fix(ivy): emit fs-relative paths when rootDir(s) aren't in effect (#33828)

Previously, the compiler assumed that all TS files logically within a
project existed under one or more "root directories". If the TS compiler
option `rootDir` or `rootDirs` was set, they would dictate the root
directories in use, otherwise the current directory was used.

Unfortunately this assumption was unfounded - it's common for projects
without explicit `rootDirs` to import from files outside the current
working directory. In such cases the `LogicalProjectStrategy` would attempt
to generate imports into those files, and fail. This would lead to no
`ReferenceEmitStrategy` being able to generate an import, and end in a
compiler assertion failure.

This commit introduces a new strategy to use when there are no `rootDirs`
explicitly present, the `RelativePathStrategy`. It uses simpler, filesystem-
relative paths to generate imports, even to files above the current working
directory.

Fixes #33659
Fixes #33562

PR Close #33828

packages/compiler-cli/test/ngtsc/monorepo_spec.ts

@@ -0,0 +1,117 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
+import {absoluteFrom} from '../../src/ngtsc/file_system';
+import {runInEachFileSystem} from '../../src/ngtsc/file_system/testing';
+import {loadStandardTestFiles} from '../helpers/src/mock_file_loading';
+
+import {NgtscTestEnvironment} from './env';
+
+const testFiles = loadStandardTestFiles();
+
+runInEachFileSystem(() => {
+  describe('monorepos', () => {
+    let env !: NgtscTestEnvironment;
+
+    beforeEach(() => {
+      env = NgtscTestEnvironment.setup(testFiles, absoluteFrom('/app'));
+      env.tsconfig();
+
+      // env.tsconfig() will write to /app/tsconfig.json, but list it as extending
+      // ./tsconfig-base.json. So that file should exist, and redirect to ../tsconfig-base.json.
+      env.write('/app/tsconfig-base.json', JSON.stringify({'extends': '../tsconfig-base.json'}));
+    });
+
+    it('should compile a project with a reference above the current dir', () => {
+      env.write('/app/index.ts', `
+        import {Component, NgModule} from '@angular/core';
+        import {LibModule} from '../lib/module';
+
+        @Component({
+          selector: 'app-cmp',
+          template: '<lib-cmp></lib-cmp>',
+        })
+        export class AppCmp {}
+
+        @NgModule({
+          declarations: [AppCmp],
+          imports: [LibModule],
+        })
+        export class AppModule {}
+      `);
+      env.write('/lib/module.ts', `
+        import {NgModule} from '@angular/core';
+        import {LibCmp} from './cmp';
+
+        @NgModule({
+          declarations: [LibCmp],
+          exports: [LibCmp],
+        })
+        export class LibModule {}
+      `);
+      env.write('/lib/cmp.ts', `
+        import {Component} from '@angular/core';
+
+        @Component({
+          selector: 'lib-cmp',
+          template: '...',
+        })
+        export class LibCmp {}
+      `);
+
+      env.driveMain();
+
+      const jsContents = env.getContents('app/index.js');
+      expect(jsContents).toContain(`import * as i1 from "../lib/cmp";`);
+    });
+
+    it('should compile a project with a reference into the same dir', () => {
+      env.write('/app/index.ts', `
+        import {Component, NgModule} from '@angular/core';
+        import {TargetModule} from './target';
+
+        @Component({
+          selector: 'app-cmp',
+          template: '<target-cmp></target-cmp>',
+        })
+        export class AppCmp {}
+
+        @NgModule({
+          declarations: [AppCmp],
+          imports: [TargetModule],
+        })
+        export class AppModule {}
+      `);
+
+      env.write('/app/target.ts', `
+        import {Component, NgModule} from '@angular/core';
+
+        @Component({
+          selector: 'target-cmp',
+          template: '...',
+        })
+        export class TargetCmp {}
+
+        @NgModule({
+          declarations: [TargetCmp],
+          exports: [TargetCmp],
+        })
+        export class TargetModule {}
+      `);
+
+      env.driveMain();
+
+      // Look for index.js, not app/index.js, because of TypeScript's behavior of stripping off the
+      // common prefix of all input files.
+      const jsContents = env.getContents('index.js');
+
+      // The real goal of this test was to check that the relative import has the leading './'.
+      expect(jsContents).toContain(`import * as i1 from "./target";`);
+    });
+  });
+});