Adopt experimental feature approach for flow-sensitive concurrency captures

Author: DougGregor

include/swift/Basic/Features.def

@@ -86,6 +86,7 @@ SUPPRESSIBLE_LANGUAGE_FEATURE(NoAsyncAvailability, 340, "@available(*, noasync)"
 EXPERIMENTAL_FEATURE(StaticAssert)
 EXPERIMENTAL_FEATURE(VariadicGenerics)
 EXPERIMENTAL_FEATURE(NamedOpaqueTypes)
+EXPERIMENTAL_FEATURE(FlowSensitiveConcurrencyCaptures)
 
 #undef EXPERIMENTAL_FEATURE
 #undef SUPPRESSIBLE_LANGUAGE_FEATURE

include/swift/Basic/LangOptions.h

@@ -321,9 +321,6 @@ namespace swift {
     /// in calls to generic functions.
     bool EnableOpenedExistentialTypes = false;
 
-    /// Enable experimental flow-sensitive concurrent captures.
-    bool EnableExperimentalFlowSensitiveConcurrentCaptures = false;
-
     /// Disable experimental ClangImporter diagnostics.
     bool DisableExperimentalClangImporterDiagnostics = false;
 

lib/AST/ASTPrinter.cpp

@@ -3007,6 +3007,10 @@ static bool usesFeatureNamedOpaqueTypes(Decl *decl) {
   return false;
 }
 
+static bool usesFeatureFlowSensitiveConcurrencyCaptures(Decl *decl) {
+  return false;
+}
+
 static void
 suppressingFeatureNoAsyncAvailability(PrintOptions &options,
                                       llvm::function_ref<void()> action) {

lib/Frontend/CompilerInvocation.cpp

@@ -465,8 +465,6 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
     Args.hasFlag(OPT_enable_infer_public_concurrent_value,
                  OPT_disable_infer_public_concurrent_value,
                  false);
-  Opts.EnableExperimentalFlowSensitiveConcurrentCaptures |=
-    Args.hasArg(OPT_enable_experimental_flow_sensitive_concurrent_captures);
 
   Opts.DisableExperimentalClangImporterDiagnostics |=
       Args.hasArg(OPT_disable_experimental_clang_importer_diagnostics);
@@ -662,6 +660,8 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
     Opts.Features.insert(Feature::StaticAssert);
   if (Args.hasArg(OPT_enable_experimental_associated_type_inference))
     Opts.Features.insert(Feature::NamedOpaqueTypes);
+  if (Args.hasArg(OPT_enable_experimental_flow_sensitive_concurrent_captures))
+    Opts.Features.insert(Feature::FlowSensitiveConcurrencyCaptures);
 
   Opts.EnableAppExtensionRestrictions |= Args.hasArg(OPT_enable_app_extension);
 

lib/Sema/TypeCheckConcurrency.cpp

@@ -2634,7 +2634,8 @@ namespace {
         // allow reads, depending on a SIL diagnostic pass to identify the
         // remaining race conditions.
         if (!var->supportsMutation() ||
-            (ctx.LangOpts.EnableExperimentalFlowSensitiveConcurrentCaptures &&
+            (ctx.LangOpts.hasFeature(
+                 Feature::FlowSensitiveConcurrencyCaptures) &&
              parent.dyn_cast<LoadExpr *>())) {
           return false;
         }