Collection expression arguments: CollectionBuilder items parameter should be last
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Feature - Dictionary Expressions
- Dominant language
- C#
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Description
For `CollectionBuilderAttribute` create methods, the `ReadOnlySpan` parameter for items should be last rather than first.
See [LDM-2025-03-12](https://github.com/dotnet/csharplang/blob/main/meetings/2025/LDM-2025-03-12.md#collection-builder-method-parameter-order).
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the linked LDM-2025-03-12 discussion and search the Roslyn compiler for CollectionBuilderAttribute create methods. Verify the collection expression handling and update it so the ReadOnlySpan items parameter is last, with tests covering the parameter order.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- csharp
- Domain
- compilers
- Issue type
- Feature
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100