Consider migrating Directory polyfills to extension(Directory) syntax

[thomhurst]

Summary

The Directory polyfill methods in Polyfill_Directory.cs currently use the Polyfill.EnumerateFiles(...) / Polyfill.GetFiles(...) etc. calling convention. With C# 14's extension(Type) syntax, these could be migrated to extension(Directory) so consumers can call Directory.EnumerateFiles(path, pattern, enumerationOptions) directly — matching the native .NET API surface.

Why this needs a major version bump

This would be a breaking change. Any consumer currently calling:

Polyfill.EnumerateFiles(path, pattern, options);
Polyfill.EnumerateDirectories(path, pattern, options);
Polyfill.EnumerateFileSystemEntries(path, pattern, options);
Polyfill.GetFiles(path, pattern, options);
Polyfill.GetDirectories(path, pattern, options);
Polyfill.GetFileSystemEntries(path, pattern, options);

would get a compilation error (CS0103) after upgrading, and would need to change to:

Directory.EnumerateFiles(path, pattern, options);
Directory.EnumerateDirectories(path, pattern, options);
// etc.

Why both patterns can't coexist

C# 14 extension(Directory) block members are still members of the enclosing Polyfill class at the IL level. Having both Polyfill.EnumerateFiles(...) and extension(Directory) { EnumerateFiles(...) } in the same static partial class Polyfill produces CS0111 (duplicate member signatures). So it's one or the other.

Affected methods

• EnumerateFiles(string, string, EnumerationOptions)
• EnumerateDirectories(string, string, EnumerationOptions)
• EnumerateFileSystemEntries(string, string, EnumerationOptions)
• GetFiles(string, string, EnumerationOptions)
• GetDirectories(string, string, EnumerationOptions)
• GetFileSystemEntries(string, string, EnumerationOptions)

Related

PR #515 added several new extension(Type) polyfills but intentionally kept the Directory methods unchanged for backwards compatibility.