#10227·csharplang

[Proposal]: partial extension members

Author: jcouvCreated Jun 15, 2026Updated Jul 2, 2026
LabelsProposal champion

Specification: https://github.com/dotnet/csharplang/blob/main/proposals/partial-extension-members.md Discussion: https://github.com/dotnet/csharplang/discussions/10228

Summary

Allow partial extension members in extension block in partial enclosing static classes:

cs
public static partial class E
{
    extension(int i)
    {
        public partial void M();
    }
}
public static partial class E
{
    extension(int i)
    {
        public partial void M() { }
    }
}

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