[BitwiseCopyable] Don't infer for @sensitive.

Author: nate-chandler

include/swift/AST/DiagnosticsSema.def

@@ -7728,6 +7728,8 @@ NOTE(note_non_bitwise_copyable_type_indirect_enum_element,none,
      "indirect case is here", ())
 ERROR(non_bitwise_copyable_type_suppressed,none,
       "cannot both conform to and suppress conformance to 'BitwiseCopyable'", ())
+ERROR(non_bitwise_copyable_type_sensitive,none,
+      "a @sensitive type cannot conform to 'BitwiseCopyable'", ())
 ERROR(non_bitwise_copyable_type_cxx_nontrivial,none,
       "non-trivial C++ type cannot conform to 'BitwiseCopyable'", ())
 ERROR(non_bitwise_copyable_c_type_nontrivial,none,

lib/Sema/TypeCheckBitwise.cpp

@@ -237,6 +237,14 @@ static bool checkBitwiseCopyableInstanceStorage(NominalTypeDecl *nominal,
     return true;
   }
 
+  auto &attrs = nominal->getAttrs();
+  if (attrs.hasAttribute<SensitiveAttr>()) {
+    if (!isImplicit(check)) {
+      conformanceDecl->diagnose(diag::non_bitwise_copyable_type_sensitive);
+    }
+    return true;
+  }
+
   if (dc->mapTypeIntoContext(nominal->getDeclaredInterfaceType())
           ->isNoncopyable()) {
     // Already separately diagnosed when explicit.

test/SILGen/bitwise_copyable.swift

@@ -2,6 +2,7 @@
 // RUN:     %s                                                  \
 // RUN:     -emit-silgen                                        \
 // RUN:     -disable-availability-checking                      \
+// RUN:     -enable-experimental-feature Sensitive              \
 // RUN:     -enable-builtin-module
 
 // REQUIRES: asserts
@@ -60,3 +61,10 @@ extension NeverGoingToBeBitwiseCopyable : _BitwiseCopyable {
 }
 
 struct AlsoNotBitwiseCopyable : ~_BitwiseCopyable {}
+
+@sensitive
+struct S_Explicit_Sensitive {
+}
+
+func takeS_Explicit_Sensitive(_ s: S_Explicit_Sensitive) {
+}

test/Sema/bitwise_copyable.swift

@@ -2,6 +2,7 @@
 // RUN:     -disable-availability-checking                   \
 // RUN:     -enable-experimental-feature NonescapableTypes   \
 // RUN:     -enable-experimental-feature NoncopyableGenerics \
+// RUN:     -enable-experimental-feature Sensitive           \
 // RUN:     -enable-builtin-module                           \
 // RUN:     -debug-diagnostic-names
 
@@ -93,6 +94,19 @@ struct S_Explicit_With_Metatype_Optional_AnyObject : _BitwiseCopyable {
   var ty: Optional<AnyObject>.Type
 }
 
+@sensitive
+struct S_Explicit_Sensitive : _BitwiseCopyable { // expected-error {{a @sensitive type cannot conform to 'BitwiseCopyable'}}
+}
+
+@sensitive
+struct S_Implicit_Sensitive {
+}
+
+func passS_Implicit_Sensitive(_ s: S_Implicit_Sensitive) {
+  take1(s) // expected-error   {{type_does_not_conform_decl_owner}}
+           // expected-note@-94 {{where_requirement_failure_one_subst}}
+}
+
 //==============================================================================
 //===========================DEPENDENCY-FREE TESTS=(END)======================}}
 //==============================================================================