Revert "refactor(compiler): refactor and export Bazel host creation. (#34686)" (#35063)

This reverts commit cb142b6df9fa3b43e6905358c880c11f6a9abb45.

The intention of this commit was for a consumer of the `compile` function to
pass the `bazelHost` it returns into future invocations, reusing the
`FileCache` between them. However, first-party ngc_wrapped does not do this,
which caused a performance regression as the `FileCache` was no longer
shared between compilations.

PR Close #35063

packages/bazel/src/ngc-wrapped/index.ts

@@ -7,7 +7,7 @@
  */
 
 import * as ng from '@angular/compiler-cli';
-import {BazelOptions, CachedFileLoader, CompilerHost as BazelHost, FileCache, FileLoader, UncachedFileLoader, constructManifest, debug, parseTsconfig, resolveNormalizedPath, runAsWorker, runWorkerLoop} from '@bazel/typescript';
+import {BazelOptions, CachedFileLoader, CompilerHost, FileCache, FileLoader, UncachedFileLoader, constructManifest, debug, parseTsconfig, resolveNormalizedPath, runAsWorker, runWorkerLoop} from '@bazel/typescript';
 import * as fs from 'fs';
 import * as path from 'path';
 import * as tsickle from 'tsickle';
@@ -35,6 +35,9 @@ export function main(args) {
   return 0;
 }
 
+/** The one FileCache instance used in this process. */
+const fileCache = new FileCache<ts.SourceFile>(debug);
+
 export function runOneBuild(args: string[], inputs?: {[path: string]: string}): boolean {
   if (args[0] === '-p') args.shift();
   // Strip leading at-signs, used to indicate a params file
@@ -141,10 +144,8 @@ export function relativeToRootDirs(filePath: string, rootDirs: string[]): string
   return filePath;
 }
 
-export function compile({
+export function compile({allDepsCompiledWithBazel = true, compilerOpts, tsHost, bazelOpts, files,
-    allDepsCompiledWithBazel = true, compilerOpts, tsHost, bazelOpts, files, inputs, expectedOuts,
+                         inputs, expectedOuts, gatherDiagnostics, bazelHost}: {
-    gatherDiagnostics, bazelHost,
-}: {
   allDepsCompiledWithBazel?: boolean,
   compilerOpts: ng.CompilerOptions,
   tsHost: ts.CompilerHost, inputs?: {[path: string]: string},
@@ -152,15 +153,41 @@ export function compile({
   files: string[],
   expectedOuts: string[],
   gatherDiagnostics?: (program: ng.Program) => ng.Diagnostics,
-  bazelHost?: BazelHost,
+  bazelHost?: CompilerHost,
 }): {diagnostics: ng.Diagnostics, program: ng.Program} {
+  let fileLoader: FileLoader;
+
+  if (bazelOpts.maxCacheSizeMb !== undefined) {
+    const maxCacheSizeBytes = bazelOpts.maxCacheSizeMb * (1 << 20);
+    fileCache.setMaxCacheSize(maxCacheSizeBytes);
+  } else {
+    fileCache.resetMaxCacheSize();
+  }
+
+  if (inputs) {
+    fileLoader = new CachedFileLoader(fileCache);
+    // Resolve the inputs to absolute paths to match TypeScript internals
+    const resolvedInputs = new Map<string, string>();
+    const inputKeys = Object.keys(inputs);
+    for (let i = 0; i < inputKeys.length; i++) {
+      const key = inputKeys[i];
+      resolvedInputs.set(resolveNormalizedPath(key), inputs[key]);
+    }
+    fileCache.updateCache(resolvedInputs);
+  } else {
+    fileLoader = new UncachedFileLoader();
+  }
+
   if (!bazelOpts.es5Mode) {
     compilerOpts.annotateForClosureCompiler = true;
     compilerOpts.annotationsAs = 'static fields';
   }
 
+  // Detect from compilerOpts whether the entrypoint is being invoked in Ivy mode.
+  const isInIvyMode = compilerOpts.enableIvy === 'ngtsc';
+
   // Disable downleveling and Closure annotation if in Ivy mode.
-  if (compilerOpts.enableIvy) {
+  if (isInIvyMode) {
     compilerOpts.annotationsAs = 'decorators';
   }
 
@@ -185,14 +212,41 @@ export function compile({
         }
       };
 
+  // Patch fileExists when resolving modules, so that CompilerHost can ask TypeScript to
+  // resolve non-existing generated files that don't exist on disk, but are
+  // synthetic and added to the `programWithStubs` based on real inputs.
+  const generatedFileModuleResolverHost = Object.create(tsHost);
+  generatedFileModuleResolverHost.fileExists = (fileName: string) => {
+    const match = NGC_GEN_FILES.exec(fileName);
+    if (match) {
+      const [, file, suffix, ext] = match;
+      // Performance: skip looking for files other than .d.ts or .ts
+      if (ext !== '.ts' && ext !== '.d.ts') return false;
+      if (suffix.indexOf('ngstyle') >= 0) {
+        // Look for foo.css on disk
+        fileName = file;
+      } else {
+        // Look for foo.d.ts or foo.ts on disk
+        fileName = file + (ext || '');
+      }
+    }
+    return tsHost.fileExists(fileName);
+  };
+
+  function generatedFileModuleResolver(
+      moduleName: string, containingFile: string,
+      compilerOptions: ts.CompilerOptions): ts.ResolvedModuleWithFailedLookupLocations {
+    return ts.resolveModuleName(
+        moduleName, containingFile, compilerOptions, generatedFileModuleResolverHost);
+  }
+
   if (!bazelHost) {
-    const fileLoader = createFileLoader(inputs, bazelOpts);
+    bazelHost = new CompilerHost(
-    bazelHost = new BazelHost(
         files, compilerOpts, bazelOpts, tsHost, fileLoader, generatedFileModuleResolver);
   }
 
   // Also need to disable decorator downleveling in the BazelHost in Ivy mode.
-  if (compilerOpts.enableIvy) {
+  if (isInIvyMode) {
     bazelHost.transformDecorators = false;
   }
 
@@ -379,68 +433,6 @@ export function compile({
   return {program, diagnostics};
 }
 
-/** A module resolver for handling generated files in Bazel. */
-export function generatedFileModuleResolver(
-    moduleName: string, containingFile: string, compilerOptions: ts.CompilerOptions,
-    host: ts.ModuleResolutionHost, ): ts.ResolvedModuleWithFailedLookupLocations {
-  // Patch fileExists when resolving modules, so that CompilerHost can ask
-  // TypeScript to resolve non-existing generated files that don't exist on
-  // disk, but are synthetic and added to the `programWithStubs` based on real
-  // inputs.
-  const generatedFileModuleResolverHost = Object.assign({}, host, {
-    fileExists: (...[fileName, ...rest]: Parameters<typeof host.fileExists>):
-                    ReturnType<typeof host.fileExists> => {
-                      const match = NGC_GEN_FILES.exec(fileName);
-                      if (match) {
-                        const [, file, suffix, ext] = match;
-                        // Performance: skip looking for files other than .d.ts or .ts
-                        if (ext !== '.ts' && ext !== '.d.ts') return false;
-                        if (suffix.indexOf('ngstyle') >= 0) {
-                          // Look for foo.css on disk
-                          fileName = file;
-                        } else {
-                          // Look for foo.d.ts or foo.ts on disk
-                          fileName = file + (ext || '');
-                        }
-                      }
-
-                      return host.fileExists(fileName, ...rest);
-                    },
-  });
-
-  return ts.resolveModuleName(
-      moduleName, containingFile, compilerOptions, generatedFileModuleResolverHost);
-}
-
-/** Creates a {@link FileLoader} to cache Bazel inputs.*/
-export function createFileLoader(
-    inputs: {[key: string]: string} | undefined, bazelOpts: BazelOptions): FileLoader {
-  /** The one FileCache instance used in this process. */
-  const fileCache = new FileCache<ts.SourceFile>(debug);
-
-  if (bazelOpts.maxCacheSizeMb !== undefined) {
-    const maxCacheSizeBytes = bazelOpts.maxCacheSizeMb * (1 << 20);
-    fileCache.setMaxCacheSize(maxCacheSizeBytes);
-  } else {
-    fileCache.resetMaxCacheSize();
-  }
-
-  if (inputs) {
-    const fileLoader = new CachedFileLoader(fileCache);
-    // Resolve the inputs to absolute paths to match TypeScript internals
-    const resolvedInputs = new Map<string, string>();
-    const inputKeys = Object.keys(inputs);
-    for (let i = 0; i < inputKeys.length; i++) {
-      const key = inputKeys[i];
-      resolvedInputs.set(resolveNormalizedPath(key), inputs[key]);
-    }
-    fileCache.updateCache(resolvedInputs);
-    return fileLoader;
-  } else {
-    return new UncachedFileLoader();
-  }
-}
-
 /**
  * Generate metadata.json for the specified `files`. By default, metadata.json
  * is only generated by the compiler if --flatModuleOutFile is specified. But