Update option names and docs

docs/illink-tasks.md

@@ -53,20 +53,19 @@ The linker can be invoked as an MSBuild task, `ILLink`. We recommend not using t
         ExtraArgs="-t -c link" />
 ```
 
-## Default Linking Behaviour
+## Default Linking Behavior
 
-### .NET 5.0
+The default in the .NET Core SDK is to trim framework assemblies only, in a conservative assembly-level mode (`copyused` action). Third-party libraries and the app will be analyzed but not trimmed. Other SDKs may modify these defaults.
 
-By default, the linker will operate in a full linking mode for all framework or 
-core managed assemblies. The 3rd party libraries or final app will be analyzed but not linked.
-This setting can be altered by setting `_TrimmerDefaultAction` property to different
-linker action mode.
+## Customizing Linking Behavior
 
-### .NET 3.x
+`TrimMode` can be used to set the trimming behavior for framework assemblies. Additional assemblies can be given
+metadata `IsTrimmable` and they will also be trimmed using this mode, or they can have per-assembly `TrimMode` which
+takes precedence over the global `TrimMode`.
 
-By default, the linker will operate in a conservative mode that keeps
-all managed assemblies that aren't part of the framework (they are
-kept intact, and the linker simply copies them).
+## Reflection
+
+Note: this section is out-of-date. New versions of the linker can understand some of these reflection patterns.
 
 Applications or frameworks (including ASP<span />.NET Core and WPF) that use reflection or related dynamic features will often break when trimmed, because the linker does not know about this dynamic behavior, and can not determine in general which framework types will be required for reflection at runtime. To trim such apps, you will need to tell the linker about any types needed by reflection in your code, and in packages or frameworks that you depend on. Be sure to test your apps after trimming.
 

src/ILLink.Tasks/LinkTask.cs

@@ -14,7 +14,7 @@ public class ILLink : ToolTask
 		///   Paths to the assembly files that should be considered as
 		///   input to the linker.
 		///   Optional metadata:
-		///       Action ("copy", "link", etc...): sets the illink action to take for this assembly.
+		///       TrimMode ("copy", "link", etc...): sets the illink action to take for this assembly.
 		///   There is an optional metadata for each optimization that can be set to "True" or "False" to
 		///   enable or disable it per-assembly:
 		///       BeforeFieldInit
@@ -159,7 +159,7 @@ public class ILLink : ToolTask
 		///   Sets the default action for assemblies.
 		///   Maps to '-c' and '-u'.
 		/// </summary>
-		public string DefaultAction { get; set; }
+		public string TrimMode { get; set; }
 
 		/// <summary>
 		///   A list of custom steps to insert into the linker pipeline.
@@ -261,10 +261,10 @@ protected override string GenerateResponseFileCommands ()
 
 				args.Append ("-reference ").AppendLine (Quote (assemblyPath));
 
-				string action = assembly.GetMetadata ("Action");
-				if (!String.IsNullOrEmpty (action)) {
+				string trimMode = assembly.GetMetadata ("TrimMode");
+				if (!String.IsNullOrEmpty (trimMode)) {
 					args.Append ("-p ");
-					args.Append (action);
+					args.Append (trimMode);
 					args.Append (" ").AppendLine (Quote (assemblyName));
 				}
 
@@ -349,8 +349,8 @@ protected override string GenerateResponseFileCommands ()
 			if (LinkSymbols)
 				args.AppendLine ("-b");
 
-			if (DefaultAction != null)
-				args.Append ("-c ").Append (DefaultAction).Append (" -u ").AppendLine (DefaultAction);
+			if (TrimMode != null)
+				args.Append ("-c ").Append (TrimMode).Append (" -u ").AppendLine (TrimMode);
 
 			if (CustomSteps != null) {
 				foreach (var customStep in CustomSteps) {

test/ILLink.Tasks.Tests/ILLink.Tasks.Tests.cs

@@ -21,12 +21,12 @@ public class TaskArgumentTests
 		public static IEnumerable<object[]> AssemblyPathsCases => new List<object[]> {
 			new object [] {
 				new ITaskItem [] {
-					new TaskItem ("Assembly.dll", new Dictionary<string, string> { { "action", "copy" } })
+					new TaskItem ("Assembly.dll", new Dictionary<string, string> { { "trimmode", "copy" } })
 				}
 			},
 			new object [] {
 				new ITaskItem [] {
-					new TaskItem ("Assembly.dll", new Dictionary<string, string> { { "Action", "Copy" } })
+					new TaskItem ("Assembly.dll", new Dictionary<string, string> { { "TrimMode", "Copy" } })
 				}
 			},
 			new object [] {
@@ -75,10 +75,10 @@ public void TestAssemblyPaths (ITaskItem[] assemblyPaths)
 
 				foreach (var item in assemblyPaths) {
 					var assemblyPath = item.ItemSpec;
-					var action = item.GetMetadata ("action");
-					if (String.IsNullOrEmpty (action))
+					var trimMode = item.GetMetadata ("TrimMode");
+					if (String.IsNullOrEmpty (trimMode))
 						continue;
-					AssemblyAction expectedAction = (AssemblyAction) Enum.Parse (typeof (AssemblyAction), action, ignoreCase: true);
+					AssemblyAction expectedAction = (AssemblyAction) Enum.Parse (typeof (AssemblyAction), trimMode, ignoreCase: true);
 					AssemblyAction actualAction = (AssemblyAction) context.Actions[Path.GetFileNameWithoutExtension (assemblyPath)];
 					Assert.Equal (expectedAction, actualAction);
 				}
@@ -89,7 +89,7 @@ public void TestAssemblyPaths (ITaskItem[] assemblyPaths)
 		public void TestAssemblyPathsWithInvalidAction ()
 		{
 			var task = new MockTask () {
-				AssemblyPaths = new ITaskItem[] { new TaskItem ("Assembly.dll", new Dictionary<string, string> { { "action", "invalid" } }) }
+				AssemblyPaths = new ITaskItem[] { new TaskItem ("Assembly.dll", new Dictionary<string, string> { { "TrimMode", "invalid" } }) }
 			};
 			Assert.Throws<ArgumentException> (() => task.CreateDriver ());
 		}
@@ -379,12 +379,12 @@ public void TestInvalidFeatureSettings ()
 		public void TestExtraArgs ()
 		{
 			var task = new MockTask () {
-				DefaultAction = "copy",
+				TrimMode = "copy",
 				ExtraArgs = "-c link"
 			};
 			using (var driver = task.CreateDriver ()) {
 				Assert.Equal (AssemblyAction.Copy, driver.Context.UserAction);
-				// Check that ExtraArgs can override DefaultAction
+				// Check that ExtraArgs can override TrimMode
 				Assert.Equal (AssemblyAction.Link, driver.Context.CoreAction);
 			}
 		}
@@ -419,13 +419,13 @@ public void TestLinkSymbols (bool linkSymbols)
 		[InlineData ("copy")]
 		[InlineData ("link")]
 		[InlineData ("copyused")]
-		public void TestDefaultAction (string defaultAction)
+		public void TestGlobalTrimMode (string trimMode)
 		{
 			var task = new MockTask () {
-				DefaultAction = defaultAction
+				TrimMode = trimMode
 			};
 			using (var driver = task.CreateDriver ()) {
-				var expectedAction = (AssemblyAction) Enum.Parse (typeof (AssemblyAction), defaultAction, ignoreCase: true);
+				var expectedAction = (AssemblyAction) Enum.Parse (typeof (AssemblyAction), trimMode, ignoreCase: true);
 				Assert.Equal (expectedAction, driver.Context.CoreAction);
 				Assert.Equal (expectedAction, driver.Context.UserAction);
 			}
@@ -435,7 +435,7 @@ public void TestDefaultAction (string defaultAction)
 		public void TestInvalidDefaultAction ()
 		{
 			var task = new MockTask () {
-				DefaultAction = "invalid"
+				TrimMode = "invalid"
 			};
 			Assert.Throws<ArgumentException> (() => task.CreateDriver ());
 		}