Eliminate the EnableExperimentalDistributed language option.

Nothing is using it because this feature is enabled by default.

Author: DougGregor

include/swift/Basic/LangOptions.h

@@ -343,9 +343,6 @@ namespace swift {
     /// Enable inference of Sendable conformances for public types.
     bool EnableInferPublicSendable = false;
 
-    /// Enable experimental 'distributed' actors and functions.
-    bool EnableExperimentalDistributed = true;
-
     /// Enable experimental 'move only' features.
     bool EnableExperimentalMoveOnly = false;
 

lib/Frontend/CompilerInvocation.cpp

@@ -459,9 +459,6 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
   Opts.EnableExperimentalVariadicGenerics |=
     Args.hasArg(OPT_enable_experimental_variadic_generics);
 
-  Opts.EnableExperimentalDistributed |=
-    Args.hasArg(OPT_enable_experimental_distributed);
-
   Opts.EnableExperimentalMoveOnly |=
     Args.hasArg(OPT_enable_experimental_move_only);
 
@@ -485,12 +482,6 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
   Opts.DisableImplicitConcurrencyModuleImport |=
     Args.hasArg(OPT_disable_implicit_concurrency_module_import);
 
-  /// experimental distributed also implicitly enables experimental concurrency
-  Opts.EnableExperimentalDistributed |=
-    Args.hasArg(OPT_enable_experimental_distributed);
-  Opts.EnableExperimentalConcurrency |=
-    Args.hasArg(OPT_enable_experimental_distributed);
-
   if (Args.hasArg(OPT_enable_experimental_async_top_level))
     Diags.diagnose(SourceLoc(), diag::warn_flag_deprecated,
                    "-enable-experimental-async-top-level");

tools/sil-opt/SILOpt.cpp

@@ -559,8 +559,6 @@ int main(int argc, char **argv) {
   }
   Invocation.getLangOptions().EnableExperimentalConcurrency =
     EnableExperimentalConcurrency;
-  Invocation.getLangOptions().EnableExperimentalDistributed =
-    EnableExperimentalDistributed;
   Optional<bool> enableExperimentalMoveOnly =
       toOptionalBool(EnableExperimentalMoveOnly);
   if (enableExperimentalMoveOnly)

tools/swift-ide-test/swift-ide-test.cpp

@@ -4271,13 +4271,6 @@ int main(int argc, char *argv[]) {
     InitInvok.getLangOptions().EnableExperimentalNamedOpaqueTypes = true;
   }
 
-  if (options::EnableExperimentalDistributed) {
-    // distributed implies concurrency features:
-    InitInvok.getLangOptions().EnableExperimentalConcurrency = true;
-    // enable 'distributed' parsing and features
-    InitInvok.getLangOptions().EnableExperimentalDistributed = true;
-  }
-
   if (!options::Triple.empty())
     InitInvok.setTargetTriple(options::Triple);
   if (!options::SwiftVersion.empty()) {