Docgen: Fix function param for const function expression

packages/docgen/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+### Bug Fixes
+
+- Fix getting param annotations for exported variables assigned to function expressions ([#tbd](https://github.com/WordPress/gutenberg/pull/tbd)).
+
 ## 2.2.0 (2024-06-26)
 
 ## 2.1.0 (2024-06-15)
@@ -98,7 +102,7 @@
 
 ### Bug Fixes
 
-- Fix getting param annotations for default exported functions. ([#31603](https://github.com/WordPress/gutenberg/pull/31603))
+- Fix getting param annotations for default exported functions ([#31603](https://github.com/WordPress/gutenberg/pull/31603)).
 
 ## 1.17.0 (2021-04-29)
 

packages/docgen/lib/get-type-annotation.js

@@ -405,6 +405,10 @@ function unwrapWrappedSelectors( token ) {
  return token;
  }
 
+ if ( babelTypes.isFunctionExpression( token ) ) {
+ return token;
+ }
+
  if ( babelTypes.isArrowFunctionExpression( token ) ) {
  return token;
  }
@@ -433,7 +437,7 @@ function unwrapWrappedSelectors( token ) {
 
 /**
  * @param {ASTNode} token
- * @return {babelTypes.ArrowFunctionExpression | babelTypes.FunctionDeclaration} The function token.
+ * @return {babelTypes.ArrowFunctionExpression | babelTypes.FunctionDeclaration | babelTypes.FunctionExpression} The function token.
  */
 function getFunctionToken( token ) {
  let resolvedToken = token;
@@ -517,8 +521,7 @@ function getQualifiedObjectPatternTypeAnnotation( tag, paramType ) {
 function getParamTypeAnnotation( tag, declarationToken, paramIndex ) {
  const functionToken = getFunctionToken( declarationToken );
 
- // Otherwise find the corresponding parameter token for the documented parameter.
- let paramToken = functionToken.params[ paramIndex ];
+ let paramToken = functionToken?.params[ paramIndex ];
 
  // This shouldn't happen due to our ESLint enforcing correctly documented parameter names but just in case
  // we'll give a descriptive error so that it's easy to diagnose the issue.

packages/docgen/test/get-type-annotation.js

@@ -31,12 +31,12 @@ describe( 'Type annotations', () => {
  expect( result ).toBeFalsy();
  } );
 
- const paramTag = {
+ const paramTag = /** @type {const} */ ( {
  tag: 'param',
  type: '',
  name: 'foo',
  description: 'A foo parameter',
- };
+ } );
 
  describe( 'simple types', () => {
  const keywordTypes = [
@@ -463,4 +463,22 @@ describe( 'Type annotations', () => {
  expect( getStateArgType( code ) ).toBe( 'number' );
  } );
  } );
+
+ it( 'should find types in a constant function expression assignment', () => {
+ const node = parse( `
+ export const __unstableAwaitPromise = function < T >( promise: Promise< T > ): {
+ type: 'AWAIT_PROMISE';
+ promise: Promise< T >;
+ } {
+ return {
+ type: 'AWAIT_PROMISE',
+ promise,
+ };
+ };
+ ` );
+
+ expect(
+ getTypeAnnotation( { tag: 'param', name: 'promise' }, node, 0 )
+ ).toBe( 'Promise< T >' );
+ } );
 } );