 +1301,12 @@
                     "endsPattern": "^\\[Finished running\\b"
                 },
                 "pattern": "$rustc"
+            },
+            {
+                "name": "rustc-run",
+                "base": "$rustc",
+                "fileLocation": ["autoDetect", "${command:rust-analyzer.cargoWorkspaceRootForCurrentRun}"],
+                "pattern": "$rustc-run"
             }
         ],
         "colors": [

editors/code/src/commands.ts

@@ -842,6 +842,7 @@ export function run(ctx: Ctx): Cmd {
         item.detail = "rerun";
         prevRunnable = item;
         const task = await createTask(item.runnable, ctx.config);
+        ctx.cargoWorkspaceRootForCurrentRun = item.cargoWorkspaceRoot;
         return await vscode.tasks.executeTask(task);
     };
 }
@@ -946,3 +947,6 @@ export function linkToCommand(ctx: Ctx): Cmd {
         }
     };
 }
+export function getCargoWorkspaceDir(ctx: Ctx): Cmd {
+    return async () => ctx.cargoWorkspaceRootForCurrentRun
+}

editors/code/src/ctx.ts

@@ -17,6 +17,10 @@ export type Workspace =
       };
 
 export class Ctx {
+    // Helps VS Code to correctly link problems from runnables. This is used by
+    // `rust-analyzer.cargoWorkspaceRootForCurrentRun` command of $rustc-run problem matcher.
+    cargoWorkspaceRootForCurrentRun?: string = undefined;
+
     private constructor(
         readonly config: Config,
         private readonly extCtx: vscode.ExtensionContext,

editors/code/src/main.ts

@@ -189,6 +189,7 @@ async function initCommonContext(context: vscode.ExtensionContext, ctx: Ctx) {
     ctx.registerCommand("resolveCodeAction", commands.resolveCodeAction);
     ctx.registerCommand("applyActionGroup", commands.applyActionGroup);
     ctx.registerCommand("gotoLocation", commands.gotoLocation);
+    ctx.registerCommand("cargoWorkspaceRootForCurrentRun", commands.getCargoWorkspaceDir);
 
     ctx.registerCommand("linkToCommand", commands.linkToCommand);
 }
@@ -216,7 +217,7 @@ async function bootstrap(
     if (!path) {
         throw new Error(
             "Rust Analyzer Language Server is not available. " +
-                "Please, ensure its [proper installation](https://rust-analyzer.github.io/manual.html#installation)."
+            "Please, ensure its [proper installation](https://rust-analyzer.github.io/manual.html#installation)."
         );
     }
 
@@ -325,11 +326,11 @@ async function getServer(
     await state.updateServerVersion(undefined);
     await vscode.window.showErrorMessage(
         "Unfortunately we don't ship binaries for your platform yet. " +
-            "You need to manually clone the rust-analyzer repository and " +
-            "run `cargo xtask install --server` to build the language server from sources. " +
-            "If you feel that your platform should be supported, please create an issue " +
-            "about that [here](https://github.com/rust-lang/rust-analyzer/issues) and we " +
-            "will consider it."
+        "You need to manually clone the rust-analyzer repository and " +
+        "run `cargo xtask install --server` to build the language server from sources. " +
+        "If you feel that your platform should be supported, please create an issue " +
+        "about that [here](https://github.com/rust-lang/rust-analyzer/issues) and we " +
+        "will consider it."
     );
     return undefined;
 }
@@ -355,11 +356,11 @@ function warnAboutExtensionConflicts() {
         vscode.window
             .showWarningMessage(
                 `You have both the rust-analyzer (rust-lang.rust-analyzer) and Rust (rust-lang.rust) ` +
-                    "plugins enabled. These are known to conflict and cause various functions of " +
-                    "both plugins to not work correctly. You should disable one of them.",
+                "plugins enabled. These are known to conflict and cause various functions of " +
+                "both plugins to not work correctly. You should disable one of them.",
                 "Got it"
             )
-            .then(() => {}, console.error);
+            .then(() => { }, console.error);
     }
 }
 

editors/code/src/run.ts

@@ -89,12 +89,14 @@ export async function selectRunnable(
 
 export class RunnableQuickPick implements vscode.QuickPickItem {
     public label: string;
+    public cargoWorkspaceRoot?: string
     public description?: string | undefined;
     public detail?: string | undefined;
     public picked?: boolean | undefined;
 
     constructor(public runnable: ra.Runnable) {
         this.label = runnable.label;
+        this.cargoWorkspaceRoot = runnable.args.workspaceRoot
     }
 }
 

editors/code/src/tasks.ts

@@ -128,7 +128,7 @@ export async function buildCargoTask(
         name,
         TASK_SOURCE,
         exec,
-        ["$rustc"]
+        ["$rustc-run"]
     );
 }