First draft of the language service plugin

.vscode/settings.json

@@ -7,5 +7,6 @@
         "out": true // set this to false to include "out" folder in search results
     },
     // Turn off tsc task auto detection since we have the necessary tasks as npm scripts
-    "typescript.tsc.autoDetect": "off"
+    "typescript.tsc.autoDetect": "off",
+    "typescript.tsserver.log": "normal"
 }

packages/language-service-plugin/example/.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+    "typescript.tsdk": "node_modules/typescript/lib"
+}

packages/language-service-plugin/example/index.ts

@@ -0,0 +1,9 @@
+let a;
+
+export function A(b: number): number {
+  if (true) {
+    return 1;
+  } {
+    3;
+  }
+}

packages/language-service-plugin/example/package.json

@@ -0,0 +1,8 @@
+{
+  "name": "@total-typescript/language-service-plugin-example",
+  "version": "0.1.0",
+  "dependencies": {
+    "better-ts-errors": "file:..",
+    "typescript": "^4.5.3"
+  }
+}

packages/language-service-plugin/example/tsconfig.json

@@ -0,0 +1,7 @@
+{
+  "compilerOptions": {
+    "plugins": [{
+      "name": "better-ts-errors"
+    }]
+  }
+}

packages/language-service-plugin/package.json

@@ -0,0 +1,15 @@
+{
+  "name": "better-ts-errors",
+  "version": "0.1.0",
+  "license": "MIT",
+  "main": "./out/index.js",
+  "private": true,
+  "files": ["./out/**"],
+  "scripts": {
+    "dev": "tsc --watch"
+  },
+  "devDependencies": {
+    "tsconfig": "workspace:*",
+    "typescript": "^4.5.3"
+  }
+}

packages/language-service-plugin/src/index.ts

@@ -0,0 +1,37 @@
+function init(modules: { typescript: typeof import("typescript/lib/tsserverlibrary") }) {
+  const ts = modules.typescript;
+
+  function create(info: ts.server.PluginCreateInfo) {
+    // Set up decorator object
+    const proxy: ts.LanguageService = Object.create(null);
+
+    for (let k of Object.keys(info.languageService) as Array<keyof ts.LanguageService>) {
+      const x = info.languageService[k]!;
+      // @ts-expect-error - JS runtime trickery which is tricky to type tersely
+      proxy[k] = (...args: Array<{}>) => x.apply(info.languageService, args);
+    }
+
+    // Remove specified entries from completion list
+    proxy.getCompletionsAtPosition = (fileName, position, options) => {
+      const prior = info.languageService.getCompletionsAtPosition(fileName, position, options);
+      if (!prior) {
+        return prior;
+      }
+      prior.entries = prior.entries.filter(e => e.name !== "caller");
+      const myItem: ts.CompletionEntry = {
+        name: 'MyTestKeyword',
+        kind: ts.ScriptElementKind.keyword,
+        sortText: 'My Test Keyword'
+      }
+      prior.entries.push(myItem);
+      return prior;
+    };
+
+    return proxy;
+  }
+
+  return { create };
+
+}
+
+export = init;

packages/language-service-plugin/tsconfig.json

@@ -0,0 +1,12 @@
+{
+  "extends": "tsconfig/base.json",
+  "compilerOptions": {
+    "outDir": "./out"
+  },
+  "include": [
+    "src"
+  ],
+  "exclude": [
+    "node_modules"
+  ]
+}