Merge pull request #64991 from xymus/serial-opaque-types

[Serialization] Only read the underlying type of an opaque type if inlinable

Author: xymus

lib/Serialization/Deserialization.cpp

@@ -3888,7 +3888,17 @@ class DeclDeserializer {
       opaqueDecl->setGenericSignature(genericSig);
     else
       opaqueDecl->setGenericSignature(GenericSignature());
-    if (underlyingTypeSubsID) {
+
+    auto *AFD = dyn_cast<AbstractFunctionDecl>(namingDecl);
+    if (MF.getResilienceStrategy() == ResilienceStrategy::Resilient &&
+        !MF.FileContext->getParentModule()->isMainModule() &&
+        AFD && AFD->getResilienceExpansion() != ResilienceExpansion::Minimal) {
+      // Do not try to read the underlying type information if the function
+      // is not inlinable in clients. This reflects the swiftinterface behavior
+      // in where clients are only aware of the underlying type when the body
+      // of the function is public.
+
+    } else if (underlyingTypeSubsID) {
       auto subMapOrError = MF.getSubstitutionMapChecked(underlyingTypeSubsID);
       if (!subMapOrError) {
         // If the underlying type references internal details, ignore it.

test/Serialization/Safety/skip-reading-internal-details.swift

@@ -86,6 +86,30 @@ public struct PublicStruct {
     }
 }
 
+// resultBuilder scenario
+public protocol V {}
+
+@resultBuilder
+public struct VB {
+    public static func buildExpression<Content>(_ content: Content) -> Content where Content : V { fatalError() }
+    public static func buildBlock() -> V { fatalError() }
+    public static func buildBlock<Content>(_ content: Content) -> Content where Content : V { fatalError() }
+}
+
+public struct EV : V {
+    public init () {}
+}
+
+@available(SwiftStdlib 5.1, *)
+public extension V {
+  @VB
+  func opaqueReferencingPrivate() -> some V {
+    referencedPrivateFunc(v: EV())
+  }
+
+  private func referencedPrivateFunc(v: some V) -> some V { return v }
+}
+
 //--- Client.swift
 
 import Lib
@@ -94,3 +118,8 @@ var x = PublicStruct()
 
 // Trigger a typo correction that reads all members.
 x.notAMember() // expected-error {{value of type 'PublicStruct' has no member 'notAMember'}}
+
+if #available(SwiftStdlib 5.1, *) {
+  let v = EV()
+  let _ = v.opaqueReferencingPrivate()
+}