feat(router): add migration for ActivatedRouteSnapshot.fragment (angular#41092)

Adds a migration that casts the value of `ActivatedRouteSnapshot.fragment` to be non-nullable.

Also moves some code from the `AbstractControl.parent` migration so that it can be reused.

Relates to angular#37336.

PR Close angular#41092

Author: crisbeto

packages/core/schematics/BUILD.bazel

@@ -11,6 +11,7 @@ pkg_npm(
     visibility = ["//packages/core:__pkg__"],
     deps = [
         "//packages/core/schematics/migrations/abstract-control-parent",
+        "//packages/core/schematics/migrations/activated-route-snapshot-fragment",
         "//packages/core/schematics/migrations/can-activate-with-redirect-to",
         "//packages/core/schematics/migrations/dynamic-queries",
         "//packages/core/schematics/migrations/initial-navigation",

packages/core/schematics/migrations.json

@@ -84,6 +84,11 @@
       "version": "11.1.0-beta",
       "description": "Removes `canActivate` from a `Route` config when `redirectTo` is also present",
       "factory": "./migrations/can-activate-with-redirect-to/index"
+    },
+    "migration-v12-activated-route-snapshot-fragment": {
+      "version": "12.0.0-beta",
+      "description": "In Angular version 12, the type of ActivatedRouteSnapshot.fragment is nullable. This migration automatically adds non-null assertions to it.",
+      "factory": "./migrations/activated-route-snapshot-fragment/index"
     }
   }
-}
+}

packages/core/schematics/migrations/abstract-control-parent/util.ts

@@ -8,14 +8,11 @@
 
 import {normalize} from 'path';
 import * as ts from 'typescript';
+import {isNullCheck, isSafeAccess} from '../../utils/typescript/nodes';
+import {hasOneOfTypes, isNullableType} from '../../utils/typescript/symbol';
 
 /** Names of symbols from `@angular/forms` whose `parent` accesses have to be migrated. */
-const abstractControlSymbols = new Set<string>([
-  'AbstractControl',
-  'FormArray',
-  'FormControl',
-  'FormGroup',
-]);
+const abstractControlSymbols = ['AbstractControl', 'FormArray', 'FormControl', 'FormGroup'];
 
 /**
  * Finds the `PropertyAccessExpression`-s that are accessing the `parent` property in
@@ -38,78 +35,6 @@ export function findParentAccesses(
   return results;
 }
 
-/** Checks whether a node's type is nullable (`null`, `undefined` or `void`). */
-function isNullableType(typeChecker: ts.TypeChecker, node: ts.Node) {
-  // Skip expressions in the form of `foo.bar!.baz` since the `TypeChecker` seems
-  // to identify them as null, even though the user indicated that it won't be.
-  if (node.parent && ts.isNonNullExpression(node.parent)) {
-    return false;
-  }
-
-  const type = typeChecker.getTypeAtLocation(node);
-  const typeNode = typeChecker.typeToTypeNode(type, undefined, ts.NodeBuilderFlags.None);
-  let hasSeenNullableType = false;
-
-  // Trace the type of the node back to a type node, walk
-  // through all of its sub-nodes and look for nullable tyes.
-  if (typeNode) {
-    (function walk(current: ts.Node) {
-      if (current.kind === ts.SyntaxKind.NullKeyword ||
-          current.kind === ts.SyntaxKind.UndefinedKeyword ||
-          current.kind === ts.SyntaxKind.VoidKeyword) {
-        hasSeenNullableType = true;
-        // Note that we don't descend into type literals, because it may cause
-        // us to mis-identify the root type as nullable, because it has a nullable
-        // property (e.g. `{ foo: string | null }`).
-      } else if (!hasSeenNullableType && !ts.isTypeLiteralNode(current)) {
-        current.forEachChild(walk);
-      }
-    })(typeNode);
-  }
-
-  return hasSeenNullableType;
-}
-
-/**
- * Checks whether a particular node is part of a null check. E.g. given:
- * `control.parent ? control.parent.value : null` the null check would be `control.parent`.
- */
-function isNullCheck(node: ts.PropertyAccessExpression): boolean {
-  if (!node.parent) {
-    return false;
-  }
-
-  // `control.parent && control.parent.value` where `node` is `control.parent`.
-  if (ts.isBinaryExpression(node.parent) && node.parent.left === node) {
-    return true;
-  }
-
-  // `control.parent && control.parent.parent && control.parent.parent.value`
-  // where `node` is `control.parent`.
-  if (node.parent.parent && ts.isBinaryExpression(node.parent.parent) &&
-      node.parent.parent.left === node.parent) {
-    return true;
-  }
-
-  // `if (control.parent) {...}` where `node` is `control.parent`.
-  if (ts.isIfStatement(node.parent) && node.parent.expression === node) {
-    return true;
-  }
-
-  // `control.parent ? control.parent.value : null` where `node` is `control.parent`.
-  if (ts.isConditionalExpression(node.parent) && node.parent.condition === node) {
-    return true;
-  }
-
-  return false;
-}
-
-/** Checks whether a property access is safe (e.g. `foo.parent?.value`). */
-function isSafeAccess(node: ts.PropertyAccessExpression): boolean {
-  return node.parent != null && ts.isPropertyAccessExpression(node.parent) &&
-      node.parent.expression === node && node.parent.questionDotToken != null;
-}
-
 /** Checks whether a property access is on an `AbstractControl` coming from `@angular/forms`. */
 function isAbstractControlReference(
     typeChecker: ts.TypeChecker, node: ts.PropertyAccessExpression): boolean {
@@ -119,37 +44,14 @@ function isAbstractControlReference(
   // If such a node is found, we check whether the type is one of the `AbstractControl` symbols
   // and whether it comes from the `@angular/forms` directory in the `node_modules`.
   while (ts.isPropertyAccessExpression(current)) {
-    const type = typeChecker.getTypeAtLocation(current.expression);
-    const symbol = type.getSymbol();
-    if (symbol && type) {
+    const symbol = typeChecker.getTypeAtLocation(current.expression)?.getSymbol();
+    if (symbol) {
       const sourceFile = symbol.valueDeclaration?.getSourceFile();
       return sourceFile != null &&
           formsPattern.test(normalize(sourceFile.fileName).replace(/\\/g, '/')) &&
-          hasAbstractControlType(typeChecker, type);
+          hasOneOfTypes(typeChecker, current.expression, abstractControlSymbols);
     }
     current = current.expression;
   }
   return false;
 }
-
-/**
- * Walks through the sub-types of a type, looking for a type that
- * has the same name as one of the `AbstractControl` types.
- */
-function hasAbstractControlType(typeChecker: ts.TypeChecker, type: ts.Type): boolean {
-  const typeNode = typeChecker.typeToTypeNode(type, undefined, ts.NodeBuilderFlags.None);
-  let hasMatch = false;
-  if (typeNode) {
-    (function walk(current: ts.Node) {
-      if (ts.isIdentifier(current) && abstractControlSymbols.has(current.text)) {
-        hasMatch = true;
-        // Note that we don't descend into type literals, because it may cause
-        // us to mis-identify the root type as nullable, because it has a nullable
-        // property (e.g. `{ foo: FormControl }`).
-      } else if (!hasMatch && !ts.isTypeLiteralNode(current)) {
-        current.forEachChild(walk);
-      }
-    })(typeNode);
-  }
-  return hasMatch;
-}

packages/core/schematics/migrations/activated-route-snapshot-fragment/BUILD.bazel

@@ -0,0 +1,18 @@
+load("//tools:defaults.bzl", "ts_library")
+
+ts_library(
+    name = "activated-route-snapshot-fragment",
+    srcs = glob(["**/*.ts"]),
+    tsconfig = "//packages/core/schematics:tsconfig.json",
+    visibility = [
+        "//packages/core/schematics:__pkg__",
+        "//packages/core/schematics/migrations/google3:__pkg__",
+        "//packages/core/schematics/test:__pkg__",
+    ],
+    deps = [
+        "//packages/core/schematics/utils",
+        "@npm//@angular-devkit/schematics",
+        "@npm//@types/node",
+        "@npm//typescript",
+    ],
+)

packages/core/schematics/migrations/activated-route-snapshot-fragment/README.md

@@ -0,0 +1,34 @@
+## `ActivatedRouteSnapshot.fragment` migration
+
+The value if `ActivatedRouteSnapshot.fragment` is becoming nullable. This migration adds non-null
+assertions to it.
+
+#### Before
+```ts
+import { Component } from '@angular/core';
+import { ActivatedRouteSnapshot } from '@angular/router';
+
+@Component({})
+export class YourComponent {
+  private _activatedRouteSnapshot: ActivatedRouteSnapshot;
+
+  getFragmentValue() {
+    return this._activatedRouteSnapshot.fragment.value;
+  }
+}
+```
+
+#### After
+```ts
+import { Component } from '@angular/core';
+import { ActivatedRoute } from '@angular/router';
+
+@Component({})
+export class YourComponent {
+  private _activatedRouteSnapshot: ActivatedRouteSnapshot;
+
+  getFragmentValue() {
+    return this._activatedRouteSnapshot.fragment!.value;
+  }
+}
+```

packages/core/schematics/migrations/activated-route-snapshot-fragment/index.ts

@@ -0,0 +1,62 @@
+/**
+ * @license
+ * Copyright Google LLC 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 {Rule, SchematicsException, Tree} from '@angular-devkit/schematics';
+import {relative} from 'path';
+import * as ts from 'typescript';
+
+import {getProjectTsConfigPaths} from '../../utils/project_tsconfig_paths';
+import {canMigrateFile, createMigrationProgram} from '../../utils/typescript/compiler_host';
+import {findFragmentAccesses, migrateActivatedRouteSnapshotFragment} from './util';
+
+
+/**
+ * Migration that marks accesses of `ActivatedRouteSnapshot.fragment` as non-null.
+ */
+export default function(): Rule {
+  return (tree: Tree) => {
+    const {buildPaths, testPaths} = getProjectTsConfigPaths(tree);
+    const basePath = process.cwd();
+    const allPaths = [...buildPaths, ...testPaths];
+
+    if (!allPaths.length) {
+      throw new SchematicsException(
+          'Could not find any tsconfig file. Cannot migrate ' +
+          '`ActivatedRouteSnapshot.fragment` accesses.');
+    }
+
+    for (const tsconfigPath of allPaths) {
+      runActivatedRouteSnapshotFragmentMigration(tree, tsconfigPath, basePath);
+    }
+  };
+}
+
+function runActivatedRouteSnapshotFragmentMigration(
+    tree: Tree, tsconfigPath: string, basePath: string) {
+  const {program} = createMigrationProgram(tree, tsconfigPath, basePath);
+  const typeChecker = program.getTypeChecker();
+  const sourceFiles =
+      program.getSourceFiles().filter(sourceFile => canMigrateFile(basePath, sourceFile, program));
+  const printer = ts.createPrinter();
+
+  sourceFiles.forEach(sourceFile => {
+    const nodesToMigrate = findFragmentAccesses(typeChecker, sourceFile);
+
+    if (nodesToMigrate.size > 0) {
+      const update = tree.beginUpdate(relative(basePath, sourceFile.fileName));
+      nodesToMigrate.forEach(node => {
+        update.remove(node.getStart(), node.getWidth());
+        update.insertRight(
+            node.getStart(),
+            printer.printNode(
+                ts.EmitHint.Unspecified, migrateActivatedRouteSnapshotFragment(node), sourceFile));
+      });
+      tree.commitUpdate(update);
+    }
+  });
+}

packages/core/schematics/migrations/activated-route-snapshot-fragment/util.ts

@@ -0,0 +1,39 @@
+/**
+ * @license
+ * Copyright Google LLC 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 * as ts from 'typescript';
+import {isNullCheck, isSafeAccess} from '../../utils/typescript/nodes';
+import {hasOneOfTypes, isNullableType} from '../../utils/typescript/symbol';
+
+/**
+ * Finds all the accesses of `ActivatedRouteSnapshot.fragment`
+ * that need to be migrated within a particular file.
+ */
+export function findFragmentAccesses(
+    typeChecker: ts.TypeChecker, sourceFile: ts.SourceFile): Set<ts.PropertyAccessExpression> {
+  const results = new Set<ts.PropertyAccessExpression>();
+
+  sourceFile.forEachChild(function walk(node: ts.Node) {
+    if (ts.isPropertyAccessExpression(node) && node.name.text === 'fragment' &&
+        !results.has(node) && !isNullCheck(node) && !isSafeAccess(node) &&
+        hasOneOfTypes(typeChecker, node.expression, ['ActivatedRouteSnapshot']) &&
+        isNullableType(typeChecker, node)) {
+      results.add(node);
+    }
+
+    node.forEachChild(walk);
+  });
+
+  return results;
+}
+
+/** Migrates an `ActivatedRouteSnapshot.fragment` access. */
+export function migrateActivatedRouteSnapshotFragment(node: ts.PropertyAccessExpression): ts.Node {
+  // Turns `foo.fragment` into `foo.fragment!`.
+  return ts.createNonNullExpression(node);
+}

packages/core/schematics/migrations/google3/BUILD.bazel

@@ -6,6 +6,7 @@ ts_library(
     tsconfig = "//packages/core/schematics:tsconfig.json",
     visibility = ["//packages/core/schematics/test/google3:__pkg__"],
     deps = [
+        "//packages/core/schematics/migrations/activated-route-snapshot-fragment",
         "//packages/core/schematics/migrations/can-activate-with-redirect-to",
         "//packages/core/schematics/migrations/dynamic-queries",
         "//packages/core/schematics/migrations/initial-navigation",

packages/core/schematics/migrations/google3/activatedRouteSnapshotFragmentRule.ts

@@ -0,0 +1,40 @@
+/**
+ * @license
+ * Copyright Google LLC 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 {Replacement, RuleFailure, Rules} from 'tslint';
+import * as ts from 'typescript';
+
+import {findFragmentAccesses, migrateActivatedRouteSnapshotFragment} from '../activated-route-snapshot-fragment/util';
+
+export class Rule extends Rules.TypedRule {
+  applyWithProgram(sourceFile: ts.SourceFile, program: ts.Program): RuleFailure[] {
+    if (sourceFile.isDeclarationFile || program.isSourceFileFromExternalLibrary(sourceFile)) {
+      return [];
+    }
+
+    const failures: RuleFailure[] = [];
+    const typeChecker = program.getTypeChecker();
+    const nodesToMigrate = findFragmentAccesses(typeChecker, sourceFile);
+
+    if (nodesToMigrate.size > 0) {
+      const printer = ts.createPrinter();
+      nodesToMigrate.forEach(node => {
+        const sourceFile = node.getSourceFile();
+        const migratedNode = migrateActivatedRouteSnapshotFragment(node);
+        const replacement = new Replacement(
+            node.getStart(), node.getWidth(),
+            printer.printNode(ts.EmitHint.Unspecified, migratedNode, sourceFile));
+        failures.push(new RuleFailure(
+            sourceFile, node.getStart(), node.getEnd(),
+            '`ActivatedRouteSnapshot.fragment` is nullable.', this.ruleName, replacement));
+      });
+    }
+
+    return failures;
+  }
+}

packages/core/schematics/test/BUILD.bazel

@@ -9,6 +9,7 @@ ts_library(
     ],
     deps = [
         "//packages/core/schematics/migrations/abstract-control-parent",
+        "//packages/core/schematics/migrations/activated-route-snapshot-fragment",
         "//packages/core/schematics/migrations/can-activate-with-redirect-to",
         "//packages/core/schematics/migrations/dynamic-queries",
         "//packages/core/schematics/migrations/initial-navigation",