From 5095f1f75f86c2aedaedf9e35457cb6635a3c989 Mon Sep 17 00:00:00 2001
From: Jan Kotas <jkotas@microsoft.com>
Date: Fri, 11 Sep 2020 00:49:34 -0700
Subject: [PATCH] Fix ldtoken for generic RuntimeMethodHandle

ldtoken for generic RuntimeMethodHandle in non-generic method triggered generic dictionary lookup due to normalization of MethodDescs for reflection. It lead to InvalidProgramException later.

Fixes #41674
---
 src/coreclr/src/vm/jitinterface.cpp           |  2 +-
 .../tests/Lambda/LambdaTests.cs               | 18 +++++++
 .../coreclr/GitHub_41674/genericldtoken.il    | 53 +++++++++++++++++++
 .../GitHub_41674/genericldtoken.ilproj        | 10 ++++
 4 files changed, 82 insertions(+), 1 deletion(-)
 create mode 100644 src/tests/Regressions/coreclr/GitHub_41674/genericldtoken.il
 create mode 100644 src/tests/Regressions/coreclr/GitHub_41674/genericldtoken.ilproj

diff --git a/src/coreclr/src/vm/jitinterface.cpp b/src/coreclr/src/vm/jitinterface.cpp
index 37bede3e2dc0d3..8fc0af16a32f51 100644
--- a/src/coreclr/src/vm/jitinterface.cpp
+++ b/src/coreclr/src/vm/jitinterface.cpp
@@ -2629,7 +2629,7 @@ void CEEInfo::embedGenericHandle(
 
         // Runtime lookup is only required for stubs. Regular entrypoints are always the same shared MethodDescs.
         fRuntimeLookup = pMD->IsWrapperStub() &&
-            (pMD->GetMethodTable()->IsSharedByGenericInstantiations() || TypeHandle::IsCanonicalSubtypeInstantiation(methodInst));
+            (th.IsSharedByGenericInstantiations() || TypeHandle::IsCanonicalSubtypeInstantiation(methodInst));
     }
     else
     if (!fEmbedParent && pResolvedToken->hField != NULL)
diff --git a/src/libraries/System.Linq.Expressions/tests/Lambda/LambdaTests.cs b/src/libraries/System.Linq.Expressions/tests/Lambda/LambdaTests.cs
index b6f2d0f71902f5..9cd8d5ef12fda2 100644
--- a/src/libraries/System.Linq.Expressions/tests/Lambda/LambdaTests.cs
+++ b/src/libraries/System.Linq.Expressions/tests/Lambda/LambdaTests.cs
@@ -975,5 +975,23 @@ public void ValidateThatInterpreterWithSimpleTypeUsesDynamicThunk()
             Expression<Func<object, object, object,object>> complexfunc = (object o1, object o2, object o3) => null;
             Assert.True(complexfunc.Compile(preferInterpretation:true).Method.GetType().Name == "RTDynamicMethod");
         }
+
+        private interface IInterface
+        {
+            string B();
+        }
+
+        private readonly struct GenericStruct<T> : IInterface
+        {
+            public string B() => "B";
+        }
+
+        [Fact]
+        public void MethodOnGenericStructImplementingInterface()
+        {
+            Expression<Func<GenericStruct<string>, string>> funcE = x => x.B();
+            Func<GenericStruct<string>, string> f = funcE.Compile();
+            Assert.Equal("B", f(new GenericStruct<string>()));
+        }
     }
 }
diff --git a/src/tests/Regressions/coreclr/GitHub_41674/genericldtoken.il b/src/tests/Regressions/coreclr/GitHub_41674/genericldtoken.il
new file mode 100644
index 00000000000000..245d8b3f973821
--- /dev/null
+++ b/src/tests/Regressions/coreclr/GitHub_41674/genericldtoken.il
@@ -0,0 +1,53 @@
+.assembly extern System.Runtime {  }
+
+.assembly genericldtoken { }
+
+.class public sequential ansi sealed beforefieldinit GenericStruct`1<T>
+       extends [System.Runtime]System.ValueType
+{
+  .pack 0
+  .size 1
+  .custom instance void [System.Runtime]System.Runtime.CompilerServices.IsReadOnlyAttribute::.ctor() = ( 01 00 00 00 ) 
+  .method public hidebysig newslot virtual final 
+          instance string  B() cil managed
+  {
+    // Code size       6 (0x6)
+    .maxstack  8
+    IL_0000:  ldstr      "B"
+    IL_0005:  ret
+  }
+}
+
+.class private auto ansi beforefieldinit Program
+       extends [System.Runtime]System.Object
+{
+  .method private hidebysig static int32 
+          Main(string[] args) cil managed
+  {
+    .entrypoint
+    // Code size       124 (0x7c)
+    .maxstack  5
+    .locals init (valuetype [System.Runtime]System.RuntimeMethodHandle V_0,
+             valuetype [System.Runtime]System.RuntimeMethodHandle V_1)
+    IL_0016:  ldtoken    method instance string valuetype GenericStruct`1<string>::B()
+              stloc.0
+
+    IL_0053:  ldtoken    valuetype GenericStruct`1<string>
+    IL_0058:  call       class [System.Runtime]System.Type [System.Runtime]System.Type::GetTypeFromHandle(valuetype [System.Runtime]System.RuntimeTypeHandle)
+    IL_005d:  ldstr      "B"
+    IL_0062:  call       instance class [System.Runtime]System.Reflection.MethodInfo [System.Runtime]System.Type::GetMethod(string)
+    IL_0067:  callvirt   instance valuetype [System.Runtime]System.RuntimeMethodHandle [System.Runtime]System.Reflection.MethodBase::get_MethodHandle()
+    IL_006c:  stloc.1
+
+    IL_006d:  ldloca.s   V_0
+    IL_006f:  ldloc.1
+    IL_0070:  call       instance bool [System.Runtime]System.RuntimeMethodHandle::Equals(valuetype [System.Runtime]System.RuntimeMethodHandle)
+    IL_0075:  brtrue.s   IL_0079
+
+    IL_0077:  ldc.i4.m1
+    IL_0078:  ret
+
+    IL_0079:  ldc.i4.s   100
+    IL_007b:  ret
+  }
+}
diff --git a/src/tests/Regressions/coreclr/GitHub_41674/genericldtoken.ilproj b/src/tests/Regressions/coreclr/GitHub_41674/genericldtoken.ilproj
new file mode 100644
index 00000000000000..6bfc8a43251cfc
--- /dev/null
+++ b/src/tests/Regressions/coreclr/GitHub_41674/genericldtoken.ilproj
@@ -0,0 +1,10 @@
+<Project Sdk="Microsoft.NET.Sdk.IL">
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <CLRTestKind>BuildAndRun</CLRTestKind>
+    <CLRTestPriority>0</CLRTestPriority>
+  </PropertyGroup>
+  <ItemGroup>
+    <Compile Include="genericldtoken.il" />
+  </ItemGroup>
+</Project>