Remove lib folder (LKG) and use node_modules for building (microsoft#52226)

Author: jakebailey

.github/workflows/ci.yml

@@ -96,6 +96,26 @@ jobs:
       with:
         node-version: "*"
         check-latest: true
+    
+    # Pre-build the base branch so we can check lib folder size changes.
+    # Note that github.sha points to a merge commit, meaning we're testing
+    # the base branch versus the base branch with the PR applied.
+    - if: github.event_name == 'pull_request'
+      run: |
+        if [ ! -d lib ]; then
+          git fetch origin ${{ github.base_ref }}
+          git checkout ${{ github.base_ref }}
+          npm ci
+          npx hereby lkg
+          mkdir /tmp/lkg
+          mv lib /tmp/lkg/
+          git restore lib
+          git clean -fdx lib
+          git checkout ${{ github.sha }}
+          rm -rf lib
+          mv /tmp/lkg/lib .
+        fi
+
     - run:  npm ci
 
     - run: npx hereby lkg

.gitignore

@@ -62,3 +62,4 @@ TEST-results.xml
 package-lock.json
 .eslintcache
 *v8.log
+lib/

.vscode/settings.template.json

@@ -1,9 +1,6 @@
 // Rename this file 'settings.json' or merge its
 // contents into your existing settings.
 {
-    // To use the last-known-good (LKG) compiler version:
-    // "typescript.tsdk": "lib"
-
     // To use the locally built compiler, after 'npm run build':
     // "typescript.tsdk": "built/local"
 

.vscode/tasks.json

@@ -25,7 +25,7 @@
             "label": "tsc: watch ./src",
             "type": "shell",
             "command": "node",
-            "args": ["${workspaceFolder}/lib/tsc.js", "--build", "${workspaceFolder}/src", "--watch"],
+            "args": ["${workspaceFolder}/node_modules/tsc.js", "--build", "${workspaceFolder}/src", "--watch"],
             "group": "build",
             "isBackground": true,
             "problemMatcher": [

Herebyfile.mjs

@@ -6,7 +6,6 @@ import del from "del";
 import esbuild from "esbuild";
 import { EventEmitter } from "events";
 import fs from "fs";
-import fsExtra from "fs-extra";
 import _glob from "glob";
 import { task } from "hereby";
 import path from "path";
@@ -833,11 +832,19 @@ export const produceLKG = task({
         if (missingFiles.length > 0) {
             throw new Error("Cannot replace the LKG unless all built targets are present in directory 'built/local/'. The following files are missing:\n" + missingFiles.join("\n"));
         }
-        const sizeBefore = getDirSize("lib");
+
+        /** @type {number | undefined} */
+        let sizeBefore;
+        if (fs.existsSync("lib")) {
+            sizeBefore = getDirSize("lib");
+        }
         await exec(process.execPath, ["scripts/produceLKG.mjs"]);
-        const sizeAfter = getDirSize("lib");
-        if (sizeAfter > (sizeBefore * 1.10)) {
-            throw new Error("The lib folder increased by 10% or more. This likely indicates a bug.");
+
+        if (sizeBefore !== undefined) {
+            const sizeAfter = getDirSize("lib");
+            if (sizeAfter > (sizeBefore * 1.10)) {
+                throw new Error("The lib folder increased by 10% or more. This likely indicates a bug.");
+            }
         }
     }
 });
@@ -884,14 +891,3 @@ export const help = task({
     hiddenFromTaskList: true,
     run: () => exec("hereby", ["--tasks"], { hidePrompt: true }),
 });
-
-export const bumpLkgToNightly = task({
-    name: "bump-lkg-to-nightly",
-    description: "Bumps typescript in package.json to the latest nightly and copies it to LKG.",
-    run: async () => {
-        await exec("npm", ["install", "--save-dev", "--save-exact", "typescript@next"]);
-        await fs.promises.rm("lib", { recursive: true, force: true });
-        await fsExtra.copy("node_modules/typescript/lib", "lib");
-        await fs.promises.writeFile("lib/.gitattributes", "* text eol=lf");
-    }
-});