AST: teach getOpaqueResultTypeDecl() to get result for serialized AST

TBD was missing several opaque type descriptor symbols. The root causes
are: (1) the AST API called by TBD doesn't return opaque type decl if
the decl is from a serialized AST; and (2) the access level of opaque
type decl isn't serialized so TBD considers them as internal.

This change fixes both.

rdar://61833970

Author: nkcsgexi

include/swift/AST/ASTMangler.h

@@ -238,6 +238,8 @@ class ASTMangler : public Mangler {
 
   std::string mangleOpaqueTypeDecl(const OpaqueTypeDecl *decl);
 
+  std::string mangleOpaqueTypeDecl(const ValueDecl *decl);
+
   enum SpecialContext {
     ObjCContext,
     ClangImporterContext,

lib/AST/ASTMangler.cpp

@@ -693,9 +693,13 @@ std::string ASTMangler::mangleLocalTypeDecl(const TypeDecl *type) {
 }
 
 std::string ASTMangler::mangleOpaqueTypeDecl(const OpaqueTypeDecl *decl) {
+  return mangleOpaqueTypeDecl(decl->getNamingDecl());
+}
+
+std::string ASTMangler::mangleOpaqueTypeDecl(const ValueDecl *decl) {
   DWARFMangling = true;
   OptimizeProtocolNames = false;
-  return mangleDeclAsUSR(decl->getNamingDecl(), MANGLING_PREFIX_STR);
+  return mangleDeclAsUSR(decl, MANGLING_PREFIX_STR);
 }
 
 void ASTMangler::appendSymbolKind(SymbolKind SKind) {

lib/AST/Decl.cpp

@@ -19,6 +19,7 @@
 #include "swift/AST/AccessScope.h"
 #include "swift/AST/ASTContext.h"
 #include "swift/AST/ASTWalker.h"
+#include "swift/AST/ASTMangler.h"
 #include "swift/AST/DiagnosticEngine.h"
 #include "swift/AST/DiagnosticsSema.h"
 #include "swift/AST/ExistentialLayout.h"
@@ -2875,8 +2876,18 @@ OpaqueReturnTypeRepr *ValueDecl::getOpaqueResultTypeRepr() const {
 }
 
 OpaqueTypeDecl *ValueDecl::getOpaqueResultTypeDecl() const {
-  if (getOpaqueResultTypeRepr() == nullptr)
+  if (getOpaqueResultTypeRepr() == nullptr) {
+    if (isa<ModuleDecl>(this))
+      return nullptr;
+    auto file = cast<FileUnit>(getDeclContext()->getModuleScopeContext());
+    // Don't look up when the decl is from source, otherwise a cycle will happen.
+    if (file->getKind() == FileUnitKind::SerializedAST) {
+      Mangle::ASTMangler mangler;
+      auto name = mangler.mangleOpaqueTypeDecl(this);
+      return file->lookupOpaqueResultType(name);
+    }
     return nullptr;
+  }
 
   return evaluateOrDefault(getASTContext().evaluator,
     OpaqueResultTypeRequest{const_cast<ValueDecl *>(this)},

lib/Serialization/Deserialization.cpp

@@ -3230,11 +3230,11 @@ class DeclDeserializer {
     TypeID interfaceTypeID;
     GenericSignatureID genericSigID;
     SubstitutionMapID underlyingTypeID;
-    
+    uint8_t rawAccessLevel;
     decls_block::OpaqueTypeLayout::readRecord(scratch, contextID,
                                               namingDeclID, interfaceSigID,
                                               interfaceTypeID, genericSigID,
-                                              underlyingTypeID);
+                                              underlyingTypeID, rawAccessLevel);
 
     auto declContext = MF.getDeclContext(contextID);
     auto interfaceSig = MF.getGenericSignature(interfaceSigID);
@@ -3254,6 +3254,11 @@ class DeclDeserializer {
     auto namingDecl = cast<ValueDecl>(MF.getDecl(namingDeclID));
     opaqueDecl->setNamingDecl(namingDecl);
 
+    if (auto accessLevel = getActualAccessLevel(rawAccessLevel))
+      opaqueDecl->setAccess(*accessLevel);
+    else
+      MF.fatal();
+
     if (auto genericParams = MF.maybeReadGenericParams(opaqueDecl)) {
       ctx.evaluator.cacheOutput(GenericParamListRequest{opaqueDecl},
                                 std::move(genericParams));

lib/Serialization/ModuleFormat.h

@@ -55,7 +55,7 @@ const uint16_t SWIFTMODULE_VERSION_MAJOR = 0;
 /// describe what change you made. The content of this comment isn't important;
 /// it just ensures a conflict if two people change the module format.
 /// Don't worry about adhering to the 80-column limit for this line.
-const uint16_t SWIFTMODULE_VERSION_MINOR = 553; // change to USR mangling
+const uint16_t SWIFTMODULE_VERSION_MINOR = 554; // serialize accesslevel for OpaqueTypeDecl
 
 /// A standard hash seed used for all string hashes in a serialized module.
 ///
@@ -1292,7 +1292,8 @@ namespace decls_block {
     GenericSignatureIDField, // interface generic signature
     TypeIDField, // interface type for opaque type
     GenericSignatureIDField, // generic environment
-    SubstitutionMapIDField // optional substitution map for underlying type
+    SubstitutionMapIDField, // optional substitution map for underlying type
+    AccessLevelField // access level
     // trailed by generic parameters
   >;
 

lib/Serialization/Serialization.cpp

@@ -3454,12 +3454,13 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
     SubstitutionMapID underlyingTypeID = 0;
     if (auto underlying = opaqueDecl->getUnderlyingTypeSubstitutions())
       underlyingTypeID = S.addSubstitutionMapRef(*underlying);
-
+    uint8_t rawAccessLevel =
+      getRawStableAccessLevel(opaqueDecl->getFormalAccess());
     unsigned abbrCode = S.DeclTypeAbbrCodes[OpaqueTypeLayout::Code];
     OpaqueTypeLayout::emitRecord(S.Out, S.ScratchRecord, abbrCode,
                                  contextID.getOpaqueValue(), namingDeclID,
                                  interfaceSigID, interfaceTypeID, genericSigID,
-                                 underlyingTypeID);
+                                 underlyingTypeID, rawAccessLevel);
     writeGenericParams(opaqueDecl->getGenericParams());
   }
 

test/TBD/emit-tbd-from-driver.swift

@@ -0,0 +1,11 @@
+// REQUIRES: VENDOR=apple
+// RUN: %empty-directory(%t)
+
+// RUN: echo "public func foo() -> some CustomStringConvertible { 32 }" > %t/source1.swift
+// RUN: echo "" > %t/source2.swift
+
+// RUN: %target-build-swift -target x86_64-apple-macosx10.15 -module-name multifile %t/source1.swift  %t/source2.swift -Xfrontend -validate-tbd-against-ir=all -emit-tbd -emit-tbd-path %t/multifile.tbd -enable-library-evolution -emit-module
+
+// RUN: %FileCheck %s < %t/multifile.tbd
+
+// CHECK: s9multifile3fooQryFQOMQ