[RGen] Add new helper method in the text writter to append DynamicDependency attrs (#23407)

This attribute will be added in the protocol generation.

---------

Co-authored-by: GitHub Actions Autoformatter <[email protected]>

Author: mandel-macaque

src/rgen/Microsoft.Macios.Generator/IO/TabbedStringBuilderExtensions.cs

@@ -130,4 +130,19 @@ public static TabbedWriter<StringWriter> AppendPreserveAttribute (this TabbedWri
 		self.WriteLine ($"[Preserve (Conditional = {conditional.ToString ().ToLower ()})]");
 		return self;
 	}
+
+	/// <summary>
+	/// Appends a `[DynamicDependency]` attribute to the current writer.
+	/// This attribute is used to indicate that a member has a dynamic dependency on another member.
+	/// </summary>
+	/// <param name="self">A tabbed string writer.</param>
+	/// <param name="member">The member that is dynamically depended upon.</param>
+	/// <returns>The current writer.</returns>
+	public static TabbedWriter<StringWriter> AppendDynamicDependencyAttribute (this TabbedWriter<StringWriter> self,
+		string member)
+	{
+
+		self.WriteLine ($"[DynamicDependency ({member})]");
+		return self;
+	}
 }

tests/rgen/Microsoft.Macios.Generator.Tests/IO/TabbedStringBuilderTests.cs

@@ -301,6 +301,22 @@ public void AppendPreserveAttribute (bool conditional, int tabCount, string expe
 		Assert.Equal (expected, result);
 	}
 
+	[Theory]
+	[InlineData ("\"MyMember\"", 0, "")]
+	[InlineData ("\"MyOtherMember\"", 1, "\t")]
+	[InlineData ("nameof(MyProperty)", 5, "\t\t\t\t\t")]
+	public void AppendDynamicDependencyAttributeTests (string member, int tabCount, string expectedTabs)
+	{
+		var expected = $"{expectedTabs}[DynamicDependency ({member})]\n";
+		string result;
+		using (var block = new TabbedStringBuilder (sb, tabCount)) {
+			block.AppendDynamicDependencyAttribute (member);
+			result = block.ToCode ();
+		}
+
+		Assert.Equal (expected, result);
+	}
+
 	[Theory]
 	[InlineData (0, "")]
 	[InlineData (1, "\t")]