Merge pull request #15860 from slavapestov/fix-foreign-class-bug

Fix miscompile when emitting protocol conformance of a runtime-only class

Author: slavapestov

lib/IRGen/GenMeta.cpp

@@ -3348,7 +3348,7 @@ IRGenModule::getAddrOfForeignTypeMetadataCandidate(CanType type) {
   if (auto classType = dyn_cast<ClassType>(type)) {
     assert(!classType.getParent());
     auto classDecl = classType->getDecl();
-    assert(classDecl->isForeign());
+    assert(classDecl->getForeignClassKind() == ClassDecl::ForeignKind::CFType);
 
     ForeignClassMetadataBuilder builder(*this, classDecl, init);
     builder.layout();
@@ -3389,7 +3389,8 @@ IRGenModule::getAddrOfForeignTypeMetadataCandidate(CanType type) {
   if (auto enclosing = type->getNominalParent()) {
     auto canonicalEnclosing = enclosing->getCanonicalType();
     if (requiresForeignTypeMetadata(canonicalEnclosing)) {
-      getAddrOfForeignTypeMetadataCandidate(canonicalEnclosing);
+      (void)getTypeMetadataAccessFunction(*this, canonicalEnclosing,
+                                          ForDefinition);
     }
   }
 

lib/IRGen/GenProto.cpp

@@ -2187,8 +2187,19 @@ void IRGenModule::emitSILWitnessTable(SILWitnessTable *wt) {
 
   // Trigger the lazy emission of the foreign type metadata.
   CanType conformingType = conf->getType()->getCanonicalType();
-  if (requiresForeignTypeMetadata(conformingType))
-    (void)getAddrOfForeignTypeMetadataCandidate(conformingType);
+  if (requiresForeignTypeMetadata(conformingType)) {
+    // Make sure we emit the metadata access function.
+    (void)getTypeMetadataAccessFunction(*this, conformingType,
+                                        ForDefinition);
+
+    // Make sure we emit the nominal type descriptor.
+    auto *nominal = conformingType->getAnyNominal();
+    auto entity = LinkEntity::forNominalTypeDescriptor(nominal);
+    if (auto entry = GlobalVars[entity])
+      return;
+
+    emitLazyTypeContextDescriptor(*this, nominal, RequireMetadata);
+  }
 }
 
 /// True if a function's signature in LLVM carries polymorphic parameters.

lib/IRGen/MetadataLayout.cpp

@@ -111,7 +111,7 @@ MetadataLayout &IRGenModule::getMetadataLayout(NominalTypeDecl *decl) {
   auto &entry = MetadataLayouts[decl];
   if (!entry) {
     if (auto theClass = dyn_cast<ClassDecl>(decl)) {
-      if (theClass->isForeign())
+      if (theClass->getForeignClassKind() == ClassDecl::ForeignKind::CFType)
         entry = new ForeignClassMetadataLayout(*this, theClass);
       else
         entry = new ClassMetadataLayout(*this, theClass);
@@ -456,7 +456,7 @@ ClassMetadataLayout::getFieldOffsetVectorOffset(IRGenFunction &IGF) const {
 
 Size irgen::getClassFieldOffsetOffset(IRGenModule &IGM, ClassDecl *theClass,
                                       VarDecl *field) {
-  if (theClass->isForeign())
+  if (theClass->getForeignClassKind() == ClassDecl::ForeignKind::CFType)
     return Size();
 
   return IGM.getClassMetadataLayout(theClass).getStaticFieldOffset(field);
@@ -602,7 +602,8 @@ StructMetadataLayout::getFieldOffsetVectorOffset() const {
 ForeignClassMetadataLayout::ForeignClassMetadataLayout(IRGenModule &IGM,
                                                        ClassDecl *theClass)
     : MetadataLayout(Kind::ForeignClass), Class(theClass) {
-  assert(theClass->isForeign() && "Not a foreign class");
+  assert(theClass->getForeignClassKind() == ClassDecl::ForeignKind::CFType &&
+         "Not a foreign class");
 
   struct Scanner : LayoutScanner<Scanner, ForeignClassMetadataScanner> {
     using super = LayoutScanner;

test/IRGen/objc_runtime_visible_conformance.swift

@@ -0,0 +1,18 @@
+// REQUIRES: objc_interop
+
+// RUN: %target-swift-frontend -I %S/../Inputs/custom-modules %s -emit-ir | %FileCheck %s
+
+import ObjCRuntimeVisible
+
+protocol MyProtocol {}
+protocol YourProtocol {}
+
+extension A : MyProtocol {}
+extension A : YourProtocol {}
+
+// CHECK-LABEL: @"$SSo1ACMn" = linkonce_odr hidden constant <{ {{.*}} }>, section "__TEXT,__const"
+
+// CHECK-LABEL: define linkonce_odr hidden swiftcc %swift.metadata_response @"$SSo1ACMa"({{i32|i64}}) {{.*}} {
+// CHECK: call %objc_class* @objc_lookUpClass
+// CHECK: call %swift.type* @swift_getObjCClassMetadata
+// CHECK: ret