fix: support generateTrace in non-build mode

Author: mkantor

README.md

@@ -347,11 +347,12 @@ yarn add --dev @types/webpack
 
 ## Profiling types resolution
 
-When using TypeScript 4.3.0 or newer in `build` mode you can profile long type checks by
+When using TypeScript 4.3.0 or newer you can profile long type checks by
 setting "generateTrace" compiler option. This is an instruction from [microsoft/TypeScript#40063](https://github.com/microsoft/TypeScript/pull/40063):
 
 1. Set "generateTrace": "{folderName}" in your `tsconfig.json` (under `compilerOptions`)
-2. Look in the resulting folder. There will be a `legend.json` telling you what went where.
+2. Look in the resulting folder. If you used build mode, there will be a `legend.json` telling you what went where.
+   Otherwise, there will be `trace.json` file and `types.json` files.
 3. Navigate to [edge://tracing](edge://tracing) or [chrome://tracing](chrome://tracing) and load `trace.json`
 4. Expand Process 1 with the little triangle in the left sidebar
 5. Click on different blocks to see their payloads in the bottom pane

src/typescript/worker/lib/program/program.ts

@@ -4,6 +4,7 @@ import { getConfigFilePathFromProgram, getParsedConfig } from '../config';
 import { updateDiagnostics, getDiagnosticsOfProgram } from '../diagnostics';
 import { emitDtsIfNeeded } from '../emit';
 import { createCompilerHost } from '../host/compiler-host';
+import { startTracingIfNeeded, stopTracingIfNeeded } from '../tracing';
 import { typescript } from '../typescript';
 
 let compilerHost: ts.CompilerHost | undefined;
@@ -16,6 +17,7 @@ export function useProgram() {
     compilerHost = createCompilerHost(parsedConfig);
   }
   if (!program) {
+    startTracingIfNeeded(parsedConfig.options);
     program = typescript.createProgram({
       rootNames: parsedConfig.fileNames,
       options: parsedConfig.options,
@@ -26,6 +28,7 @@ export function useProgram() {
 
   updateDiagnostics(getConfigFilePathFromProgram(program), getDiagnosticsOfProgram(program));
   emitDtsIfNeeded(program);
+  stopTracingIfNeeded(program);
 }
 
 export function invalidateProgram(withHost = false) {

src/typescript/worker/lib/tracing.ts

@@ -33,7 +33,7 @@ export function startTracingIfNeeded(compilerOptions: ts.CompilerOptions) {
   }
 }
 
-export function stopTracingIfNeeded(program: ts.BuilderProgram) {
+export function stopTracingIfNeeded(program: ts.Program | ts.BuilderProgram) {
   const compilerOptions = program.getCompilerOptions();
 
   if (

test/e2e/type-script-tracing.spec.ts

@@ -4,9 +4,13 @@ import { extractWebpackErrors } from './driver/webpack-errors-extractor';
 
 describe('TypeScript Tracing', () => {
   it.each([
+    { build: false, typescript: '~4.3.0' },
     { build: true, typescript: '~4.3.0' },
+    { build: false, typescript: '~4.4.0' },
     { build: true, typescript: '~4.4.0' },
+    { build: false, typescript: '~4.5.0' },
     { build: true, typescript: '~4.5.0' },
+    { build: false, typescript: '~4.6.0' },
     { build: true, typescript: '~4.6.0' },
   ])('can generate trace files for %p', async ({ build, ...dependencies }) => {
     await sandbox.load(path.join(__dirname, 'fixtures/typescript-basic'));