[Concurrency] More work on the custom executor implementation.

Added an `-executor-factory` argument to the compiler to let you safely
specify the executors you wish to use (by naming a type that returns
them).

Also added some tests of the new functionality.

rdar://141348916

Author: al45tair

include/swift/AST/DiagnosticsSIL.def

@@ -1133,6 +1133,14 @@ NOTE(rbi_add_generic_parameter_sendable_conformance,none,
      "consider making generic parameter %0 conform to the 'Sendable' protocol",
      (Type))
 
+// Concurrency related diagnostics
+ERROR(cannot_find_executor_factory_type, none,
+      "the specified executor factory '%0' could not be found", (StringRef))
+ERROR(executor_factory_must_conform, none,
+      "the executor factory '%0' does not conform to 'ExecutorFactory'", (Type))
+ERROR(executor_factory_not_supported, none,
+      "deployment target too low for executor factory specification", ())
+
 //===----------------------------------------------------------------------===//
 //                           MARK: Misc Diagnostics
 //===----------------------------------------------------------------------===//

include/swift/AST/FeatureAvailability.def

@@ -80,6 +80,7 @@ FEATURE(IsolatedDeinit,                                 (6, 1))
 
 FEATURE(ValueGenericType,                               (6, 2))
 FEATURE(InitRawStructMetadata2,                         (6, 2))
+FEATURE(CustomExecutors,                                (6, 2))
 
 FEATURE(TaskExecutor,                                   FUTURE)
 FEATURE(Differentiation,                                FUTURE)

include/swift/AST/KnownProtocols.def

@@ -97,6 +97,7 @@ PROTOCOL(Executor)
 PROTOCOL(SerialExecutor)
 PROTOCOL(TaskExecutor)
 PROTOCOL(GlobalActor)
+PROTOCOL(ExecutorFactory)
 
 PROTOCOL_(BridgedNSError)
 PROTOCOL_(BridgedStoredNSError)

include/swift/Basic/LangOptions.h

@@ -396,6 +396,10 @@ namespace swift {
     /// Specifies how strict concurrency checking will be.
     StrictConcurrency StrictConcurrencyLevel = StrictConcurrency::Minimal;
 
+    /// Specifies the name of the executor factory to use to create the
+    /// default executors for Swift Concurrency.
+    std::optional<std::string> ExecutorFactory;
+
     /// Enable experimental concurrency model.
     bool EnableExperimentalConcurrency = false;
 

include/swift/Option/Options.td

@@ -985,6 +985,16 @@ def strict_concurrency : Joined<["-"], "strict-concurrency=">,
            "concurrency model, or 'complete' ('Sendable' and other checking is "
            "enabled for all code in the module)">;
 
+def executor_factory : JoinedOrSeparate<["-"], "executor-factory">,
+  Flags<[FrontendOption]>,
+  HelpText<"Specify the factory to use to create the default executors for "
+           "Swift Concurrency.  This must be a type conforming to the "
+           "'ExecutorFactory' protocol.">,
+  MetaVarName<"<factory-type>">;
+def executor_factory_EQ : Joined<["-"], "executor-factory=">,
+  Flags<[FrontendOption]>,
+  Alias<executor_factory>;
+
 def enable_experimental_feature :
   Separate<["-"], "enable-experimental-feature">,
   Flags<[FrontendOption, ModuleInterfaceOption]>,

lib/AST/ASTContext.cpp

@@ -1438,6 +1438,7 @@ ProtocolDecl *ASTContext::getProtocol(KnownProtocolKind kind) const {
   case KnownProtocolKind::Executor:
   case KnownProtocolKind::TaskExecutor:
   case KnownProtocolKind::SerialExecutor:
+  case KnownProtocolKind::ExecutorFactory:
     M = getLoadedModule(Id_Concurrency);
     break;
   case KnownProtocolKind::DistributedActor:

lib/ClangImporter/SortedCFDatabase.def.gyb

@@ -39,7 +39,7 @@ with codecs.open(CFDatabaseFile, encoding='utf-8', errors='strict') as f:
       continue
 
     # Otherwise, check for lines like FOO(BAR)
-    m = re.match('^\w+\((\w+)\)', line)
+    m = re.match(r'^\w+\((\w+)\)', line)
     if m:
       lineForName[m.group(1)] = line
 }%

lib/Driver/ToolChains.cpp

@@ -377,6 +377,10 @@ void ToolChain::addCommonFrontendArgs(const OutputInfo &OI,
     arguments.push_back(inputArgs.MakeArgString(globalRemapping));
   }
 
+  if (inputArgs.hasArg(options::OPT_executor_factory)) {
+    inputArgs.AddLastArg(arguments, options::OPT_executor_factory);
+  }
+
   // Pass through the values passed to -Xfrontend.
   inputArgs.AddAllArgValues(arguments, options::OPT_Xfrontend);
 

lib/Frontend/CompilerInvocation.cpp

@@ -1314,6 +1314,12 @@ static bool ParseLangArgs(LangOptions &Opts, ArgList &Args,
     Opts.enableFeature(Feature::RegionBasedIsolation);
   }
 
+  // Get the executor factory name
+  if (const Arg *A = Args.getLastArg(OPT_executor_factory)) {
+    printf("Got executor-factory option\n");
+    Opts.ExecutorFactory = A->getValue();
+  }
+
   Opts.WarnImplicitOverrides =
     Args.hasArg(OPT_warn_implicit_overrides);
 

lib/IRGen/GenMeta.cpp

@@ -7045,6 +7045,7 @@ SpecialProtocol irgen::getSpecialProtocolID(ProtocolDecl *P) {
   case KnownProtocolKind::Executor:
   case KnownProtocolKind::SerialExecutor:
   case KnownProtocolKind::TaskExecutor:
+  case KnownProtocolKind::ExecutorFactory:
   case KnownProtocolKind::Sendable:
   case KnownProtocolKind::UnsafeSendable:
   case KnownProtocolKind::RangeReplaceableCollection: