Fix idempotency issue with comment after type decl without equals, 3145

[dawedawe]

Fixes #3145

It's actually about type decls without an equals but a comment after.
See here

Ideally we could detect that in expressionExceedsPageWidth (or even below that) as the info.ConfirmedMultiline is the root cause, but I don't see a good way to pass that down there.

[Copilot]

Pull Request Overview

This PR fixes an idempotency issue where a type declaration without an = but with a trailing comment would always emit an extra newline.

• Introduces a new formatter function that omits the newline in this specific case
• Updates genTypeDefn to pick newline vs. no-newline behavior based on presence of EqualsToken
• Adds a targeted test and updates the changelog entry

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/Fantomas.Core/Context.fsi	Added signature for sepSpaceOrIndentIfExpressionExceedsPageWidth
src/Fantomas.Core/Context.fs	Implemented new separator and wired it into expression logic
src/Fantomas.Core/CodePrinter.fs	Updated genTypeDefn to select between the two separator functions
src/Fantomas.Core.Tests/TypeDeclarationTests.fs	Added test for type decl without = and trailing comment
CHANGELOG.md	Documented the fix under Fixed

Comments suppressed due to low confidence (2)

src/Fantomas.Core.Tests/TypeDeclarationTests.fs:3686

• Add a complementary test for a type alias with an = and trailing comment to ensure the original newline logic (sepSpaceOrIndentAndNlnIfExpressionExceedsPageWidth) remains correct.

let ``type without body but with comment produces superfluous newline, 3145`` () =

src/Fantomas.Core/Context.fs:751

• [nitpick] Consider renaming this function to something like sepSpaceOrIndentWithoutNlnIfExpressionExceedsPageWidth to more clearly indicate that it omits the newline behavior.

let sepSpaceOrIndentIfExpressionExceedsPageWidth expr (ctx: Context) =

[nojaf]

Great, thank you!

[nojaf]

@dawedawe do we want to release a 7.0.2?

[dawedawe]

@dawedawe do we want to release a 7.0.2?

I'll look into one or two more fixes in the next couple of days. Let's release after that.