Extensions: ExtensionGroupingName and ExtensionMarkerName API proposal #80163
Description
Background and Motivation
The metadata design for extensions relies on nested types with content-based names. There's a grouping type name and a marker type name.
This proposal makes those names available via public APIs. Two usages have already been identified for those public APIs within rolsyn.
Relates to test plan #76130
Proposed API
namespace Microsoft.CodeAnalysis
{
public interface ITypeSymbol : INamespaceOrTypeSymbol
{
[...]
/// <summary>
/// Is this a symbol for an extension declaration.
/// </summary>
+ [MemberNotNullWhen(true, nameof(ExtensionGroupingName), nameof(ExtensionMarkerName))]
bool IsExtension { get; }
+ /// <summary>
+ /// For extensions, returns the synthesized identifier for the grouping type.
+ /// Returns null otherwise.
+ /// </summary>
+ string? ExtensionGroupingName { get; }
+ /// <summary>
+ /// For extensions, returns the synthesized identifier for the marker type.
+ /// Returns null otherwise.
+ /// </summary>
+ string? ExtensionMarkerName { get; }
}
}Here are some eamples of returned values (it's a prefix followed by a hash):
Assert.Equal("<G>$B8D310208B4544F25EEBACB9990FC73B", extension.ExtensionGroupingName);
Assert.Equal("<M>$4F043C3369CC5922051EC35190062B5C", extension.ExtensionMarkerName);
Alternative Designs
The ExtensionMarkerName is already available via MetadataName API, but was added for consistency with ExtensionsGroupingName
Risks
N/A