[5.9] AST: Inherit access level of an opaque type decl from its naming decl

lib/AST/Decl.cpp

@@ -3868,6 +3868,12 @@ getAdjustedFormalAccess(const ValueDecl *VD, const DeclContext *useDC,
 }
 
 AccessLevel ValueDecl::getEffectiveAccess() const {
+  // Opaque type decls inherit accessibility from their naming decl.
+  if (auto *opaqueType = dyn_cast<OpaqueTypeDecl>(this)) {
+    if (auto *namingDecl = opaqueType->getNamingDecl())
+      return namingDecl->getEffectiveAccess();
+  }
+
   auto effectiveAccess =
     getAdjustedFormalAccess(this, /*useDC=*/nullptr,
                             /*treatUsableFromInlineAsPublic=*/true);

test/IRGen/Inputs/AlwaysInlineIntoWithOpaque.swift

@@ -14,3 +14,16 @@ public func testInlineWithOpaque() -> some P {
   }
   return 2.0
 }
+
+@_alwaysEmitIntoClient
+public func testInlineWithOpaqueUsableFromInline() -> some P {
+  if #available(macOS 9.0, *) {
+    return usableFromInline()
+  }
+  return 4.0
+}
+
+@usableFromInline
+func usableFromInline() -> some P {
+  return 3
+}

test/IRGen/Inputs/AlwaysInlineIntoWithOpaqueReplacement.swift

@@ -6,3 +6,8 @@ extension Int : P {
 
 extension Double : P {
 }
+
+@usableFromInline
+func usableFromInline() -> some P {
+  return 3
+}

test/IRGen/opaque_result_alwaysInlineIntoClient.swift

@@ -1,11 +1,11 @@
 // RUN: %empty-directory(%t)
-// RUN: %target-build-swift -target %target-cpu-apple-macosx10.15 -parse-as-library -emit-library -emit-module-path %t/AlwaysInlineIntoWithOpaque.swiftmodule -module-name AlwaysInlineIntoWithOpaque %S/Inputs/AlwaysInlineIntoWithOpaque.swift -o %t/%target-library-name(AlwaysInlineIntoWithOpaque)
+// RUN: %target-build-swift -target %target-cpu-apple-macosx10.15 -parse-as-library -emit-library -emit-module-path %t/AlwaysInlineIntoWithOpaque.swiftmodule -module-name AlwaysInlineIntoWithOpaque -enable-library-evolution %S/Inputs/AlwaysInlineIntoWithOpaque.swift -o %t/%target-library-name(AlwaysInlineIntoWithOpaque)
 // RUN: %target-codesign %t/%target-library-name(AlwaysInlineIntoWithOpaque)
 // RUN: %target-build-swift -target %target-cpu-apple-macosx10.15 -lAlwaysInlineIntoWithOpaque -module-name main -I %t -L %t %s -o %t/a.out
 // RUN: %target-codesign %t/a.out
 // RUN: %target-run %t/a.out | %FileCheck %s
 
-// RUN: %target-build-swift -target %target-cpu-apple-macosx10.15 -parse-as-library -emit-library -emit-module-path %t/AlwaysInlineIntoWithOpaque.swiftmodule -module-name AlwaysInlineIntoWithOpaque %S/Inputs/AlwaysInlineIntoWithOpaqueReplacement.swift -o %t/%target-library-name(AlwaysInlineIntoWithOpaque)
+// RUN: %target-build-swift -target %target-cpu-apple-macosx10.15 -parse-as-library -emit-library -emit-module-path %t/AlwaysInlineIntoWithOpaque.swiftmodule -module-name AlwaysInlineIntoWithOpaque  -enable-library-evolution %S/Inputs/AlwaysInlineIntoWithOpaqueReplacement.swift -o %t/%target-library-name(AlwaysInlineIntoWithOpaque)
 // RUN: %target-codesign %t/a.out
 // RUN: %target-run %t/a.out | %FileCheck %s
 
@@ -27,3 +27,11 @@ public func test() {
 
 test()
 // CHECK: 1
+
+public func testUsableFromInline() {
+  let p = testInlineWithOpaqueUsableFromInline()
+  print(p)
+}
+
+testUsableFromInline()
+// CHECK: 3

test/TBD/opaque_result_type.swift

@@ -77,6 +77,11 @@ public func dynReplacement(x: String) -> some P {
   return "replaced"
 }
 
+@usableFromInline
+func ufi() -> some O {
+  return 1
+}
+
 extension String: P {
   public func poo() -> some O {
     return 0