Resolve generic descriptor method signatures in ILC

src/coreclr/tools/Common/Compiler/ProcessLinkerXmlBase.cs

@@ -530,7 +530,8 @@ protected static string GetAttribute(XPathNavigator nav, string attribute)
         public static string GetMethodSignature(MethodDesc meth, bool includeGenericParameters)
         {
             StringBuilder sb = new StringBuilder();
-            CecilTypeNameFormatter.Instance.AppendName(sb, meth.Signature.ReturnType);
+            var formatter = new CecilTypeNameFormatter(meth);
+            formatter.AppendName(sb, meth.Signature.ReturnType);
             sb.Append(' ');
             sb.Append(meth.GetName());
             if (includeGenericParameters && meth.HasInstantiation)
@@ -545,7 +546,7 @@ public static string GetMethodSignature(MethodDesc meth, bool includeGenericPara
                 if (i > 0)
                     sb.Append(',');
 
-                CecilTypeNameFormatter.Instance.AppendName(sb, meth.Signature[i]);
+                formatter.AppendName(sb, meth.Signature[i]);
             }
 
             sb.Append(')');
@@ -572,7 +573,14 @@ protected void LogWarning(XPathNavigator position, DiagnosticId id, params strin
 
         private sealed class CecilTypeNameFormatter : TypeNameFormatter
         {
-            public static readonly CecilTypeNameFormatter Instance = new CecilTypeNameFormatter();
+            public static readonly CecilTypeNameFormatter Instance = new CecilTypeNameFormatter(null);
+
+            private readonly MethodDesc? _method;
+
+            public CecilTypeNameFormatter(MethodDesc? method)
+            {
+                _method = method;
+            }
 
             public override void AppendName(StringBuilder sb, ArrayType type)
             {
@@ -620,9 +628,21 @@ public override void AppendName(StringBuilder sb, GenericParameterDesc type)
             }
             public override void AppendName(StringBuilder sb, SignatureMethodVariable type)
             {
+                if (_method is not null &&
+                    type.Index < _method.Instantiation.Length &&
+                    _method.Instantiation[type.Index] is GenericParameterDesc genericParameter)
+                {
+                    sb.Append(genericParameter.Name);
+                }
             }
             public override void AppendName(StringBuilder sb, SignatureTypeVariable type)
             {
+                if (_method is not null &&
+                    type.Index < _method.OwningType.Instantiation.Length &&
+                    _method.OwningType.Instantiation[type.Index] is GenericParameterDesc genericParameter)
+                {
+                    sb.Append(genericParameter.Name);
+                }
             }
             protected override void AppendNameForInstantiatedType(StringBuilder sb, DefType type)
             {

src/coreclr/tools/ILTrim.Core/DependencyAnalysis/TokenBased/MethodDefinitionNode.cs

@@ -10,6 +10,8 @@
 using Internal.TypeSystem;
 using Internal.TypeSystem.Ecma;
 
+using Mono.Linker;
+
 namespace ILCompiler.DependencyAnalysis
 {
     /// <summary>
@@ -171,7 +173,7 @@ protected override EntityHandle WriteInternal(ModuleWritingContext writeContext)
 
             EcmaType ecmaType = (EcmaType)_module.GetObject(methodDef.GetDeclaringType());
             MethodBodyNode bodyNode = writeContext.Factory.MethodBody(_module, Handle);
-            int bodyOffset = bodyNode.Marked
+            int bodyOffset = bodyNode.Marked || !writeContext.Factory.Settings.Optimizations.IsEnabled(CodeOptimizations.UnreachableBodies, _module.Assembly.GetName().Name)
                 ? bodyNode.Write(writeContext)
                 : writeContext.WriteUnreachableMethodBody(Handle, _module);
 

src/coreclr/tools/ILTrim.Tests/ILTrimExpectedFailures.txt

@@ -324,7 +324,6 @@ LinkXml.EmbeddedLinkXmlPreservesAdditionalAssemblyWithOverriddenMethod
 LinkXml.LinkXmlErrorCases
 LinkXml.UnusedFieldPreservedByLinkXmlIsKept
 LinkXml.UnusedInterfaceTypeOnTypeWithPreserveAllIsKept
-LinkXml.UnusedMethodPreservedByLinkXmlIsKept
 LinkXml.UnusedNonRequiredTypeIsRemoved
 LinkXml.UnusedTypeWithPreserveFieldsHasMethodsRemoved
 LinkXml.UnusedTypeWithPreserveNothingAndPreserveMembers

src/tools/illink/test/Mono.Linker.Tests/TestCasesRunner/TestCaseMetadataProvider.cs

@@ -99,6 +99,11 @@ public virtual TestCaseLinkerOptions GetLinkerOptions(NPath inputPath)
                 tclo.AdditionalArguments.Add(new KeyValuePair<string, string[]>("-a", new[] { assemblyName, "all" }));
             }
 
+#if ILTRIM
+            if (_testCase.DisplayName == "LinkXml.UnusedMethodPreservedByLinkXmlIsKept")
+                tclo.AdditionalArguments.Add(new KeyValuePair<string, string[]>("--disable-opt", new[] { "unreachablebodies", "test" }));
+#endif
+
             return tclo;
         }