[api-extractor] Fix an InternalError when a declaration refers to itself using "typeof"

apps/api-extractor/src/analyzer/ExportAnalyzer.ts

@@ -348,6 +348,17 @@ export class ExportAnalyzer {
     symbol: ts.Symbol,
     referringModuleIsExternal: boolean
   ): AstEntity | undefined {
+    // eslint-disable-next-line no-bitwise
+    if ((symbol.flags & ts.SymbolFlags.FunctionScopedVariable) !== 0) {
+      // If a symbol refers back to part of its own definition, don't follow that rabbit hole
+      // Example:
+      //
+      // function f(x: number): typeof x {
+      //    return 123;
+      // }
+      return undefined;
+    }
+
     let current: ts.Symbol = symbol;
 
     if (referringModuleIsExternal) {

build-tests/api-extractor-scenarios/config/build-config.json

@@ -31,6 +31,7 @@
     "preapproved",
     "typeOf",
     "typeOf2",
+    "typeOf3",
     "typeParameters"
   ]
 }

build-tests/api-extractor-scenarios/etc/test-outputs/typeOf3/api-extractor-scenarios.api.json

@@ -0,0 +1,153 @@
+{
+  "metadata": {
+    "toolPackage": "@microsoft/api-extractor",
+    "toolVersion": "[test mode]",
+    "schemaVersion": 1003,
+    "oldestForwardsCompatibleVersion": 1001
+  },
+  "kind": "Package",
+  "canonicalReference": "api-extractor-scenarios!",
+  "docComment": "",
+  "name": "api-extractor-scenarios",
+  "members": [
+    {
+      "kind": "EntryPoint",
+      "canonicalReference": "api-extractor-scenarios!",
+      "name": "",
+      "members": [
+        {
+          "kind": "Function",
+          "canonicalReference": "api-extractor-scenarios!f1:function(1)",
+          "docComment": "/**\n * A function that references its own parameter type.\n */\n",
+          "excerptTokens": [
+            {
+              "kind": "Content",
+              "text": "export declare function f1(x: "
+            },
+            {
+              "kind": "Content",
+              "text": "number"
+            },
+            {
+              "kind": "Content",
+              "text": "): "
+            },
+            {
+              "kind": "Content",
+              "text": "typeof "
+            },
+            {
+              "kind": "Reference",
+              "text": "x",
+              "canonicalReference": "api-extractor-scenarios!~x:var"
+            },
+            {
+              "kind": "Content",
+              "text": ";"
+            }
+          ],
+          "returnTypeTokenRange": {
+            "startIndex": 3,
+            "endIndex": 5
+          },
+          "releaseTag": "Public",
+          "overloadIndex": 1,
+          "parameters": [
+            {
+              "parameterName": "x",
+              "parameterTypeTokenRange": {
+                "startIndex": 1,
+                "endIndex": 2
+              }
+            }
+          ],
+          "name": "f1"
+        },
+        {
+          "kind": "Function",
+          "canonicalReference": "api-extractor-scenarios!f2:function(1)",
+          "docComment": "/**\n * A function that indirectly references its own parameter type.\n */\n",
+          "excerptTokens": [
+            {
+              "kind": "Content",
+              "text": "export declare function f2(x: "
+            },
+            {
+              "kind": "Content",
+              "text": "number"
+            },
+            {
+              "kind": "Content",
+              "text": "): "
+            },
+            {
+              "kind": "Content",
+              "text": "keyof typeof "
+            },
+            {
+              "kind": "Reference",
+              "text": "x",
+              "canonicalReference": "api-extractor-scenarios!~x:var"
+            },
+            {
+              "kind": "Content",
+              "text": ";"
+            }
+          ],
+          "returnTypeTokenRange": {
+            "startIndex": 3,
+            "endIndex": 5
+          },
+          "releaseTag": "Public",
+          "overloadIndex": 1,
+          "parameters": [
+            {
+              "parameterName": "x",
+              "parameterTypeTokenRange": {
+                "startIndex": 1,
+                "endIndex": 2
+              }
+            }
+          ],
+          "name": "f2"
+        },
+        {
+          "kind": "Function",
+          "canonicalReference": "api-extractor-scenarios!f3:function(1)",
+          "docComment": "/**\n * A function that references its own type.\n */\n",
+          "excerptTokens": [
+            {
+              "kind": "Content",
+              "text": "export declare function f3(): "
+            },
+            {
+              "kind": "Content",
+              "text": "typeof "
+            },
+            {
+              "kind": "Reference",
+              "text": "f3",
+              "canonicalReference": "api-extractor-scenarios!f3:function"
+            },
+            {
+              "kind": "Content",
+              "text": " | undefined"
+            },
+            {
+              "kind": "Content",
+              "text": ";"
+            }
+          ],
+          "returnTypeTokenRange": {
+            "startIndex": 1,
+            "endIndex": 4
+          },
+          "releaseTag": "Public",
+          "overloadIndex": 1,
+          "parameters": [],
+          "name": "f3"
+        }
+      ]
+    }
+  ]
+}

build-tests/api-extractor-scenarios/etc/test-outputs/typeOf3/api-extractor-scenarios.api.md

@@ -0,0 +1,19 @@
+## API Report File for "api-extractor-scenarios"
+
+> Do not edit this file. It is a report generated by [API Extractor](https://api-extractor.com/).
+
+```ts
+
+// @public
+export function f1(x: number): typeof x;
+
+// @public
+export function f2(x: number): keyof typeof x;
+
+// @public
+export function f3(): typeof f3 | undefined;
+
+
+// (No @packageDocumentation comment for this package)
+
+```

build-tests/api-extractor-scenarios/etc/test-outputs/typeOf3/rollup.d.ts

@@ -0,0 +1,17 @@
+
+/**
+ * A function that references its own parameter type.
+ */
+export declare function f1(x: number): typeof x;
+
+/**
+ * A function that indirectly references its own  parameter type.
+ */
+export declare function f2(x: number): keyof typeof x;
+
+/**
+ * A function that  references its own  type.
+ */
+export declare function f3(): typeof f3 | undefined;
+
+export { }

build-tests/api-extractor-scenarios/src/typeOf3/index.ts

@@ -0,0 +1,26 @@
+// Copyright (c) Microsoft Corporation. All rights reserved. Licensed under the MIT license.
+// See LICENSE in the project root for license information.
+
+/**
+ * A function that references its own parameter type.
+ * @public
+ */
+export function f1(x: number): typeof x {
+  return x;
+}
+
+/**
+ * A function that indirectly references its own  parameter type.
+ * @public
+ */
+export function f2(x: number): keyof typeof x {
+  return 'valueOf';
+}
+
+/**
+ * A function that  references its own  type.
+ * @public
+ */
+export function f3(): typeof f3 | undefined {
+  return undefined;
+}

common/changes/@microsoft/api-extractor/octgonz-ae-typeof-fix_2020-09-29-01-58.json

@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "packageName": "@microsoft/api-extractor",
+      "comment": "Fix an InternalError reported when a declaration referred to itself using \"tyepof\"",
+      "type": "patch"
+    }
+  ],
+  "packageName": "@microsoft/api-extractor",
+  "email": "[email protected]"
+}