Editor: Fix Record fields completion in update record with partial field name

[edgarfgp]

Description

Fix Record fields completion in update record with partial field name

Checklist

• Test cases added
• Release notes entry updated

[github-actions]

❗ Release notes required

---

✅ Found changes and release notes in following paths:

Change path	Release notes path	Description
src/Compiler	docs/release-notes/.FSharp.Compiler.Service/10.0.100.md

[T-Gro]

/backport to release/dev18.0

[github-actions]

Started backporting to release/dev18.0: https://github.com/dotnet/fsharp/actions/runs/18136678632

[kerams]

I don't quite understand this. Both work for me in the latest VS 2026, and isn't rangeContainsPos field.Range pos true whenever posEq pos field.Range.End is (given let rangeContainsPos (m1: range) p = posGeq p m1.Start && posGeq m1.End p), making the old and updated condition have the same truth table?

[auduchinok]

I agree with @kerams here.

@edgarfgp Could you please explain what exactly does this change do?

rangeContainsPos field.Range pos includes the case when posEq pos field.Range.End is true.
How is it possible that the second part of the condition is ever true then?

And what does the checking the specific case of no expression add here? Especially in the branch that should never be true.