build: add lint rule to enforce coercion static properties for setters

Adds a custom tslint rule to enforce that properties which use coercion in a setter also declare a static property to indicate the accepted types to ngtsc. Also handles inherited setters and properties coming from an interface being implemented (necessary to support mixins).

Relates to angular#17528.

tools/tslint-rules/coercionTypesRule.ts

@@ -0,0 +1,157 @@
+import * as ts from 'typescript';
+import * as Lint from 'tslint';
+import * as tsutils from 'tsutils';
+
+/**
+ * TSLint rule that verifies that classes declare corresponding `ngAcceptInputType_*`
+ * static fields for inputs that use coercion inside of their setters. Also handles
+ * inherited class members and members that come from an interface.
+ */
+export class Rule extends Lint.Rules.TypedRule {
+  applyWithProgram(sourceFile: ts.SourceFile, program: ts.Program): Lint.RuleFailure[] {
+    const walker = new Walker(sourceFile, this.getOptions(), program.getTypeChecker());
+    return this.applyWithWalker(walker);
+  }
+}
+
+class Walker extends Lint.RuleWalker {
+  /** Names of the coercion functions that we should be looking for. */
+  private _coercionFunctions: Set<string>;
+
+  /** Mapping of interfaces known to have coercion properties and the property names themselves. */
+  private _coercionInterfaces: {[interfaceName: string]: string[]};
+
+  constructor(sourceFile: ts.SourceFile,
+              options: Lint.IOptions,
+              private _typeChecker: ts.TypeChecker) {
+    super(sourceFile, options);
+    this._coercionFunctions = new Set(options.ruleArguments[0] || []);
+    this._coercionInterfaces = options.ruleArguments[1] || {};
+  }
+
+  visitClassDeclaration(node: ts.ClassDeclaration) {
+    this._lintClass(node, node);
+    this._lintInheritedProperties(node);
+    this._lintInterfaces(node);
+    super.visitClassDeclaration(node);
+  }
+
+  /**
+   * Goes thrown the own setters of a class declaration and checks whether they use coercion.
+   * @param node Class declaration to be checked.
+   * @param sourceClass Class declaration on which to look for static properties that declare the
+   *    accepted values for the setter.
+   */
+  private _lintClass(node: ts.ClassDeclaration, sourceClass: ts.ClassDeclaration): void {
+    node.members.forEach(member => {
+      if (ts.isSetAccessor(member) && usesCoercion(member, this._coercionFunctions)) {
+        this._checkForStaticMember(sourceClass, member.name.getText());
+      }
+    });
+  }
+
+  /**
+   * Goes up the inheritance chain of a class declaration and
+   * checks whether it has any setters using coercion.
+   * @param node Class declaration to be checked.
+   */
+  private _lintInheritedProperties(node: ts.ClassDeclaration): void {
+    let currentClass: ts.ClassDeclaration|null = node;
+
+    while (currentClass) {
+      const baseType = getBaseTypeIdentifier(currentClass);
+
+      if (!baseType) {
+        break;
+      }
+
+      const symbol = this._typeChecker.getTypeAtLocation(baseType).getSymbol();
+      currentClass = symbol && ts.isClassDeclaration(symbol.valueDeclaration) ?
+          symbol.valueDeclaration : null;
+
+      if (currentClass) {
+        this._lintClass(currentClass, node);
+      }
+    }
+  }
+
+  /**
+   * Checks whether the interfaces that a class implements contain any known coerced properties.
+   * @param node Class declaration to be checked.
+   */
+  private _lintInterfaces(node: ts.ClassDeclaration): void {
+    if (!node.heritageClauses) {
+      return;
+    }
+
+    node.heritageClauses.forEach(clause => {
+      if (clause.token === ts.SyntaxKind.ImplementsKeyword) {
+        clause.types.forEach(clauseType => {
+          if (ts.isIdentifier(clauseType.expression)) {
+            const propNames = this._coercionInterfaces[clauseType.expression.text];
+
+            if (propNames) {
+              propNames.forEach(propName => this._checkForStaticMember(node, propName));
+            }
+          }
+        });
+      }
+    });
+  }
+
+  /**
+   * Checks whether a class declaration has a static member, corresponding
+   * to the specified setter name, and logs a failure if it doesn't.
+   * @param node
+   * @param setterName
+   */
+  private _checkForStaticMember(node: ts.ClassDeclaration, setterName: string) {
+    const coercionPropertyName = `ngAcceptInputType_${setterName}`;
+    const correspondingCoercionProperty = node.members.find(member => {
+      return ts.isPropertyDeclaration(member) &&
+             tsutils.hasModifier(member.modifiers, ts.SyntaxKind.StaticKeyword) &&
+             member.name.getText() === coercionPropertyName;
+    });
+
+    if (!correspondingCoercionProperty) {
+      this.addFailureAtNode(node.name || node, `Class must declare static coercion ` +
+                                               `property called ${coercionPropertyName}.`);
+    }
+  }
+}
+
+/**
+ * Checks whether a setter uses coercion.
+ * @param setter Setter node that should be checked.
+ * @param coercionFunctions Names of the coercion functions that we should be looking for.
+ */
+function usesCoercion(setter: ts.SetAccessorDeclaration, coercionFunctions: Set<string>): boolean {
+  let coercionWasUsed = false;
+
+  setter.forEachChild(function walk(node: ts.Node) {
+    if (ts.isCallExpression(node) && ts.isIdentifier(node.expression) &&
+        coercionFunctions.has(node.expression.text)) {
+      coercionWasUsed = true;
+    }
+
+    if (!coercionWasUsed) {
+      node.forEachChild(walk);
+    }
+  });
+
+  return coercionWasUsed;
+}
+
+/** Gets the identifier node of the base type that a class is extending. */
+function getBaseTypeIdentifier(node: ts.ClassDeclaration): ts.Identifier|null {
+  if (node.heritageClauses) {
+    for (let clause of node.heritageClauses) {
+      if (clause.token === ts.SyntaxKind.ExtendsKeyword && clause.types.length &&
+          ts.isIdentifier(clause.types[0].expression)) {
+        return clause.types[0].expression;
+      }
+    }
+  }
+
+  return null;
+}

tslint.json

@@ -109,6 +109,13 @@
     "rxjs-imports": true,
     "require-breaking-change-version": true,
     "class-list-signatures": true,
+    "coercion-types": [false, // Disabled until #17528 gets in.
+      ["coerceBooleanProperty", "coerceCssPixelValue", "coerceNumberProperty"],
+      {
+        "CanDisable": ["disabled"],
+        "CanDisableRipple": ["disableRipple"]
+      }
+    ],
     "no-host-decorator-in-concrete": [
       true,
       "HostBinding",