[Fix] no-unused-prop-types: fix issue with propTypes misclassifying…

… props

lib/util/propTypes.js

@@ -67,6 +67,24 @@ function iterateProperties(context, properties, fn) {
   }
 }
 
+/**
+ * Checks if a node is inside a class property.
+ *
+ * @param {ASTNode} node  the AST node being checked.
+ * @returns {Boolean} True if the node has a ClassProperty ancestor, false if not.
+ */
+function isInsideClassProperty(node) {
+  let parent = node.parent;
+  while (parent) {
+    if (parent.type === 'ClassProperty') {
+      return true;
+    }
+    parent = parent.parent;
+  }
+
+  return false;
+}
+
 module.exports = function propTypesInstructions(context, components, utils) {
   // Used to track the type annotations in scope.
   // Necessary because babel's scopes do not track type annotations.
@@ -554,6 +572,10 @@ module.exports = function propTypesInstructions(context, components, utils) {
       return;
     }
 
+    if (isInsideClassProperty(node)) {
+      return;
+    }
+
     const param = node.params[0];
     if (param.typeAnnotation && param.typeAnnotation.typeAnnotation && param.typeAnnotation.typeAnnotation.type === 'UnionTypeAnnotation') {
       param.typeAnnotation.typeAnnotation.types.forEach(annotation => {

tests/lib/rules/no-unused-prop-types.js

@@ -2929,6 +2929,21 @@ ruleTester.run('no-unused-prop-types', rule, {
         '  })',
         '};'
       ].join('\n')
+    }, {
+      code: `
+        type Props = {
+          used: string,
+        }
+        class Hello extends React.Component<Props> {
+          renderHelper = ({unused}: {unused: string}) => {
+            return <div />;
+          }
+          render() {
+            return <div>{this.props.used}</div>;
+          }
+        }
+      `,
+      parser: 'babel-eslint'
     }
   ],