Handle recursive aliases in named tuple rest elements

[Copilot]

This addresses microsoft/TypeScript#63584.

Recursive aliases using named tuple rest elements like ...tagged: T[] were being treated differently from structurally equivalent unnamed rest elements, producing a spurious TS2456 circularity error.

• Root cause

  • Alias deferral for tuple elements handled RestType specially, but missed the ArrayType nested under NamedTupleMember.
  • As a result, ...name: T[] could force eager alias resolution where ...T[] would defer.

• Checker change

  • Teach mayResolveTypeAlias to recurse through ArrayType nodes.
  • This makes named tuple rest members participate in the same deferral path as ordinary rest tuple elements.

• Regression coverage

  • Add a compiler test covering both recursive forms:
    • named rest in the first recursive tuple branch
    • named rest in a later tuple position

export type NamedRestDocNode1 =
    | string
    | ["i", ...tagged: NamedRestDocNode1[]]
    | ["li", index: number, ...NamedRestDocNode1[]];

export type NamedRestDocNode2 =
    | string
    | ["i", ...NamedRestDocNode2[]]
    | ["li", index: number, ...tagged: NamedRestDocNode2[]];

[Copilot]

Pull request overview

This PR fixes a checker circularity regression where recursive type aliases using named tuple rest elements (e.g. ...tagged: T[]) could trigger a spurious TS2456 circular reference error, despite being structurally equivalent to unnamed rest elements.

Changes:

• Extend Checker.mayResolveTypeAlias to recurse into ArrayType element types, matching the existing deferral behavior already applied to RestType wrapping an array.
• Add a compiler regression test covering recursive aliases with both unnamed and named tuple rest members (named rest in the first branch and in a later tuple position).
• Add new reference baselines (.types, .symbols, .js) for the new test.

Show a summary per file

File	Description
internal/checker/checker.go	Makes alias-resolution deferral logic see through ArrayType nodes so named tuple rest members don’t force eager alias resolution.
testdata/tests/cases/compiler/issue63584NamedTupleRestCircularReference.ts	New regression test for recursive aliases with named vs unnamed tuple rest elements.
testdata/baselines/reference/compiler/issue63584NamedTupleRestCircularReference.types	Expected type baseline for the new regression test.
testdata/baselines/reference/compiler/issue63584NamedTupleRestCircularReference.symbols	Expected symbol baseline for the new regression test.
testdata/baselines/reference/compiler/issue63584NamedTupleRestCircularReference.js	Expected JS baseline for the new regression test.

Copilot's findings

• Files reviewed: 5/5 changed files
• Comments generated: 0