chore(lint): re-enable linter and fix violations

fixes #7798

gulpfile.js

@@ -329,17 +329,7 @@ gulp.task('lint', ['build.tools'], function() {
   var tslint = require('gulp-tslint');
   // Built-in rules are at
   // https://github.com/palantir/tslint#supported-rules
-  var tslintConfig = {
-    "rules": {
-      "requireInternalWithUnderscore": true,
-      "requireParameterType": true,
-      "requireReturnType": true,
-      "semicolon": true,
-
-      // TODO: find a way to just screen for reserved names
-      "variable-name": false
-    }
-  };
+  var tslintConfig = require('./tslint.json');
   return gulp.src(['modules/angular2/src/**/*.ts', '!modules/angular2/src/testing/**'])
       .pipe(tslint({
         tslint: require('tslint').default,

tools/tslint/duplicateModuleImportRule.ts

@@ -0,0 +1,49 @@
+import {RuleFailure} from 'tslint/lib/lint';
+import {AbstractRule} from 'tslint/lib/rules';
+import {RuleWalker} from 'tslint/lib/language/walker';
+import * as ts from 'typescript';
+
+export class Rule extends AbstractRule {
+  public static FAILURE_STRING = "duplicate module import";
+
+  public apply(sourceFile: ts.SourceFile): RuleFailure[] {
+    const typedefWalker = new ModuleImportWalker(sourceFile, this.getOptions());
+    return this.applyWithWalker(typedefWalker);
+  }
+}
+
+class ModuleImportWalker extends RuleWalker {
+  importModulesSeen: string[] = [];
+
+  protected visitImportDeclaration(node: ts.ImportDeclaration): void {
+    this.visitModuleSpecifier(node.moduleSpecifier);
+    super.visitImportDeclaration(node);
+  }
+
+  protected visitImportEqualsDeclaration(node: ts.ImportEqualsDeclaration): void {
+    this.visitModuleSpecifier(node.moduleReference);
+    super.visitImportEqualsDeclaration(node);
+  }
+
+  private checkTypeAnnotation(location: number, typeAnnotation: ts.TypeNode, name?: ts.Node) {
+    if (typeAnnotation == null) {
+      let ns = "<name missing>";
+      if (name != null && name.kind === ts.SyntaxKind.Identifier) {
+        ns = (<ts.Identifier>name).text;
+      }
+      if (ns.charAt(0) === '_') return;
+      let failure = this.createFailure(location, 1, "expected parameter " + ns + " to have a type");
+      this.addFailure(failure);
+    }
+  }
+
+  private visitModuleSpecifier(moduleSpecifier: ts.Node) {
+    var text = moduleSpecifier.getText();
+    if (this.importModulesSeen.indexOf(text) >= 0) {
+      let failure =
+          this.createFailure(moduleSpecifier.getEnd(), 1, "Duplicate imports from module " + text);
+      this.addFailure(failure);
+    }
+    this.importModulesSeen.push(text);
+  }
+}

tslint.json

@@ -0,0 +1,10 @@
+{
+    "rules": {
+      "requireInternalWithUnderscore": true,
+      "requireParameterType": true,
+      "requireReturnType": true,
+      "duplicateModuleImport": false,
+      "semicolon": true,
+      "variable-name": false
+    }
+}