Port "Fix flow node improper reuse"

[Andarist]

ports microsoft/TypeScript#60662

[Copilot]

Pull Request Overview

Ports the fix for improper reuse of flow nodes by clearing the FlowNode on FlowNodeData when a node is unreachable.

• Clears the FlowNode field for unreachable nodes to avoid reuse
• Keeps existing JSDoc parent binding and child traversal sequence intact

Comments suppressed due to low confidence (2)

internal/binder/binder.go:1568

• [nitpick] The variable name hasFlowNodeData suggests a boolean, but it holds a FlowNodeData pointer; consider renaming it to flowNodeData for clarity.

hasFlowNodeData := node.FlowNodeData()

internal/binder/binder.go:1568

• Consider adding a unit test for the case where checkUnreachable(node) returns true, verifying that FlowNode is cleared to prevent improper reuse.

if b.checkUnreachable(node) {

[ahejlsberg]

We're not doing incremental parsing in Corsa. When a source file is modified, we always completely rebuild the AST. So, I don't think there's a scenario where the code in this PR is needed.

[Andarist]

That's cool 👍 I was wondering if the AST reuse is still done here

[jakebailey]

Marked this as not needed on the PR board.