8 files changed, 49 insertions, 28 deletions

diff --git a/editors/code/src/client.ts b/editors/code/src/client.ts
index aaf2ef40e..540f7c9ea 100644
--- a/editors/code/src/client.ts
+++ b/editors/code/src/client.ts
@@ -3,6 +3,7 @@ import * as vscode from 'vscode';
 
 import { Config } from './config';
 import { CallHierarchyFeature } from 'vscode-languageclient/lib/callHierarchy.proposed';
+import { SemanticTokensFeature, DocumentSemanticsTokensSignature } from 'vscode-languageclient/lib/semanticTokens.proposed';
 
 export async function createClient(config: Config, serverPath: string): Promise<lc.LanguageClient> {
     // '.' Is the fallback if no folder is open
@@ -26,7 +27,7 @@ export async function createClient(config: Config, serverPath: string): Promise<
     const clientOptions: lc.LanguageClientOptions = {
         documentSelector: [{ scheme: 'file', language: 'rust' }],
         initializationOptions: {
-            publishDecorations: true,
+            publishDecorations: !config.highlightingSemanticTokens,
             lruCapacity: config.lruCapacity,
             maxInlayHintLength: config.maxInlayHintLength,
             cargoWatchEnable: cargoWatchOpts.enable,
@@ -41,6 +42,14 @@ export async function createClient(config: Config, serverPath: string): Promise<
             rustfmtArgs: config.rustfmtArgs,
         },
         traceOutputChannel,
+        middleware: {
+            // Workaround for https://github.com/microsoft/vscode-languageserver-node/issues/576
+            async provideDocumentSemanticTokens(document: vscode.TextDocument, token: vscode.CancellationToken, next: DocumentSemanticsTokensSignature) {
+                const res = await next(document, token);
+                if (res === undefined) throw new Error('busy');
+                return res;
+            }
+        } as any
     };
 
     const res = new lc.LanguageClient(
@@ -83,5 +92,10 @@ export async function createClient(config: Config, serverPath: string): Promise<
     // Here we want to just enable CallHierarchyFeature since it is available on stable.
     // Note that while the CallHierarchyFeature is stable the LSP protocol is not.
     res.registerFeature(new CallHierarchyFeature(res));
+
+    if (config.highlightingSemanticTokens) {
+        res.registerFeature(new SemanticTokensFeature(res));
+    }
+
     return res;
 }
diff --git a/editors/code/src/config.ts b/editors/code/src/config.ts
index 47e8cd45d..bf915102c 100644
--- a/editors/code/src/config.ts
+++ b/editors/code/src/config.ts
@@ -22,6 +22,7 @@ export class Config {
     private static readonly requiresReloadOpts = [
         "cargoFeatures",
         "cargo-watch",
+        "highlighting.semanticTokens"
     ]
         .map(opt => `${Config.rootSection}.${opt}`);
 
@@ -143,6 +144,7 @@ export class Config {
     // We don't do runtime config validation here for simplicity. More on stackoverflow:
     // https://stackoverflow.com/questions/60135780/what-is-the-best-way-to-type-check-the-configuration-for-vscode-extension
 
+    get highlightingSemanticTokens() { return this.cfg.get("highlighting.semanticTokens") as boolean; }
     get highlightingOn() { return this.cfg.get("highlightingOn") as boolean; }
     get rainbowHighlightingOn() { return this.cfg.get("rainbowHighlightingOn") as boolean; }
     get lruCapacity() { return this.cfg.get("lruCapacity") as null | number; }
diff --git a/editors/code/src/inlay_hints.ts b/editors/code/src/inlay_hints.ts
index 5951cf1b4..6871bc111 100644
--- a/editors/code/src/inlay_hints.ts
+++ b/editors/code/src/inlay_hints.ts
@@ -42,12 +42,14 @@ export function activateInlayHints(ctx: Ctx) {
 const typeHintDecorationType = vscode.window.createTextEditorDecorationType({
     after: {
         color: new vscode.ThemeColor('rust_analyzer.inlayHint'),
+        fontStyle: "normal",
     },
 });
 
 const parameterHintDecorationType = vscode.window.createTextEditorDecorationType({
     before: {
         color: new vscode.ThemeColor('rust_analyzer.inlayHint'),
+        fontStyle: "normal",
     },
 });
 
diff --git a/editors/code/src/installation/download_artifact.ts b/editors/code/src/installation/download_artifact.ts
index 356723aba..97e4d67c2 100644
--- a/editors/code/src/installation/download_artifact.ts
+++ b/editors/code/src/installation/download_artifact.ts
@@ -1,11 +1,10 @@
 import * as vscode from "vscode";
 import * as path from "path";
 import { promises as fs } from "fs";
-import { strict as assert } from "assert";
 
 import { ArtifactReleaseInfo } from "./interfaces";
 import { downloadFile } from "./download_file";
-import { throttle } from "throttle-debounce";
+import { assert } from "../util";
 
 /**
  * Downloads artifact from given `downloadUrl`.
@@ -20,11 +19,10 @@ export async function downloadArtifact(
     installationDir: string,
     displayName: string,
 ) {
-    await fs.mkdir(installationDir).catch(err => assert.strictEqual(
-        err?.code,
-        "EEXIST",
+    await fs.mkdir(installationDir).catch(err => assert(
+        err?.code === "EEXIST",
         `Couldn't create directory "${installationDir}" to download ` +
-        `${artifactFileName} artifact: ${err.message}`
+        `${artifactFileName} artifact: ${err?.message}`
     ));
 
     const installationPath = path.join(installationDir, artifactFileName);
@@ -38,19 +36,15 @@ export async function downloadArtifact(
         async (progress, _cancellationToken) => {
             let lastPrecentage = 0;
             const filePermissions = 0o755; // (rwx, r_x, r_x)
-            await downloadFile(downloadUrl, installationPath, filePermissions, throttle(
-                200,
-                /* noTrailing: */ true,
-                (readBytes, totalBytes) => {
-                    const newPercentage = (readBytes / totalBytes) * 100;
-                    progress.report({
-                        message: newPercentage.toFixed(0) + "%",
-                        increment: newPercentage - lastPrecentage
-                    });
+            await downloadFile(downloadUrl, installationPath, filePermissions, (readBytes, totalBytes) => {
+                const newPercentage = (readBytes / totalBytes) * 100;
+                progress.report({
+                    message: newPercentage.toFixed(0) + "%",
+                    increment: newPercentage - lastPrecentage
+                });
 
-                    lastPrecentage = newPercentage;
-                })
-            );
+                lastPrecentage = newPercentage;
+            });
         }
     );
 }
diff --git a/editors/code/src/installation/download_file.ts b/editors/code/src/installation/download_file.ts
index 319cb995c..ee8949d61 100644
--- a/editors/code/src/installation/download_file.ts
+++ b/editors/code/src/installation/download_file.ts
@@ -2,8 +2,7 @@ import fetch from "node-fetch";
 import * as fs from "fs";
 import * as stream from "stream";
 import * as util from "util";
-import { strict as assert } from "assert";
-import { log } from "../util";
+import { log, assert } from "../util";
 
 const pipeline = util.promisify(stream.pipeline);
 
diff --git a/editors/code/src/installation/server.ts b/editors/code/src/installation/server.ts
index cb5e56844..6a6cf4f8c 100644
--- a/editors/code/src/installation/server.ts
+++ b/editors/code/src/installation/server.ts
@@ -1,13 +1,12 @@
 import * as vscode from "vscode";
 import * as path from "path";
-import { strict as assert } from "assert";
 import { promises as dns } from "dns";
 import { spawnSync } from "child_process";
 
 import { BinarySource } from "./interfaces";
 import { fetchArtifactReleaseInfo } from "./fetch_artifact_release_info";
 import { downloadArtifact } from "./download_artifact";
-import { log } from "../util";
+import { log, assert } from "../util";
 
 export async function ensureServerBinary(source: null | BinarySource): Promise<null | string> {
     if (!source) {
diff --git a/editors/code/src/main.ts b/editors/code/src/main.ts
index 424ff1ac3..ecf53cf77 100644
--- a/editors/code/src/main.ts
+++ b/editors/code/src/main.ts
@@ -89,7 +89,9 @@ export async function activate(context: vscode.ExtensionContext) {
 
     activateStatusDisplay(ctx);
 
-    activateHighlighting(ctx);
+    if (!ctx.config.highlightingSemanticTokens) {
+        activateHighlighting(ctx);
+    }
     activateInlayHints(ctx);
 }
 
diff --git a/editors/code/src/util.ts b/editors/code/src/util.ts
index 68c2a94d0..f56c6bada 100644
--- a/editors/code/src/util.ts
+++ b/editors/code/src/util.ts
@@ -1,22 +1,31 @@
 import * as lc from "vscode-languageclient";
 import * as vscode from "vscode";
+import { strict as nativeAssert } from "assert";
 
-let enabled: boolean = false;
+export function assert(condition: boolean, explanation: string): asserts condition {
+    try {
+        nativeAssert(condition, explanation);
+    } catch (err) {
+        log.error(`Assertion failed:`, explanation);
+        throw err;
+    }
+}
 
 export const log = {
+    enabled: true,
     debug(message?: any, ...optionalParams: any[]): void {
-        if (!enabled) return;
+        if (!log.enabled) return;
         // eslint-disable-next-line no-console
         console.log(message, ...optionalParams);
     },
     error(message?: any, ...optionalParams: any[]): void {
-        if (!enabled) return;
+        if (!log.enabled) return;
         debugger;
         // eslint-disable-next-line no-console
         console.error(message, ...optionalParams);
     },
     setEnabled(yes: boolean): void {
-        enabled = yes;
+        log.enabled = yes;
     }
 };