Constraint checking (#20)

Author: davidwrighton

src/coreclr/vm/typedesc.cpp

@@ -1903,6 +1903,30 @@ BOOL TypeVarTypeDesc::SatisfiesConstraints(SigTypeContext *pTypeContextOfConstra
                     // if a concrete type can be cast to the constraint, then this constraint will be satisifed
                     if (thElem.CanCastTo(thConstraint))
                     {
+                        // Static virtual methods need an extra check when an abstract type is used for instantiation
+                        // to ensure that the implementation of the constraint is complete
+                        if (!thElem.IsTypeDesc() &&
+                            thElem.AsMethodTable()->IsAbstract() &&
+                            thConstraint.IsInterface() &&
+                            thConstraint.AsMethodTable()->HasVirtualStaticMethods())
+                        {
+                            MethodTable *pInterfaceMT = thConstraint.AsMethodTable();
+                            bool virtualStaticResolutionCheckFailed = false;
+                            for (MethodTable::MethodIterator it(pInterfaceMT); it.IsValid(); it.Next())
+                            {
+                                MethodDesc *pMD = it.GetMethodDesc();
+                                if (pMD->IsVirtual() &&
+                                    pMD->IsStatic() &&
+                                    !thElem.AsMethodTable()->ResolveVirtualStaticMethod(pInterfaceMT, pMD, /* allowNullResult */ TRUE, /* checkDuplicates */ TRUE))
+                                {
+                                    virtualStaticResolutionCheckFailed = true;
+                                    break;
+                                }
+                            }
+
+                            if (virtualStaticResolutionCheckFailed)
+                                continue;
+                        }
                         fCanCast = TRUE;
                         break;
                     }

src/tests/Loader/classloader/StaticVirtualMethods/NegativeTestCases/UnimplementedAbstractMethodOnAbstractClass.il

@@ -131,14 +131,14 @@ ConstrainedCallOnAbstractClassToAbstractMethodOnSharedGenericDone: nop
     .try {
         call void TestEntrypoint::TestScenario2Wrapper()
         ldstr "ConstraintCheckShouldFail"
-        ldstr "TypeLoadException"
+        ldstr "VerificationException"
         ldstr "Did not throw exception"
         call void [TypeHierarchyCommonCs]Statics::CheckForFailure(string,string,string)
         leave.s ConstraintCheckShouldFailDone
     } catch [System.Runtime]System.Exception {
         stloc.0
         ldstr "ConstraintCheckShouldFail"
-        ldstr "TypeLoadException"
+        ldstr "VerificationException"
         ldloc.0
         callvirt   instance class [System.Runtime]System.Type [System.Runtime]System.Exception::GetType()
         callvirt   instance string [System.Runtime]System.Reflection.MemberInfo::get_Name()