[Serialization] Disable deserialization safety along with access control

Disabling access control is fundamentally incompatible with
deserialization safety. Let's turn off safety automatically when in use.

This was reported by a few tests:

stdlib/Dictionary.swift
stdlib/Set.swift
stdlib/SetOperations.swift.gyb
stdlib/SwiftNativeNSBase.swift

Author: xymus

lib/Frontend/CompilerInvocation.cpp

@@ -563,6 +563,17 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
                                OPT_disable_deserialization_safety)) {
     Opts.EnableDeserializationSafety
       = A->getOption().matches(OPT_enable_deserialization_safety);
+  } else if (auto A = Args.getLastArg(OPT_enable_access_control,
+                                      OPT_disable_access_control)) {
+    // Disable deserialization safety along with access control.
+    Opts.EnableDeserializationSafety
+      = A->getOption().matches(OPT_enable_access_control);
+  }
+
+  if (auto A = Args.getLastArg(OPT_enable_access_control,
+                               OPT_disable_access_control)) {
+    Opts.EnableAccessControl
+      = A->getOption().matches(OPT_enable_access_control);
   }
 
   // Whether '/.../' regex literals are enabled. This implies experimental
@@ -616,12 +627,6 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
       Args.hasArg(OPT_warn_on_potentially_unavailable_enum_case);
   Opts.WarnOnEditorPlaceholder |= Args.hasArg(OPT_warn_on_editor_placeholder);
 
-  if (auto A = Args.getLastArg(OPT_enable_access_control,
-                               OPT_disable_access_control)) {
-    Opts.EnableAccessControl
-      = A->getOption().matches(OPT_enable_access_control);
-  }
-
   if (auto A = Args.getLastArg(OPT_disable_typo_correction,
                                OPT_typo_correction_limit)) {
     if (A->getOption().matches(OPT_disable_typo_correction))

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

@@ -18,6 +18,11 @@
 // RUN:   -disable-deserialization-safety 2>&1 \
 // RUN:   | %FileCheck --check-prefixes=NEEDED,UNSAFE %s
 
+// RUN: %target-swift-frontend -typecheck %t/Client.swift -I %t \
+// RUN:   -verify -Xllvm -debug-only=Serialization \
+// RUN:   -disable-access-control 2>&1 \
+// RUN:   | %FileCheck --check-prefixes=NEEDED,UNSAFE %s
+
 // RUN: %target-swift-frontend -typecheck %t/Client.swift -I %t \
 // RUN:   -verify -Xllvm -debug-only=Serialization \
 // RUN:   -enable-deserialization-safety 2>&1 \