Sema: Allow nested structs in embedded code

Author: xymus

lib/Sema/TypeCheckDeclPrimary.cpp

@@ -2946,7 +2946,8 @@ class DeclChecker : public DeclVisitor<DeclChecker> {
 
     // We don't allow nested types inside inlinable contexts.
     auto kind = DC->getFragileFunctionKind();
-    if (kind.kind != FragileFunctionKind::None) {
+    if (kind.kind != FragileFunctionKind::None &&
+        kind.kind != FragileFunctionKind::EmbeddedAlwaysEmitIntoClient) {
       NTD->diagnose(diag::local_type_in_inlinable_function, NTD->getName(),
                     kind.getSelector());
     }

test/Sema/implementation-only-import-embedded.swift

@@ -148,6 +148,8 @@ internal func explicitNonInliableInternal(arg: StructFromDirect = StructFromDire
   implicitlyInlinablePublic()
   implicitlyInlinablePrivate()
   explicitNonInliable()
+
+  struct NestedStruct {}
 }
 
 struct Accessors {