Comments dropped for type abbreviations of tuples, lists and string: "entity was not registered before"

[nojaf]

Summary

fsdocs (23.0.0-alpha.1) fails to read the XML comments of type abbreviations whose target is a tuple, a list or string, logging Could not read comments from entity ... The entity System.Tuple2 was not registered before!`. The comments on those abbreviations are then dropped from the generated API docs.

Repro

Building the API docs for FSharp.Compiler.Service from https://github.com/dotnet/fsharp gives 20 of these. The abbreviation and the type that the resolver stumbles on:

FSharp.Compiler.AbstractIL.IL.ILAttributeNamedArg            <- System.Tuple`4
FSharp.Compiler.AbstractIL.IL.ILGenericArgs                  <- Microsoft.FSharp.Collections.FSharpList`1
FSharp.Compiler.AbstractIL.IL.ILParameters                   <- Microsoft.FSharp.Collections.FSharpList`1
FSharp.Compiler.AbstractIL.ILBinaryReader.ILReaderMetadataSnapshot <- System.Tuple`3
FSharp.Compiler.CodeAnalysis.FileName                        <- System.String
FSharp.Compiler.EditorServices.CompletionPath                <- System.Tuple`2
FSharp.Compiler.Syntax.LongIdent                             <- Microsoft.FSharp.Collections.FSharpList`1
FSharp.Compiler.Syntax.SynAttributes                         <- Microsoft.FSharp.Collections.FSharpList`1
FSharp.Compiler.Text.Position01                              <- System.Tuple`2
FSharp.Compiler.Text.Range01                                 <- System.Tuple`2

Minimal equivalents:

/// A position as a zero-based line and column
type Position01 = int * int

/// A long identifier
type LongIdent = Ident list

/// A file name
type FileName = string

Stack trace:

warning: Could not read comments from entity 'FSharp.Compiler.AbstractIL.IL.ILAttributeNamedArg': System.Exception: The entity System.Tuple`4 was not registered before!
   at Microsoft.FSharp.Core.PrintfModule.PrintFormatToStringThenFail@1447.Invoke(String message)
   at FSharp.Formatting.ApiDocs.CrossReferenceResolver.mfvToCref(FSharpMemberOrFunctionOrValue mfv) in src/FSharp.Formatting.ApiDocs/CrossReferenceResolver.fs:line 476
   at FSharp.Formatting.ApiDocs.CrossReferenceResolver.tryResolveCrossReferenceForMemberByXmlSig(String memberXmlSig) in src/FSharp.Formatting.ApiDocs/CrossReferenceResolver.fs:line 494
   at FSharp.Formatting.ApiDocs.CrossReferenceResolver.ResolveCref(String cref) in src/FSharp.Formatting.ApiDocs/CrossReferenceResolver.fs:line 633
   at FSharp.Formatting.ApiDocs.CrossReferenceResolver.IsLocal(String cref) in src/FSharp.Formatting.ApiDocs/CrossReferenceResolver.fs:line 662
   at FSharp.Formatting.ApiDocs.SymbolReader.readCommentAndCommands(ReadingContext ctx, String xmlSig, FSharpOption`1 m)
   at FSharp.Formatting.ApiDocs.SymbolReader.readCommentsInto[c](FSharpSymbol sym, ReadingContext ctx, String xmlDocSig, FSharpFunc`2 f)
   at FSharp.Formatting.ApiDocs.SymbolReader.tryReadMember(ReadingContext ctx, String entityUrl, ApiDocMemberKind kind, FSharpMemberOrFunctionOrValue memb)

It looks like mfvToCref expects every entity reachable from a member signature to have been registered up front, but the abbreviated types from FSharp.Core and the BCL (System.Tuple, FSharpList, System.String) never are. Expected: the abbreviation's own comment is read regardless of whether the target type can be cross-referenced, and unresolvable targets simply do not get a link.

Environment: fsdocs-tool 23.0.0-alpha.1, Linux, .NET SDK 11.0.100-rc.1.