fix(ngcc): do not crash on overlapping entry-points (#36083)

When two entry-points overlap, ngcc may attempt to process some
files twice. Previously, when this occured ngcc would just exit with an
error preventing any other entry-points from being processed.

This commit changes ngcc so that if `errorOnFailedEntryPoint` is false, it will
simply log an error and continue to process entry-points. This is useful when
ngcc is processing the entire node_modules folder and there are some invalid
entry-points that the project doesn't actually use.

PR Close #36083

packages/compiler-cli/ngcc/src/main.ts

@@ -277,7 +277,8 @@ export function mainNgcc({basePath, targetEntryPointPath,
 
   // The function for creating the `compile()` function.
   const createCompileFn: CreateCompileFn = onTaskCompleted => {
-    const fileWriter = getFileWriter(fileSystem, pkgJsonUpdater, createNewEntryPointFormats);
+    const fileWriter = getFileWriter(
+        fileSystem, logger, pkgJsonUpdater, createNewEntryPointFormats, errorOnFailedEntryPoint);
     const transformer = new Transformer(fileSystem, logger);
 
     return (task: Task) => {
@@ -362,10 +363,11 @@ function getPackageJsonUpdater(inParallel: boolean, fs: FileSystem): PackageJson
 }
 
 function getFileWriter(
-    fs: FileSystem, pkgJsonUpdater: PackageJsonUpdater,
-    createNewEntryPointFormats: boolean): FileWriter {
-  return createNewEntryPointFormats ? new NewEntryPointFileWriter(fs, pkgJsonUpdater) :
-                                      new InPlaceFileWriter(fs);
+    fs: FileSystem, logger: Logger, pkgJsonUpdater: PackageJsonUpdater,
+    createNewEntryPointFormats: boolean, errorOnFailedEntryPoint: boolean): FileWriter {
+  return createNewEntryPointFormats ?
+      new NewEntryPointFileWriter(fs, logger, errorOnFailedEntryPoint, pkgJsonUpdater) :
+      new InPlaceFileWriter(fs, logger, errorOnFailedEntryPoint);
 }
 
 function getTaskQueue(

packages/compiler-cli/ngcc/src/writing/in_place_file_writer.ts

@@ -1,4 +1,3 @@
-
 /**
  * @license
  * Copyright Google Inc. All Rights Reserved.
@@ -7,6 +6,7 @@
  * found in the LICENSE file at https://angular.io/license
  */
 import {FileSystem, absoluteFrom, dirname} from '../../../src/ngtsc/file_system';
+import {Logger} from '../logging/logger';
 import {EntryPointJsonProperty} from '../packages/entry_point';
 import {EntryPointBundle} from '../packages/entry_point_bundle';
 import {FileToWrite} from '../rendering/utils';
@@ -18,7 +18,9 @@ export const NGCC_BACKUP_EXTENSION = '.__ivy_ngcc_bak';
  * a back-up of the original file with an extra `.__ivy_ngcc_bak` extension.
  */
 export class InPlaceFileWriter implements FileWriter {
-  constructor(protected fs: FileSystem) {}
+  constructor(
+      protected fs: FileSystem, protected logger: Logger,
+      protected errorOnFailedEntryPoint: boolean) {}
 
   writeBundle(
       _bundle: EntryPointBundle, transformedFiles: FileToWrite[],
@@ -30,12 +32,20 @@ export class InPlaceFileWriter implements FileWriter {
     this.fs.ensureDir(dirname(file.path));
     const backPath = absoluteFrom(`${file.path}${NGCC_BACKUP_EXTENSION}`);
     if (this.fs.exists(backPath)) {
-      throw new Error(
-          `Tried to overwrite ${backPath} with an ngcc back up file, which is disallowed.`);
+      if (this.errorOnFailedEntryPoint) {
+        throw new Error(
+            `Tried to overwrite ${backPath} with an ngcc back up file, which is disallowed.`);
+      } else {
+        this.logger.error(
+            `Tried to write ${backPath} with an ngcc back up file but it already exists so not writing, nor backing up, ${file.path}.\n` +
+            `This error may be because two or more entry-points overlap and ngcc has been asked to process some files more than once.\n` +
+            `You should check other entry-points in this package and set up a config to ignore any that you are not using.`);
+      }
+    } else {
+      if (this.fs.exists(file.path)) {
+        this.fs.moveFile(file.path, backPath);
+      }
+      this.fs.writeFile(file.path, file.contents);
     }
-    if (this.fs.exists(file.path)) {
-      this.fs.moveFile(file.path, backPath);
-    }
-    this.fs.writeFile(file.path, file.contents);
   }
 }

packages/compiler-cli/ngcc/src/writing/new_entry_point_file_writer.ts

@@ -8,6 +8,7 @@
  */
 import {AbsoluteFsPath, FileSystem, absoluteFromSourceFile, dirname, join, relative} from '../../../src/ngtsc/file_system';
 import {isDtsPath} from '../../../src/ngtsc/util/src/typescript';
+import {Logger} from '../logging/logger';
 import {EntryPoint, EntryPointJsonProperty} from '../packages/entry_point';
 import {EntryPointBundle} from '../packages/entry_point_bundle';
 import {FileToWrite} from '../rendering/utils';
@@ -27,7 +28,11 @@ export const NGCC_PROPERTY_EXTENSION = '_ivy_ngcc';
  * `InPlaceFileWriter`).
  */
 export class NewEntryPointFileWriter extends InPlaceFileWriter {
-  constructor(fs: FileSystem, private pkgJsonUpdater: PackageJsonUpdater) { super(fs); }
+  constructor(
+      fs: FileSystem, logger: Logger, errorOnFailedEntryPoint: boolean,
+      private pkgJsonUpdater: PackageJsonUpdater) {
+    super(fs, logger, errorOnFailedEntryPoint);
+  }
 
   writeBundle(
       bundle: EntryPointBundle, transformedFiles: FileToWrite[],