[Jake Bailey (jakebailey)]

The old way is technically violating the type annotations, though they are not currently checked.

[Copilot]

🟡 Changes recommended

The shortened formatting range excludes emitted trailing comments, causing semicolons to remain despite SemicolonPreferenceRemove; the full printed-text range must be preserved and covered by a regression test.

1 open issue

• Preserve full formatting range when handling trailing comments · New

What changed in this PR

This PR keeps printed formatting fragments separate from source-file statement lists, preserving valid AST structure in the compiler and language server.

Changes:

• Create synthetic source files as text and line-map contexts, with empty statement lists.
• Update formatting callers and assign parent pointers to all positioned children.
• Add formatting tests for non-statement fragments.

File	Description
tsc/​internal/​printer/​syntheticfile.go	Remove fragments from synthetic source-file statements.
tsc/​internal/​printer/​changetrackerwriter.go	Set parent pointers for every child.
tsc/​internal/​ls/​completions.go	Update snippet formatting to use the revised helper.
tsc/​internal/​ls/​change/​trackerimpl.go	Format positioned fragments separately from source-file context.
tsc/​internal/​format/​api_test.go	Test fragment formatting and valid source-file children.
tsc/​internal/​api/​session.go	Update insertion formatting to use the revised helper.

_{Review effort: Balanced}

[Copilot]

🔵 Needs a closer look

With an empty statement list, indentation lookups repeatedly scan from the fragment’s start, potentially causing quadratic formatting time for large functions or classes with many multiline branches.

No open issues 🎉

1 previously missed issue

In code that hasn't changed since last review

Restrict preceding-token scans to the enclosing if node

tsc/​internal/​printer/​syntheticfile.go:43

With an empty statement list, the FindPrecedingToken call in format/indent.go:502 scans from the start of the fragment for each multiline if/else whose indentation needs this lookup. Repeated branches in a large function or class can therefore cause quadratic token scanning during formatting. Keep the text-only source file, but change that lookup to astnav.FindPrecedingTokenEx(sourceFile, child.Pos(), parent, false) so it searches within the enclosing if node.

1 resolved since last review

• Preserve full formatting range when handling trailing comments

_{Review effort: Balanced}

[Copilot]

🟢 Approval recommended

The review reports no active issues with the changes separating formatting fragments from source-file statement lists.

No open issues 🎉

_{Review effort: Balanced}