Convert BAML to XAML when exporting a project from the command line

A WPF assembly keeps its windows and pages as BAML, so a project exported
without converting them back is missing the parts that make it a WPF
application - and the reader has no XAML to look at either. The CLI could
do the conversion since --decompile-baml was added, but only if asked,
which meant that everything the project exporter learned about WPF (Page
and ApplicationDefinition items, resources, generated members removed
from the code-behind) was invisible to anyone following issue #2253 from
the command line.

The flag is kept and ignored: it is documented and scripted against, and
asking for what is now the default has to keep working.

The test fixture is a real .g.resources container rather than a directly
embedded .baml stream, because only entries inside a container reach
WriteResourceToFile - a standalone .baml is copied out untouched, which
is worth its own look.

Assisted-by: Claude:claude-opus-5:Claude Code

ICSharpCode.ILSpyCmd.Tests/ICSharpCode.ILSpyCmd.Tests.csproj

@@ -24,4 +24,10 @@
     <ProjectReference Include="..\ICSharpCode.ILSpyCmd\ICSharpCode.ILSpyCmd.csproj" />
   </ItemGroup>
 
+  <ItemGroup>
+    <!-- A BAML stream inside a .g.resources container, the way the WPF build puts one into an
+         assembly, so that exporting this assembly as a project has one to convert. -->
+    <EmbeddedResource Include="fixtures\test.g.resources" LogicalName="ICSharpCode.ILSpyCmd.Tests.g.resources" />
+  </ItemGroup>
+
 </Project>

ICSharpCode.ILSpyCmd.Tests/ProjectExportBamlTests.cs

@@ -0,0 +1,94 @@
+// Copyright (c) 2026 Siegfried Pammer
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy of this
+// software and associated documentation files (the "Software"), to deal in the Software
+// without restriction, including without limitation the rights to use, copy, modify, merge,
+// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons
+// to whom the Software is furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in all copies or
+// substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
+// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
+// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
+// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
+// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+// DEALINGS IN THE SOFTWARE.
+
+using System.IO;
+using System.Linq;
+using System.Threading.Tasks;
+
+using NUnit.Framework;
+
+using static ICSharpCode.ILSpyCmd.Tests.CliTestRunner;
+
+namespace ICSharpCode.ILSpyCmd.Tests
+{
+	/// <summary>
+	/// This assembly carries "mainwindow.baml" as an embedded resource, so exporting it as a
+	/// project exercises what happens to a BAML stream on the way into the project.
+	/// </summary>
+	[TestFixture]
+	public class ProjectExportBamlTests
+	{
+		static readonly string testAssemblyPath = typeof(ProjectExportBamlTests).Assembly.Location;
+
+		string outputDirectory;
+
+		[SetUp]
+		public void SetUp()
+		{
+			outputDirectory = Path.Combine(Path.GetTempPath(), Path.GetRandomFileName());
+			Directory.CreateDirectory(outputDirectory);
+		}
+
+		[TearDown]
+		public void TearDown()
+		{
+			if (Directory.Exists(outputDirectory))
+				Directory.Delete(outputDirectory, recursive: true);
+		}
+
+		string ProjectFileContent()
+		{
+			string projectFile = Directory.EnumerateFiles(outputDirectory, "*.csproj").Single();
+			return File.ReadAllText(projectFile);
+		}
+
+		[Test]
+		public async Task BamlBecomesXamlWithoutAskingForIt()
+		{
+			var result = await RunAsync(testAssemblyPath, "--disable-updatecheck", "-p", "-o", outputDirectory);
+
+			Assert.That(result.ExitCode, Is.EqualTo(0), result.Error);
+			string xamlFile = Path.Combine(outputDirectory, "mainwindow.xaml");
+			Assert.That(File.Exists(xamlFile), Is.True, "the BAML resource is exported as XAML");
+			Assert.That(File.ReadAllText(xamlFile), Does.Contain("Hello from BAML"));
+		}
+
+		[Test]
+		public async Task TheProjectNamesTheXamlAsAPage()
+		{
+			await RunAsync(testAssemblyPath, "--disable-updatecheck", "-p", "-o", outputDirectory);
+
+			string project = ProjectFileContent();
+			Assert.Multiple(() => {
+				Assert.That(project, Does.Contain("<Page Include=\"mainwindow.xaml\""));
+				Assert.That(project, Does.Not.Contain("mainwindow.baml"), "the raw stream is not carried along as well");
+			});
+		}
+
+		[Test]
+		public async Task TheOldOptInFlagStillWorks()
+		{
+			// It is documented and scripted against; asking for what is now the default has to
+			// keep meaning the same thing.
+			var result = await RunAsync(testAssemblyPath, "--disable-updatecheck", "-p", "-o", outputDirectory, "--decompile-baml");
+
+			Assert.That(result.ExitCode, Is.EqualTo(0), result.Error);
+			Assert.That(File.Exists(Path.Combine(outputDirectory, "mainwindow.xaml")), Is.True);
+		}
+	}
+}

ICSharpCode.ILSpyCmd/IlspyCmdProgram.cs

@@ -82,8 +82,8 @@ Examples:
     Extract a single resource. If the name ends with .baml, the output is decompiled XAML; otherwise raw bytes.
         ilspycmd sample.dll --resource sample.g.resources/mainwindow.baml -o c:\decompiled
 
-    Decompile assembly as a compilable project and convert all BAML resources to XAML Page items.
-        ilspycmd sample.dll -p -o c:\decompiled --decompile-baml
+    Decompile assembly as a compilable project. BAML resources become XAML Page items.
+        ilspycmd sample.dll -p -o c:\decompiled
 ")]
 	[HelpOption("-h|--help")]
 	[ProjectOptionRequiresOutputDirectoryValidation]
@@ -145,7 +145,7 @@ Examples:
 		[Option("--resource <name>", "Extract a single resource by name (as printed by --list-resources). Resources whose name ends with '.baml' are decompiled to XAML.", CommandOptionType.SingleValue)]
 		public string ResourceName { get; }
 
-		[Option("--decompile-baml", "When used with -p, decompile BAML resources to XAML files (Page items) instead of leaving them as raw byte streams.", CommandOptionType.NoValue)]
+		[Option("--decompile-baml", "Deprecated: -p decompiles BAML resources to XAML files (Page items) on its own. Accepted so that existing scripts keep working.", CommandOptionType.NoValue)]
 		public bool DecompileBamlFlag { get; }
 
 		[Option("--dump-table <table>", "Dump a metadata table: prints RID, token, names, heap offsets and coded indexes of every row. <table> is the ECMA-335 table name (e.g. TypeDef, Property, MethodSemantics; case-insensitive) or table number (decimal or 0x-prefixed hex, e.g. 0x17).", CommandOptionType.SingleValue)]
@@ -795,19 +795,14 @@ Examples:
 			}
 			var settings = GetSettings(module);
 			var debugInfo = TryLoadPDB(module);
-			WholeProjectDecompiler decompiler;
-			if (DecompileBamlFlag)
-			{
-				var bamlTypeSystem = new BamlDecompilerTypeSystem(module, resolver);
-				var bamlSettings = new BamlDecompilerSettings {
-					ThrowOnAssemblyResolveErrors = settings.ThrowOnAssemblyResolveErrors
-				};
-				decompiler = new BamlAwareWholeProjectDecompiler(settings, resolver, resolver, debugInfo, bamlTypeSystem, bamlSettings);
-			}
-			else
-			{
-				decompiler = new WholeProjectDecompiler(settings, resolver, null, resolver, debugInfo);
-			}
+			// A WPF assembly keeps its XAML as BAML, so a project exported without converting it
+			// back is missing every window and page it is made of.
+			var bamlTypeSystem = new BamlDecompilerTypeSystem(module, resolver);
+			var bamlSettings = new BamlDecompilerSettings {
+				ThrowOnAssemblyResolveErrors = settings.ThrowOnAssemblyResolveErrors
+			};
+			WholeProjectDecompiler decompiler = new BamlAwareWholeProjectDecompiler(settings, resolver, resolver,
+				debugInfo, bamlTypeSystem, bamlSettings);
 			ProjectId projectId;
 			using (var projectFileWriter = new StreamWriter(File.Create(projectFileName)))
 				projectId = decompiler.DecompileProject(module, Path.GetDirectoryName(projectFileName), projectFileWriter);

ICSharpCode.ILSpyCmd/README.md

@@ -39,8 +39,8 @@ Options:
                                           containers are listed individually as '<container>/<entry>'.
   --resource <name>                       Extract a single resource by name (as printed by --list-resources). Resources
                                           whose name ends with '.baml' are decompiled to XAML.
-  --decompile-baml                        When used with -p, decompile BAML resources to XAML files (Page items) instead
-                                          of leaving them as raw byte streams.
+  --decompile-baml                        Deprecated: -p decompiles BAML resources to XAML files (Page items) on its
+                                          own. Accepted so that existing scripts keep working.
   --dump-table <table>                    Dump a metadata table: prints RID, token, names, heap offsets and coded
                                           indexes of every row. <table> is the ECMA-335 table name (e.g. TypeDef,
                                           Property, MethodSemantics; case-insensitive) or table number (decimal or
@@ -121,8 +121,8 @@ Examples:
     Extract a single resource. If the name ends with .baml, the output is decompiled XAML; otherwise raw bytes.
         ilspycmd sample.dll --resource sample.g.resources/mainwindow.baml -o c:\decompiled
 
-    Decompile assembly as a compilable project and convert all BAML resources to XAML Page items.
-        ilspycmd sample.dll -p -o c:\decompiled --decompile-baml
+    Decompile assembly as a compilable project. BAML resources become XAML Page items.
+        ilspycmd sample.dll -p -o c:\decompiled
 ```
 
 ## Generate HTML diagrammers