fix(eslint-plugin): [no-use-before-define] correctly handle typeof type references (typescript-eslint#2623)

Drakota · web-flow · commit 8e44c78a2041 · 2020-10-11T16:38:35.000-07:00
diff --git a/packages/eslint-plugin/src/rules/no-use-before-define.ts b/packages/eslint-plugin/src/rules/no-use-before-define.ts
@@ -92,6 +92,37 @@ function isOuterVariable(
   );
 }
 
+/**
+ * Recursively checks whether or not a given reference has a type query declaration among it's parents
+ */
+function referenceContainsTypeQuery(node: TSESTree.Node): boolean {
+  switch (node.type) {
+    case AST_NODE_TYPES.TSTypeQuery:
+      return true;
+
+    case AST_NODE_TYPES.TSQualifiedName:
+    case AST_NODE_TYPES.Identifier:
+      if (!node.parent) {
+        return false;
+      }
+      return referenceContainsTypeQuery(node.parent);
+
+    default:
+      // if we find a different node, there's no chance that we're in a TSTypeQuery
+      return false;
+  }
+}
+
+/**
+ * Checks whether or not a given reference is a type reference.
+ */
+function isTypeReference(reference: TSESLint.Scope.Reference): boolean {
+  return (
+    reference.isTypeReference ||
+    referenceContainsTypeQuery(reference.identifier)
+  );
+}
+
 /**
  * Checks whether or not a given location is inside of the range of a given node.
  */
@@ -219,7 +250,7 @@ export default util.createRule<Options, MessageIds>({
       variable: TSESLint.Scope.Variable,
       reference: TSESLint.Scope.Reference,
     ): boolean {
-      if (reference.isTypeReference && options.ignoreTypeReferences) {
+      if (options.ignoreTypeReferences && isTypeReference(reference)) {
         return false;
       }
       if (isFunction(variable)) {
diff --git a/packages/eslint-plugin/tests/rules/no-use-before-define.test.ts b/packages/eslint-plugin/tests/rules/no-use-before-define.test.ts
@@ -219,7 +219,43 @@ type Foo = string | number;
       `,
       options: [{ typedefs: false }],
     },
+    // https://github.com/typescript-eslint/typescript-eslint/issues/2572
+    {
+      code: `
+interface Bar {
+  type: typeof Foo;
+}
+
+const Foo = 2;
+      `,
+      options: [{ ignoreTypeReferences: true }],
+    },
+    {
+      code: `
+interface Bar {
+  type: typeof Foo.FOO;
+}
+
+class Foo {
+  public static readonly FOO = '';
+}
+      `,
+      options: [{ ignoreTypeReferences: true }],
+    },
+    {
+      code: `
+interface Bar {
+  type: typeof Foo.Bar.Baz;
+}
 
+const Foo = {
+  Bar: {
+    Baz: 1,
+  },
+};
+      `,
+      options: [{ ignoreTypeReferences: true }],
+    },
     // https://github.com/bradzacher/eslint-plugin-typescript/issues/141
     {
       code: `
@@ -875,6 +911,65 @@ for (var a of a) {
       ],
     },
 
+    // "ignoreTypeReferences" option
+    {
+      code: `
+interface Bar {
+  type: typeof Foo;
+}
+
+const Foo = 2;
+      `,
+      options: [{ ignoreTypeReferences: false }],
+      errors: [
+        {
+          messageId: 'noUseBeforeDefine',
+          data: { name: 'Foo' },
+          type: AST_NODE_TYPES.Identifier,
+        },
+      ],
+    },
+    {
+      code: `
+interface Bar {
+  type: typeof Foo.FOO;
+}
+
+class Foo {
+  public static readonly FOO = '';
+}
+      `,
+      options: [{ ignoreTypeReferences: false }],
+      errors: [
+        {
+          messageId: 'noUseBeforeDefine',
+          data: { name: 'Foo' },
+          type: AST_NODE_TYPES.Identifier,
+        },
+      ],
+    },
+    {
+      code: `
+interface Bar {
+  type: typeof Foo.Bar.Baz;
+}
+
+const Foo = {
+  Bar: {
+    Baz: 1,
+  },
+};
+      `,
+      options: [{ ignoreTypeReferences: false }],
+      errors: [
+        {
+          messageId: 'noUseBeforeDefine',
+          data: { name: 'Foo' },
+          type: AST_NODE_TYPES.Identifier,
+        },
+      ],
+    },
+
     // "variables" option
     {
       code: `
