dartdoc crashes when referring to the type parameter of a generic extension type with a typedef representation type

[srujzs]

The following code:

typedef TD<T> = T;

/// [T]
extension type ET<T>(TD<T> _) {}

crashes dartdoc with the following error:

Stack trace

dartdoc 8.0.9 (/Users/srujzs/Downloads/testdartdoc/dartdev) failed: type 'TypeParameterTypeImpl' is not a subtype of type 'ParameterizedType' in type cast
#0      new DefinedElementType._from (package:dartdoc/src/element_type.dart:281:16)
#1      new ElementType.for_ (package:dartdoc/src/element_type.dart:45:31)
#2      Nameable.getTypeFor (package:dartdoc/src/model/nameable.dart:85:19)
#3      ExtensionType.representationType (package:dartdoc/src/model/extension_type.dart:16:7)
#4      ExtensionType.representationType (package:dartdoc/src/model/extension_type.dart)
#5      ExtensionType.referenceChildren (package:dartdoc/src/model/extension_type.dart:79:10)
#6      CommentReferable.referenceBy (package:dartdoc/src/model/comment_referable.dart:64:38)
#7      _getMatchingLinkElement (package:dartdoc/src/markdown_processor.dart:176:15)
#8      getMatchingLinkElement (package:dartdoc/src/markdown_processor.dart:187:16)
#9      MarkdownDocument._makeLinkNode (package:dartdoc/src/markdown_processor.dart:313:18)
#10     new MarkdownDocument.withElementLinkResolver.<anonymous closure> (package:dartdoc/src/markdown_processor.dart:267:51)
#11     LinkSyntax._resolveReferenceLink (package:markdown/src/inline_syntaxes/link_syntax.dart:137:36)
#12     LinkSyntax._tryCreateReferenceLink (package:markdown/src/inline_syntaxes/link_syntax.dart:177:18)
#13     LinkSyntax.close (package:markdown/src/inline_syntaxes/link_syntax.dart:52:14)
#14     InlineParser._linkOrImage (package:markdown/src/inline_parser.dart:150:32)
#15     InlineParser.parse (package:markdown/src/inline_parser.dart:106:9)
#16     MarkdownDocument._parseInlineContent (package:dartdoc/src/markdown_processor.dart:298:67)
#17     MarkdownDocument._parseInlineContent (package:dartdoc/src/markdown_processor.dart:303:9)
#18     MarkdownDocument.parseMarkdownText (package:dartdoc/src/markdown_processor.dart:288:5)
#19     Documentation._parseDocumentation (package:dartdoc/src/model/documentation.dart:78:21)
#20     Documentation._renderDocumentation (package:dartdoc/src/model/documentation.dart:59:23)
#21     Documentation.asHtml (package:dartdoc/src/model/documentation.dart:44:5)
#22     DocumentationComment.documentationAsHtml (package:dartdoc/src/model/documentation_comment.dart:62:49)
#23     DocumentationComment.documentationAsHtml (package:dartdoc/src/model/documentation_comment.dart)
#24     EmptyGenerator.generate (package:dartdoc/src/generator/empty_generator.dart:27:25)
#25     Dartdoc.generateDocsBase (package:dartdoc/src/dartdoc.dart:203:21)
<asynchronous suspension>
#26     Dartdoc.generateDocs (package:dartdoc/src/dartdoc.dart:241:24)
<asynchronous suspension>
#27     Dartdoc.executeGuarded.<anonymous closure> (package:dartdoc/src/dartdoc.dart:273:9)
<asynchronous suspension>

Removing the typedef and just making the representation type T doesn't reproduce the error. Removing the doc comment doesn't reproduce the error.

Dart SDK version: 3.5.0-edge.667fa314c8e754125ba9a601a30a4587c68f6c3d (main) (Tue Jun 11 14:19:26 2024 -0700) on "macos_arm64"

This was discovered when running the try bots in https://dart-review.googlesource.com/c/sdk/+/370663. pkg-linux-release-try fails when trying to validate the SDK API docs.

[srujzs]

This also crashes if the doc on ET contains a [] referencing anything e.g. /// [Object] is sufficient to reproduce.

edit: If there's a declaration that uses ET e.g. an extension, this reproduces if [] is used on the extension anywhere or its members. If other declarations reference a member from this extension, that also reproduces this error.

/// [Object]
extension on ET {}

extension E on ET {
  int get i => 0;
}

/// [E.i]
int x = 0;

[srawlins]

Thanks for the clean repro! 🙏