swiftlang · Azoy · Oct 10, 2023 · Oct 9, 2023
@@ -2846,17 +2846,29 @@ const Metadata *swift::_swift_instantiateCheckedGenericMetadata(
     return nullptr;
   }
 
-  DemanglerForRuntimeTypeResolution<StackAllocatedDemangler<2048>> demangler;
+  llvm::SmallVector<const void *, 8> extraArguments;
 
-  llvm::ArrayRef<MetadataOrPack> genericArgsRef(
-      reinterpret_cast<const MetadataOrPack *>(genericArgs), genericArgsSize);
-  llvm::SmallVector<unsigned, 8> genericParamCounts;
-  llvm::SmallVector<const void *, 8> allGenericArgs;
+  for (size_t i = 0; i != genericArgsSize; i += 1) {
+    extraArguments.push_back(genericArgs[i]);
+  }
 
-  auto result = _gatherGenericParameters(context, genericArgsRef,
-                                         /* parent */ nullptr,
-                                         genericParamCounts, allGenericArgs,
-                                         demangler);
+  // Check whether the generic requirements are satisfied, collecting
+  // any extra arguments we need for the instantiation function.
+  //
+  // Note: The extra arguemnts provided are not complete and do not include
+  // witness tables. This is fine for _checkGenericRequirements because it does
+  // not look for any of those.
+  SubstGenericParametersFromMetadata substitutions(context, extraArguments.data());
+
+  auto result = _checkGenericRequirements(
+      context->getGenericContext()->getGenericRequirements(), extraArguments,
+      [&substitutions](unsigned depth, unsigned index) {
+        return substitutions.getMetadata(depth, index).Ptr;
+      },
+      [](const Metadata *type, unsigned index) {
+        // In fact, just don't offer any witness tables if asked for one.
+        return nullptr;
+      }, /* allowsUnresolvedSubject */ true);
 
   // _gatherGenericParameters returns llvm::None on success.
   if (result.hasValue()) {
@@ -2865,7 +2877,7 @@ const Metadata *swift::_swift_instantiateCheckedGenericMetadata(
 
   auto accessFunction = context->getAccessFunction();
 
-  return accessFunction(MetadataState::Complete, allGenericArgs).Value;
+  return accessFunction(MetadataState::Complete, extraArguments).Value;
 }
 
 #if SWIFT_OBJC_INTEROP

@@ -523,7 +523,8 @@ class TypeInfo {
       llvm::ArrayRef<GenericRequirementDescriptor> requirements,
       llvm::SmallVectorImpl<const void *> &extraArguments,
       SubstGenericParameterFn substGenericParam,
-      SubstDependentWitnessTableFn substWitnessTable);
+      SubstDependentWitnessTableFn substWitnessTable,
+      bool allowsUnresolvedSubject = false);
 
   /// A helper function which avoids performing a store if the destination
   /// address already contains the source value.  This is useful when

@@ -1344,24 +1344,37 @@ static llvm::Optional<TypeLookupError>
 checkGenericRequirement(const GenericRequirementDescriptor &req,
                         llvm::SmallVectorImpl<const void *> &extraArguments,
                         SubstGenericParameterFn substGenericParam,
-                        SubstDependentWitnessTableFn substWitnessTable) {
+                        SubstDependentWitnessTableFn substWitnessTable,
+                        bool allowsUnresolvedSubject) {
   assert(!req.getFlags().isPackRequirement());
 
   // Make sure we understand the requirement we're dealing with.
   if (!req.hasKnownKind())
     return TypeLookupError("unknown kind");
 
+  const Metadata *subjectType = nullptr;
+
   // Resolve the subject generic parameter.
   auto result = swift_getTypeByMangledName(
       MetadataState::Abstract, req.getParam(), extraArguments.data(),
       substGenericParam, substWitnessTable);
-  if (result.getError())
+
+  if (!allowsUnresolvedSubject && result.isError()) {
     return *result.getError();
-  const Metadata *subjectType = result.getType().getMetadata();
+  }
+
+  if (!result.isError()) {
+    subjectType = result.getType().getMetadata();
+  }
 
   // Check the requirement.
   switch (req.getKind()) {
   case GenericRequirementKind::Protocol: {
+    // Protocol requirements _require_ a subject type.
+    if (result.isError()) {
+      return *result.getError();
+    }
+
     const WitnessTable *witnessTable = nullptr;
     if (!_conformsToProtocol(nullptr, subjectType, req.getProtocol(),
                              &witnessTable)) {
@@ -1382,16 +1395,37 @@ checkGenericRequirement(const GenericRequirementDescriptor &req,
   }
 
   case GenericRequirementKind::SameType: {
+    // Same type requirements don't require a valid subject.
+
+    const Metadata *sameType = nullptr;
+
     // Demangle the second type under the given substitutions.
     auto result = swift_getTypeByMangledName(
         MetadataState::Abstract, req.getMangledTypeName(),
         extraArguments.data(), substGenericParam, substWitnessTable);
-    if (result.getError())
+
+    if (!allowsUnresolvedSubject && result.isError()) {
       return *result.getError();
-    auto otherType = result.getType().getMetadata();
+    }
+
+    if (!result.isError()) {
+      sameType = result.getType().getMetadata();
+    }
+
+    // If we don't have one of either the subject type or the same type and we
+    // have the other, then return this as a success. This assumes the given
+    // extra arguments have provided only the required key arguments in which
+    // case some same type constraints may concretize some generic arguments
+    // making them non-key.
+    //
+    // Note: We don't need to check for allowsUnresolvedSubject here because
+    // these can only be null in the case where we do allow it.
+    if ((!subjectType && sameType) || (subjectType && !sameType)) {
+      return llvm::None;
+    }
 
     // Check that the types are equivalent.
-    if (subjectType != otherType) {
+    if (subjectType != sameType) {
       return TYPE_LOOKUP_ERROR_FMT(
           "subject type %.*s does not match %.*s", (int)req.getParam().size(),
           req.getParam().data(), (int)req.getMangledTypeName().size(),
@@ -1402,10 +1436,20 @@ checkGenericRequirement(const GenericRequirementDescriptor &req,
   }
 
   case GenericRequirementKind::Layout: {
+    // Layout requirements _require_ a subject type.
+    if (result.isError()) {
+      return *result.getError();
+    }
+
     return satisfiesLayoutConstraint(req, subjectType);
   }
 
   case GenericRequirementKind::BaseClass: {
+    // Base class requirements _require_ a subject type.
+    if (result.isError()) {
+      return *result.getError();
+    }
+
     // Demangle the base type under the given substitutions.
     auto result = swift_getTypeByMangledName(
         MetadataState::Abstract, req.getMangledTypeName(),
@@ -1594,7 +1638,8 @@ llvm::Optional<TypeLookupError> swift::_checkGenericRequirements(
     llvm::ArrayRef<GenericRequirementDescriptor> requirements,
     llvm::SmallVectorImpl<const void *> &extraArguments,
     SubstGenericParameterFn substGenericParam,
-    SubstDependentWitnessTableFn substWitnessTable) {
+    SubstDependentWitnessTableFn substWitnessTable,
+    bool allowsUnresolvedSubject) {
   for (const auto &req : requirements) {
     if (req.getFlags().isPackRequirement()) {
       auto error = checkGenericPackRequirement(req, extraArguments,
@@ -1605,7 +1650,8 @@ llvm::Optional<TypeLookupError> swift::_checkGenericRequirements(
     } else {
       auto error = checkGenericRequirement(req, extraArguments,
                                            substGenericParam,
-                                           substWitnessTable);
+                                           substWitnessTable,
+                                           allowsUnresolvedSubject);
       if (error)
         return error;
     }

@@ -30,7 +30,7 @@ func metaPointer(_ x: Any.Type) -> UnsafeRawPointer {
   unsafeBitCast(x, to: UnsafeRawPointer.self)
 }
 
-testSuite.test("_swift_checkedCreateType non-variadic") {
+testSuite.test("_swift_instantiateCheckedGenericMetadata non-variadic") {
   let dictMeta = unsafeBitCast(
     [Int: Int].self as Any.Type,
     to: UnsafeRawPointer.self
@@ -53,7 +53,7 @@ testSuite.test("_swift_checkedCreateType non-variadic") {
   }
 }
 
-testSuite.test("_swift_checkedCreateType variadic") {
+testSuite.test("_swift_instantiateCheckedGenericMetadata variadic") {
   let variMeta = unsafeBitCast(
     Variadic< >.self as Any.Type,
     to: UnsafeRawPointer.self
@@ -70,7 +70,9 @@ testSuite.test("_swift_checkedCreateType variadic") {
       UnsafeRawPointer(pack.baseAddress!),
       UInt(pack.count)
     )
-    let genericArgs = [packPointer]
+
+    // The 3 is the shape of the pack
+    let genericArgs = [UnsafeRawPointer(bitPattern: 3)!, packPointer]
 
     genericArgs.withUnsafeBufferPointer { genericArgs in
       let newVari = _instantiateCheckedGenericMetadata(
@@ -84,7 +86,7 @@ testSuite.test("_swift_checkedCreateType variadic") {
   }
 }
 
-testSuite.test("_swift_checkedCreateType variadic nested with requirements") {
+testSuite.test("_swift_instantiateCheckedGenericMetadata variadic nested with requirements") {
   let nestedMeta = unsafeBitCast(
     Variadic< >.Nested<()>.self as Any.Type,
     to: UnsafeRawPointer.self
@@ -101,6 +103,10 @@ testSuite.test("_swift_checkedCreateType variadic nested with requirements") {
   nestedPack.withUnsafeBufferPointer { nestedPack in
     variPack.withUnsafeBufferPointer { variPack in
       let nestedGenericArgs = [
+        // First shape class
+        UnsafeRawPointer(bitPattern: 3)!,
+        // Second shape class
+        UnsafeRawPointer(bitPattern: 3)!,
         allocateMetadataPack(
           UnsafeRawPointer(variPack.baseAddress!),
           UInt(variPack.count)
@@ -126,4 +132,53 @@ testSuite.test("_swift_checkedCreateType variadic nested with requirements") {
   }
 }
 
+struct Generic<T> {}
+struct Generic2<T, U> {}
+
+extension Generic where T == Int {
+  struct Nested {}
+}
+
+extension Generic2 where T == U? {
+  struct Nested {}
+}
+
+testSuite.test("_swift_instantiateCheckedGenericMetadata concrete generic types (same type conretized)") {
+  let nestedMeta1 = metaPointer(Generic<Int>.Nested.self)
+  let nestedDesc1 = nestedMeta1.load(
+    fromByteOffset: MemoryLayout<Int>.size,
+    as: UnsafeRawPointer.self
+  )
+
+  let genericArgs1: [UnsafeRawPointer?] = []
+
+  genericArgs1.withUnsafeBufferPointer {
+    let nested = _instantiateCheckedGenericMetadata(
+      nestedDesc1,
+      UnsafeRawPointer($0.baseAddress!),
+      UInt($0.count)
+    )
+
+    expectTrue(nested == Generic<Int>.Nested.self)
+  }
+
+  let nestedMeta2 = metaPointer(Generic2<Int?, Int>.Nested.self)
+  let nestedDesc2 = nestedMeta2.load(
+    fromByteOffset: MemoryLayout<Int>.size,
+    as: UnsafeRawPointer.self
+  )
+
+  let genericArgs2 = [metaPointer(String.self)]
+
+  genericArgs2.withUnsafeBufferPointer {
+    let nested = _instantiateCheckedGenericMetadata(
+      nestedDesc2,
+      UnsafeRawPointer($0.baseAddress!),
+      UInt($0.count)
+    )
+
+    expectTrue(nested == Generic2<String?, String>.Nested.self)
+  }
+}
+
 runAllTests()