AST: add feature flag "FixedArrays"

Author: eeckstein

include/swift/Basic/Features.def

@@ -273,6 +273,9 @@ EXPERIMENTAL_FEATURE(ExtractConstantsFromMembers, false)
 /// Enable bitwise-copyable feature.
 EXPERIMENTAL_FEATURE(BitwiseCopyable, true)
 
+/// Enables the FixedArray data type.
+EXPERIMENTAL_FEATURE(FixedArrays, false)
+
 #undef EXPERIMENTAL_FEATURE_EXCLUDED_FROM_MODULE_INTERFACE
 #undef EXPERIMENTAL_FEATURE
 #undef UPCOMING_FEATURE

lib/AST/ASTPrinter.cpp

@@ -3616,6 +3616,10 @@ static bool usesFeatureNonEscapableTypes(Decl *decl) {
   return false;
 }
 
+static bool usesFeatureFixedArrays(Decl *decl) {
+  return false;
+}
+
 static bool hasParameterPacks(Decl *decl) {
   if (auto genericContext = decl->getAsGenericContext()) {
     auto sig = genericContext->getGenericSignature();