Add support for default implementation of static virtuals with method constraints

src/coreclr/inc/enum_class_flags.h

@@ -0,0 +1,52 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+#ifndef ENUM_CLASS_FLAGS_OPERATORS
+#define ENUM_CLASS_FLAGS_OPERATORS
+
+template <typename T>
+inline constexpr auto operator& (T left, T right) -> decltype(T::support_use_as_flags)
+{
+    return static_cast<T>(static_cast<int>(left) & static_cast<int>(right));
+}
+
+template <typename T>
+inline constexpr auto operator| (T left, T right) -> decltype(T::support_use_as_flags)
+{
+    return static_cast<T>(static_cast<int>(left) & static_cast<int>(right));
+}
+
+template <typename T>
+inline constexpr auto operator^ (T left, T right) -> decltype(T::support_use_as_flags)
+{
+    return static_cast<T>(static_cast<int>(left) & static_cast<int>(right));
+}
+
+template <typename T>
+inline constexpr auto operator~ (T value) -> decltype(T::support_use_as_flags)
+{
+    return static_cast<T>(~static_cast<int>(value));
+}
+
+template <typename T>
+inline constexpr auto operator |= (T& left, T right) -> const decltype(T::support_use_as_flags)&
+{
+    left = left | right;
+    return left;
+}
+
+template <typename T>
+inline constexpr auto operator &= (T& left, T right) -> const decltype(T::support_use_as_flags)&
+{
+    left = left | right;
+    return left;
+}
+
+template <typename T>
+inline constexpr auto operator ^= (T& left, T right) -> const decltype(T::support_use_as_flags)&
+{
+    left = left | right;
+    return left;
+}
+
+#endif /* ENUM_CLASS_FLAGS_OPERATORS */

src/coreclr/vm/genericdict.cpp

@@ -1144,9 +1144,9 @@ Dictionary::PopulateEntry(
                     pResolvedMD = constraintType.GetMethodTable()->ResolveVirtualStaticMethod(
                         ownerType.GetMethodTable(),
                         pMethod,
-                        /* allowNullResult */ TRUE,
-                        /* verifyImplemented */ FALSE,
-                        /* allowVariantMatches */ TRUE,
+                        ResolveVirtualStaticMethodFlags::AllowNullResult |
+                        ResolveVirtualStaticMethodFlags::AllowVariantMatches |
+                        ResolveVirtualStaticMethodFlags::InstantiateResultOverFinalMethodDesc,
                         &uniqueResolution);
 
                     // If we couldn't get an exact result, fall back to using a stub to make the exact function call

src/coreclr/vm/methodtable.cpp

@@ -6210,22 +6210,26 @@ MethodTable::FindDispatchImpl(
 
                 // Try exact match first
                 MethodDesc *pDefaultMethod = NULL;
+
+                FindDefaultInterfaceImplementationFlags flags = FindDefaultInterfaceImplementationFlags::InstantiateFoundMethodDesc;
+                if (throwOnConflict)
+                    flags = flags | FindDefaultInterfaceImplementationFlags::ThrowOnConflict;
+
                 BOOL foundDefaultInterfaceImplementation  = FindDefaultInterfaceImplementation(
                     pIfcMD,     // the interface method being resolved
                     pIfcMT,     // the interface being resolved
                     &pDefaultMethod,
-                    FALSE, // allowVariance
-                    throwOnConflict);
+                    flags);
 
                 // If there's no exact match, try a variant match
                 if (!foundDefaultInterfaceImplementation && pIfcMT->HasVariance())
                 {
+                    flags = flags | FindDefaultInterfaceImplementationFlags::AllowVariance;
                     foundDefaultInterfaceImplementation = FindDefaultInterfaceImplementation(
                         pIfcMD,     // the interface method being resolved
                         pIfcMT,     // the interface being resolved
                         &pDefaultMethod,
-                        TRUE, // allowVariance
-                        throwOnConflict);
+                        flags);
                 }
 
                 if (foundDefaultInterfaceImplementation)
@@ -6324,10 +6328,13 @@ namespace
         MethodTable *pMT,
         MethodDesc *interfaceMD,
         MethodTable *interfaceMT,
-        BOOL allowVariance,
+        FindDefaultInterfaceImplementationFlags findDefaultImplementationFlags,
         MethodDesc **candidateMD,
         ClassLoadLevel level)
     {
+        bool allowVariance = (findDefaultImplementationFlags & FindDefaultInterfaceImplementationFlags::AllowVariance) != FindDefaultInterfaceImplementationFlags::None;
+        bool instantiateMethodInstantiation = (findDefaultImplementationFlags & FindDefaultInterfaceImplementationFlags::InstantiateFoundMethodDesc) != FindDefaultInterfaceImplementationFlags::None;
+
         *candidateMD = NULL;
 
         MethodDesc *candidateMaybe = NULL;
@@ -6418,11 +6425,20 @@ namespace
             else
             {
                 // Static virtual methods don't record MethodImpl slots so they need special handling
+                ResolveVirtualStaticMethodFlags resolveVirtualStaticMethodFlags = ResolveVirtualStaticMethodFlags::None;
+                if (allowVariance)
+                {
+                    resolveVirtualStaticMethodFlags |= ResolveVirtualStaticMethodFlags::AllowVariantMatches;
+                }
+                if (instantiateMethodInstantiation)
+                {
+                    resolveVirtualStaticMethodFlags |= ResolveVirtualStaticMethodFlags::InstantiateResultOverFinalMethodDesc;
+                }
+
                 candidateMaybe = pMT->TryResolveVirtualStaticMethodOnThisType(
                     interfaceMT,
                     interfaceMD,
-                    /* verifyImplemented */ FALSE,
-                    /* allowVariance */ allowVariance,
+                    resolveVirtualStaticMethodFlags,
                     /* level */ level);
             }
         }
@@ -6461,8 +6477,7 @@ BOOL MethodTable::FindDefaultInterfaceImplementation(
     MethodDesc *pInterfaceMD,
     MethodTable *pInterfaceMT,
     MethodDesc **ppDefaultMethod,
-    BOOL allowVariance,
-    BOOL throwOnConflict,
+    FindDefaultInterfaceImplementationFlags findDefaultImplementationFlags,
     ClassLoadLevel level
 )
 {
@@ -6478,12 +6493,13 @@ BOOL MethodTable::FindDefaultInterfaceImplementation(
     } CONTRACT_END;
 
 #ifdef FEATURE_DEFAULT_INTERFACES
+    bool allowVariance = (findDefaultImplementationFlags & FindDefaultInterfaceImplementationFlags::AllowVariance) != FindDefaultInterfaceImplementationFlags::None;
     CQuickArray<MatchCandidate> candidates;
     unsigned candidatesCount = 0;
 
     // Check the current method table itself
     MethodDesc *candidateMaybe = NULL;
-    if (IsInterface() && TryGetCandidateImplementation(this, pInterfaceMD, pInterfaceMT, allowVariance, &candidateMaybe, level))
+    if (IsInterface() && TryGetCandidateImplementation(this, pInterfaceMD, pInterfaceMT, findDefaultImplementationFlags, &candidateMaybe, level))
     {
         _ASSERTE(candidateMaybe != NULL);
 
@@ -6523,7 +6539,7 @@ BOOL MethodTable::FindDefaultInterfaceImplementation(
                 MethodTable *pCurMT = it.GetInterface(pMT, level);
 
                 MethodDesc *pCurMD = NULL;
-                if (TryGetCandidateImplementation(pCurMT, pInterfaceMD, pInterfaceMT, allowVariance, &pCurMD, level))
+                if (TryGetCandidateImplementation(pCurMT, pInterfaceMD, pInterfaceMT, findDefaultImplementationFlags, &pCurMD, level))
                 {
                     //
                     // Found a match. But is it a more specific match (we want most specific interfaces)
@@ -6619,6 +6635,8 @@ BOOL MethodTable::FindDefaultInterfaceImplementation(
         }
         else if (pBestCandidateMT != candidates[i].pMT)
         {
+            bool throwOnConflict = (findDefaultImplementationFlags & FindDefaultInterfaceImplementationFlags::ThrowOnConflict) != FindDefaultInterfaceImplementationFlags::None;
+
             if (throwOnConflict)
                 ThrowExceptionForConflictingOverride(this, pInterfaceMT, pInterfaceMD);
 
@@ -8875,12 +8893,15 @@ MethodDesc *
 MethodTable::ResolveVirtualStaticMethod(
     MethodTable* pInterfaceType,
     MethodDesc* pInterfaceMD,
-    BOOL allowNullResult,
-    BOOL verifyImplemented,
-    BOOL allowVariantMatches,
+    ResolveVirtualStaticMethodFlags resolveVirtualStaticMethodFlags,
     BOOL* uniqueResolution,
     ClassLoadLevel level)
 {
+    bool verifyImplemented = (resolveVirtualStaticMethodFlags & ResolveVirtualStaticMethodFlags::VerifyImplemented) != ResolveVirtualStaticMethodFlags::None;
+    bool allowVariantMatches = (resolveVirtualStaticMethodFlags & ResolveVirtualStaticMethodFlags::AllowVariantMatches) != ResolveVirtualStaticMethodFlags::None;
+    bool instantiateMethodParameters = (resolveVirtualStaticMethodFlags & ResolveVirtualStaticMethodFlags::InstantiateResultOverFinalMethodDesc) != ResolveVirtualStaticMethodFlags::None;
+    bool allowNullResult = (resolveVirtualStaticMethodFlags & ResolveVirtualStaticMethodFlags::AllowNullResult) != ResolveVirtualStaticMethodFlags::None;
+
     if (uniqueResolution != nullptr)
     {
         *uniqueResolution = TRUE;
@@ -8912,7 +8933,7 @@ MethodTable::ResolveVirtualStaticMethod(
             // Search for match on a per-level in the type hierarchy
             for (MethodTable* pMT = this; pMT != nullptr; pMT = pMT->GetParentMethodTable())
             {
-                MethodDesc* pMD = pMT->TryResolveVirtualStaticMethodOnThisType(pInterfaceType, pInterfaceMD, verifyImplemented, /*allowVariance*/ FALSE, level);
+                MethodDesc* pMD = pMT->TryResolveVirtualStaticMethodOnThisType(pInterfaceType, pInterfaceMD, resolveVirtualStaticMethodFlags & ~ResolveVirtualStaticMethodFlags::AllowVariantMatches, level);
                 if (pMD != nullptr)
                 {
                     return pMD;
@@ -8956,7 +8977,7 @@ MethodTable::ResolveVirtualStaticMethod(
                         {
                             // Variant or equivalent matching interface found
                             // Attempt to resolve on variance matched interface
-                            pMD = pMT->TryResolveVirtualStaticMethodOnThisType(pItfInMap, pInterfaceMD, verifyImplemented, /*allowVariance*/ FALSE, level);
+                            pMD = pMT->TryResolveVirtualStaticMethodOnThisType(pItfInMap, pInterfaceMD, resolveVirtualStaticMethodFlags & ~ResolveVirtualStaticMethodFlags::AllowVariantMatches, level);
                             if (pMD != nullptr)
                             {
                                 return pMD;
@@ -8970,12 +8991,25 @@ MethodTable::ResolveVirtualStaticMethod(
             BOOL allowVariantMatchInDefaultImplementationLookup = FALSE;
             do
             {
+                FindDefaultInterfaceImplementationFlags findDefaultImplementationFlags = FindDefaultInterfaceImplementationFlags::None;
+                if (allowVariantMatchInDefaultImplementationLookup)
+                {
+                    findDefaultImplementationFlags |= FindDefaultInterfaceImplementationFlags::AllowVariance;
+                }
+                if (uniqueResolution == nullptr)
+                {
+                    findDefaultImplementationFlags |= FindDefaultInterfaceImplementationFlags::ThrowOnConflict;
+                }
+                if (instantiateMethodParameters)
+                {
+                    findDefaultImplementationFlags |= FindDefaultInterfaceImplementationFlags::InstantiateFoundMethodDesc;
+                }
+
                 BOOL haveUniqueDefaultImplementation = FindDefaultInterfaceImplementation(
                     pInterfaceMD,
                     pInterfaceType,
                     &pMDDefaultImpl,
-                    /* allowVariance */ allowVariantMatchInDefaultImplementationLookup,
-                    /* throwOnConflict */ uniqueResolution == nullptr,
+                    findDefaultImplementationFlags,
                     level);
                 if (haveUniqueDefaultImplementation || (pMDDefaultImpl != nullptr && (verifyImplemented || uniqueResolution != nullptr)))
                 {
@@ -9018,8 +9052,12 @@ MethodTable::ResolveVirtualStaticMethod(
 // Try to locate the appropriate MethodImpl matching a given interface static virtual method.
 // Returns nullptr on failure.
 MethodDesc*
-MethodTable::TryResolveVirtualStaticMethodOnThisType(MethodTable* pInterfaceType, MethodDesc* pInterfaceMD, BOOL verifyImplemented, BOOL allowVariance, ClassLoadLevel level)
+MethodTable::TryResolveVirtualStaticMethodOnThisType(MethodTable* pInterfaceType, MethodDesc* pInterfaceMD, ResolveVirtualStaticMethodFlags resolveVirtualStaticMethodFlags, ClassLoadLevel level)
 {
+    bool instantiateMethodParameters = (resolveVirtualStaticMethodFlags & ResolveVirtualStaticMethodFlags::InstantiateResultOverFinalMethodDesc) != ResolveVirtualStaticMethodFlags::None;
+    bool allowVariance = (resolveVirtualStaticMethodFlags & ResolveVirtualStaticMethodFlags::AllowVariantMatches) != ResolveVirtualStaticMethodFlags::None;
+    bool verifyImplemented = (resolveVirtualStaticMethodFlags & ResolveVirtualStaticMethodFlags::VerifyImplemented) != ResolveVirtualStaticMethodFlags::None;
+
     HRESULT hr = S_OK;
     IMDInternalImport* pMDInternalImport = GetMDImport();
     HENUMInternalMethodImplHolder hEnumMethodImpl(pMDInternalImport);
@@ -9148,7 +9186,7 @@ MethodTable::TryResolveVirtualStaticMethodOnThisType(MethodTable* pInterfaceType
             COMPlusThrow(kTypeLoadException, E_FAIL);
         }
 
-        if (!verifyImplemented)
+        if (!verifyImplemented && instantiateMethodParameters)
         {
             pMethodImpl = pMethodImpl->FindOrCreateAssociatedMethodDesc(
                 pMethodImpl,
@@ -9202,9 +9240,7 @@ MethodTable::VerifyThatAllVirtualStaticMethodsAreImplemented()
                     !ResolveVirtualStaticMethod(
                         pInterfaceMT,
                         pMD,
-                        /* allowNullResult */ TRUE,
-                        /* verifyImplemented */ TRUE,
-                        /* allowVariantMatches */ FALSE,
+                        ResolveVirtualStaticMethodFlags::AllowNullResult | ResolveVirtualStaticMethodFlags::VerifyImplemented,
                         /* uniqueResolution */ &uniqueResolution,
                         /* level */ CLASS_LOAD_EXACTPARENTS)))
                 {
@@ -9240,12 +9276,18 @@ MethodTable::TryResolveConstraintMethodApprox(
         _ASSERTE(!thInterfaceType.IsTypeDesc());
         _ASSERTE(thInterfaceType.IsInterface());
         BOOL uniqueResolution;
+
+        ResolveVirtualStaticMethodFlags flags = ResolveVirtualStaticMethodFlags::AllowVariantMatches 
+                                              | ResolveVirtualStaticMethodFlags::InstantiateResultOverFinalMethodDesc;
+        if (pfForceUseRuntimeLookup != NULL)
+        {
+            flags |= ResolveVirtualStaticMethodFlags::AllowNullResult;
+        }
+
         MethodDesc *result = ResolveVirtualStaticMethod(
             thInterfaceType.GetMethodTable(),
             pInterfaceMD,
-            /* allowNullResult */pfForceUseRuntimeLookup != NULL,
-            /* verifyImplemented */ FALSE,
-            /* allowVariantMatches */ TRUE,
+            flags,
             &uniqueResolution);
         if (result == NULL || !uniqueResolution)
         {

src/coreclr/vm/methodtable.h

@@ -25,6 +25,7 @@
 #include "contractimpl.h"
 #include "generics.h"
 #include "gcinfotypes.h"
+#include "enum_class_flags.h"
 
 /*
  * Forward Declarations
@@ -63,6 +64,28 @@ class ClassFactoryBase;
 class ArgDestination;
 enum class WellKnownAttribute : DWORD;
 
+enum class ResolveVirtualStaticMethodFlags
+{
+    None = 0,
+    AllowNullResult = 1,
+    VerifyImplemented = 2,
+    AllowVariantMatches = 4,
+    InstantiateResultOverFinalMethodDesc = 8,
+
+    support_use_as_flags // Enable the template functions in enum_class_flags.h
+};
+
+
+enum class FindDefaultInterfaceImplementationFlags
+{
+    None,
+    AllowVariance = 1,
+    ThrowOnConflict = 2,
+    InstantiateFoundMethodDesc = 4,
+
+    support_use_as_flags // Enable the template functions in enum_class_flags.h
+};
+
 //============================================================================
 // This is the in-memory structure of a class and it will evolve.
 //============================================================================
@@ -2084,7 +2107,6 @@ class MethodTable
     MethodDesc *GetMethodDescForComInterfaceMethod(MethodDesc *pItfMD, bool fNullOk);
 #endif // FEATURE_COMINTEROP
 
-
     // Resolve virtual static interface method pInterfaceMD on this type.
     //
     // Specify allowNullResult to return NULL instead of throwing if the there is no implementation
@@ -2096,9 +2118,7 @@ class MethodTable
     MethodDesc *ResolveVirtualStaticMethod(
         MethodTable* pInterfaceType,
         MethodDesc* pInterfaceMD,
-        BOOL allowNullResult,
-        BOOL verifyImplemented = FALSE,
-        BOOL allowVariantMatches = TRUE,
+        ResolveVirtualStaticMethodFlags resolveVirtualStaticMethodFlags,
         BOOL *uniqueResolution = NULL,
         ClassLoadLevel level = CLASS_LOADED);
 
@@ -2178,8 +2198,7 @@ class MethodTable
         MethodDesc *pInterfaceMD,
         MethodTable *pObjectMT,
         MethodDesc **ppDefaultMethod,
-        BOOL allowVariance,
-        BOOL throwOnConflict,
+        FindDefaultInterfaceImplementationFlags findDefaultImplementationFlags,
         ClassLoadLevel level = CLASS_LOADED);
 #endif // DACCESS_COMPILE
 
@@ -2219,7 +2238,7 @@ class MethodTable
 
     // Try to resolve a given static virtual method override on this type. Return nullptr
     // when not found.
-    MethodDesc *TryResolveVirtualStaticMethodOnThisType(MethodTable* pInterfaceType, MethodDesc* pInterfaceMD, BOOL verifyImplemented, BOOL allowVariance, ClassLoadLevel level);
+    MethodDesc *TryResolveVirtualStaticMethodOnThisType(MethodTable* pInterfaceType, MethodDesc* pInterfaceMD, ResolveVirtualStaticMethodFlags resolveVirtualStaticMethodFlags, ClassLoadLevel level);
 
 public:
     static MethodDesc *MapMethodDeclToMethodImpl(MethodDesc *pMDDecl);

src/coreclr/vm/runtimehandles.cpp

@@ -1102,9 +1102,8 @@ extern "C" MethodDesc* QCALLTYPE RuntimeTypeHandle_GetInterfaceMethodImplementat
         pResult = typeHandle.GetMethodTable()->ResolveVirtualStaticMethod(
             thOwnerOfMD.GetMethodTable(),
             pMD,
-            /* allowNullResult */ TRUE,
-            /* verifyImplemented*/ FALSE,
-            /* allowVariantMatches */ TRUE);
+            ResolveVirtualStaticMethodFlags::AllowNullResult |
+            ResolveVirtualStaticMethodFlags::AllowVariantMatches);
     }
     else
     {

src/coreclr/vm/typedesc.cpp

@@ -1611,8 +1611,9 @@ BOOL TypeVarTypeDesc::SatisfiesConstraints(SigTypeContext *pTypeContextOfConstra
                                 if (pMD->IsVirtual() &&
                                     pMD->IsStatic() &&
                                     (pMD->IsAbstract() && !thElem.AsMethodTable()->ResolveVirtualStaticMethod(
-                                        pInterfaceMT, pMD, /* allowNullResult */ TRUE, /* verifyImplemented */ TRUE,
-                                        /*allowVariantMatches*/ TRUE, /*uniqueResolution*/ NULL, CLASS_DEPENDENCIES_LOADED)))
+                                        pInterfaceMT, pMD,
+                                        ResolveVirtualStaticMethodFlags::AllowNullResult | ResolveVirtualStaticMethodFlags::VerifyImplemented | ResolveVirtualStaticMethodFlags::AllowVariantMatches,
+                                        /*uniqueResolution*/ NULL, CLASS_DEPENDENCIES_LOADED)))
                                 {
                                     virtualStaticResolutionCheckFailed = true;
                                     break;