no-unbound-method: Skip past casts and parentheses (palantir#2838)

src/rules/noUnboundMethodRule.ts

@@ -87,6 +87,11 @@ function isSafeUse(node: ts.Node): boolean {
         // Allow most binary operators, but don't allow e.g. `myArray.forEach(obj.method || otherObj.otherMethod)`.
         case ts.SyntaxKind.BinaryExpression:
             return (parent as ts.BinaryExpression).operatorToken.kind !== ts.SyntaxKind.BarBarToken;
+        case ts.SyntaxKind.NonNullExpression:
+        case ts.SyntaxKind.AsExpression:
+        case ts.SyntaxKind.TypeAssertionExpression:
+        case ts.SyntaxKind.ParenthesizedExpression:
+            return isSafeUse(parent);
         // Allow use in conditions
         case ts.SyntaxKind.ConditionalExpression:
             return (parent as ts.ConditionalExpression).condition === node;

test/rules/no-unbound-method/default/test.ts.lint

@@ -0,0 +1,10 @@
+interface I { m?(): void; }
+function f(i: I) {
+    i.m!();
+    (i.m as any)(1);
+    (<any> i.m)(1);
+    return i.m!;
+           ~~~ [0]
+}
+
+[0]: Avoid referencing unbound methods which may cause unintentional scoping of 'this'.

test/rules/no-unbound-method/default/test.tsx.lint

@@ -34,7 +34,7 @@ c.method ? 1 : 2;
                ~~~~~~~~ [0]
 if (c.method) {}
 while (c.method) {}
-do () while (c.method);
+do {} while (c.method);
 for (c.method; c.method; c.method) {}