Add UnionAttribute and IUnion interface to System.Runtime.CompilerServices#127001

Merged

eiriktsarpalis merged 11 commits intomainfrom

copilot/add-union-attribute-and-iuunion-interface

Apr 17, 2026

Commits on Apr 16, 2026

Initial plan
Copilot
authored
Add UnionAttribute and IUnion interface to System.Runtime.CompilerServices

Copilot
and
eiriktsarpalis
authored
Apply suggestion from @eiriktsarpalis
eiriktsarpalis
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Add comprehensive XML documentation for UnionAttribute and IUnion

Copilot
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eiriktsarpalis
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Document Value property per language spec; seal UnionAttribute in ref assembly

Copilot
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eiriktsarpalis
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Update src/libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/UnionAttribute.cs

eiriktsarpalis
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Copilot
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Remove proposal links and simplify XML docs to avoid naming specific patterns

Copilot
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eiriktsarpalis
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Manual cleanup of XML comments
eiriktsarpalis
committed
Remove IUnionTests and TestUnion test class per review feedback

Copilot
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eiriktsarpalis
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Fix IUnion XML docs: implementing interface is not required for union behaviors

Copilot
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AlekseyTs
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Change UnionAttribute Inherited to false — derived types aren't unions by default

Copilot
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AlekseyTs
authored