Serialize opaque return type of var/subscript decls.

Author: jckarter

include/swift/Serialization/ModuleFormat.h

@@ -1039,6 +1039,7 @@ namespace decls_block {
     DeclIDField,  // overridden decl
     AccessLevelField, // access level
     AccessLevelField, // setter access, if applicable
+    DeclIDField, // opaque return type decl
     BCArray<TypeIDField> // accessors and dependencies
   >;
 
@@ -1198,6 +1199,7 @@ namespace decls_block {
     AccessLevelField, // setter access, if applicable
     StaticSpellingKindField,    // is subscript static?
     BCVBR<5>,    // number of parameter name components
+    DeclIDField, // opaque return type decl
     BCArray<IdentifierIDField> // name components,
                                // followed by DeclID accessors,
                                // followed by TypeID dependencies

lib/Serialization/Deserialization.cpp

@@ -2620,7 +2620,7 @@ class swift::DeclDeserializer {
     uint8_t rawAccessLevel, rawSetterAccessLevel;
     TypeID interfaceTypeID;
     ModuleFile::AccessorRecord accessors;
-    DeclID overriddenID;
+    DeclID overriddenID, opaqueReturnTypeID;
     ArrayRef<uint64_t> accessorAndDependencyIDs;
 
     decls_block::VarLayout::readRecord(scratch, nameID, contextID,
@@ -2633,6 +2633,7 @@ class swift::DeclDeserializer {
                                        interfaceTypeID,
                                        overriddenID,
                                        rawAccessLevel, rawSetterAccessLevel,
+                                       opaqueReturnTypeID,
                                        accessorAndDependencyIDs);
 
     Identifier name = MF.getIdentifier(nameID);
@@ -2733,6 +2734,11 @@ class swift::DeclDeserializer {
     if (var->hasStorage())
       AddAttribute(new (ctx) HasStorageAttr(/*isImplicit:*/true));
 
+    if (opaqueReturnTypeID) {
+      var->setOpaqueResultTypeDecl(
+                         cast<OpaqueTypeDecl>(MF.getDecl(opaqueReturnTypeID)));
+    }
+    
     return var;
   }
 
@@ -3543,7 +3549,7 @@ class swift::DeclDeserializer {
     GenericEnvironmentID genericEnvID;
     TypeID elemInterfaceTypeID;
     ModuleFile::AccessorRecord accessors;
-    DeclID overriddenID;
+    DeclID overriddenID, opaqueReturnTypeID;
     uint8_t rawAccessLevel, rawSetterAccessLevel, rawStaticSpelling;
     uint8_t opaqueReadOwnership, readImpl, writeImpl, readWriteImpl;
     unsigned numArgNames, numAccessors;
@@ -3560,6 +3566,7 @@ class swift::DeclDeserializer {
                                              overriddenID, rawAccessLevel,
                                              rawSetterAccessLevel,
                                              rawStaticSpelling, numArgNames,
+                                             opaqueReturnTypeID,
                                              argNameAndDependencyIDs);
     // Resolve the name ids.
     SmallVector<Identifier, 2> argNames;
@@ -3644,6 +3651,12 @@ class swift::DeclDeserializer {
     subscript->setOverriddenDecl(cast_or_null<SubscriptDecl>(overridden.get()));
     if (subscript->getOverriddenDecl())
       AddAttribute(new (ctx) OverrideAttr(SourceLoc()));
+    
+    if (opaqueReturnTypeID) {
+      subscript->setOpaqueResultTypeDecl(
+                         cast<OpaqueTypeDecl>(MF.getDecl(opaqueReturnTypeID)));
+    }
+    
     return subscript;
   }
 

lib/Serialization/Serialization.cpp

@@ -3284,6 +3284,7 @@ void Serializer::writeDecl(const Decl *D) {
                           addTypeRef(ty),
                           addDeclRef(var->getOverriddenDecl()),
                           rawAccessLevel, rawSetterAccessLevel,
+                          addDeclRef(var->getOpaqueResultTypeDecl()),
                           accessorsAndDependencies);
     break;
   }
@@ -3548,6 +3549,7 @@ void Serializer::writeDecl(const Decl *D) {
                                 rawStaticSpelling,
                                 subscript->
                                   getFullName().getArgumentNames().size(),
+                                addDeclRef(subscript->getOpaqueResultTypeDecl()),
                                 nameComponentsAndDependencies);
 
     writeGenericParams(subscript->getGenericParams());

test/Serialization/Inputs/OpaqueCrossFileB.swift

@@ -7,3 +7,15 @@ public struct FooImpl: Foo {
 public func anyFoo() -> some Foo {
   return FooImpl()
 }
+
+public var anyFooProp: some Foo {
+  return FooImpl()
+}
+
+public struct Subscript {
+  public init() {}
+
+  public subscript() -> some Foo {
+    return FooImpl()
+  }
+}

test/Serialization/opaque_cross_file.swift

@@ -5,4 +5,6 @@
 import OpaqueCrossFileB
 
 dump(anyFoo())
+dump(anyFooProp)
+dump(Subscript()[])