Fixes to support builder api for compiling https://github.com/johnnyreilly/typescript-ts-loader-watch-api-illustration correctly

src/index.ts

@@ -201,7 +201,7 @@ function updateFileInCache(filePath: string, contents: string, instance: TSInsta
         file.text = contents;
         instance.version!++;
         if (instance.watchHost && fileWatcherEventKind === undefined) {
-            instance.watchHost.invokeFileWatcher(filePath, instance.compiler.FileWatcherEventKind.Changed);
+            fileWatcherEventKind = instance.compiler.FileWatcherEventKind.Changed;
         }
     }
 

src/instances.ts

@@ -22,6 +22,18 @@ import {
 
 const instances = <TSInstances> {};
 
+function ensureProgram(instance: TSInstance) {
+    if (instance && instance.watchHost) {
+        if (instance.changedFilesList) {
+            instance.watchHost.updateRootFileNames();
+        }
+        if (instance.watchOfFilesAndCompilerOptions) {
+            instance.program = instance.watchOfFilesAndCompilerOptions.getProgram().getProgram();
+        }
+        return instance.program;
+    }
+    return undefined;
+}
 /**
  * The loader is executed once for each file seen by webpack. However, we need to keep
  * a persistent instance of TypeScript that contains all of the files in the program
@@ -35,14 +47,7 @@ export function getTypeScriptInstance(
 ): { instance?: TSInstance, error?: WebpackError } {
     if (hasOwnProperty(instances, loaderOptions.instance)) {
         const instance = instances[loaderOptions.instance];
-        if (instance && instance.watchHost) {
-            if (instance.changedFilesList) {
-                instance.watchHost.updateRootFileNames();
-            }
-            if (instance.watchOfFilesAndCompilerOptions) {
-                instance.program = instance.watchOfFilesAndCompilerOptions.getProgram().getProgram();
-            }
-        }
+        ensureProgram(instance);
         return { instance: instances[loaderOptions.instance] };
     }
 
@@ -169,8 +174,8 @@ function successfulTypeScriptInstance(
         log.logInfo("Using watch api");
 
         // If there is api available for watch, use it instead of language service
-        const watchHost = makeWatchHost(scriptRegex, log, loader, instance, loaderOptions.appendTsSuffixTo, loaderOptions.appendTsxSuffixTo);
-        instance.watchOfFilesAndCompilerOptions = compiler.createWatchProgram(watchHost);
+        instance.watchHost = makeWatchHost(scriptRegex, log, loader, instance, loaderOptions.appendTsSuffixTo, loaderOptions.appendTsxSuffixTo);
+        instance.watchOfFilesAndCompilerOptions = compiler.createWatchProgram(instance.watchHost);
         instance.program = instance.watchOfFilesAndCompilerOptions.getProgram().getProgram();
     }
     else {
@@ -185,12 +190,13 @@ function successfulTypeScriptInstance(
 }
 
 export function getEmitOutput(instance: TSInstance, filePath: string) {
-    if (instance.program) {
+    const program = ensureProgram(instance);
+    if (program) {
         const outputFiles: typescript.OutputFile[] = [];
         const writeFile = (fileName: string, text: string, writeByteOrderMark: boolean) =>
             outputFiles.push({ name: fileName, writeByteOrderMark, text });
-        const sourceFile = instance.program.getSourceFile(filePath);
-        instance.program.emit(sourceFile, writeFile, /*cancellationToken*/ undefined, /*emitOnlyDtsFiles*/ false, instance.transformers);
+        const sourceFile = program.getSourceFile(filePath);
+        program.emit(sourceFile, writeFile, /*cancellationToken*/ undefined, /*emitOnlyDtsFiles*/ false, instance.transformers);
         return outputFiles;
     }
     else {

src/servicesHost.ts

@@ -179,7 +179,7 @@ export function makeWatchHost(
         useCaseSensitiveFileNames: () => compiler.sys.useCaseSensitiveFileNames,
         getNewLine: () => newLine,
         getCurrentDirectory,
-        getDefaultLibFileName,
+        getDefaultLibFileName: options => compiler.getDefaultLibFilePath(options),
 
         fileExists,
         readFile: readFileWithCachingText,
@@ -209,10 +209,6 @@ export function makeWatchHost(
     };
     return watchHost;
 
-    function getDefaultLibFileName(options: typescript.CompilerOptions) {
-        return path.join(path.dirname(compiler.sys.getExecutingFilePath()), compiler.getDefaultLibFileName(options));
-    }
-
     function getRootFileNames() {
         return Object.keys(files).filter(filePath => filePath.match(scriptRegex));
     }