Add a feature and module interface printing support for Builtin.Job

Author: DougGregor

include/swift/Basic/Features.def

@@ -41,5 +41,6 @@ LANGUAGE_FEATURE(Actors, 0, "actors", langOpts.EnableExperimentalConcurrency)
 LANGUAGE_FEATURE(ConcurrentFunctions, 0, "@concurrent functions", true)
 LANGUAGE_FEATURE(RethrowsProtocol, 0, "@rethrows protocol", true)
 LANGUAGE_FEATURE(GlobalActors, 0, "Global actors", langOpts.EnableExperimentalConcurrency)
+LANGUAGE_FEATURE(BuiltinJob, 0, "Builtin.Job type", true)
 
 #undef LANGUAGE_FEATURE

lib/AST/ASTPrinter.cpp

@@ -19,6 +19,7 @@
 #include "swift/AST/ASTMangler.h"
 #include "swift/AST/ASTVisitor.h"
 #include "swift/AST/Attr.h"
+#include "swift/AST/Builtins.h"
 #include "swift/AST/ClangModuleLoader.h"
 #include "swift/AST/Comment.h"
 #include "swift/AST/Decl.h"
@@ -2577,6 +2578,34 @@ static bool usesFeatureGlobalActors(Decl *decl) {
   return false;
 }
 
+static bool usesFeatureBuiltinJob(Decl *decl) {
+  auto typeHasBuiltinJob = [](Type type) {
+    return type.findIf([&](Type type) {
+      if (auto builtinTy = type->getAs<BuiltinType>())
+        return builtinTy->getBuiltinTypeKind() == BuiltinTypeKind::BuiltinJob;
+
+      return false;
+    });
+  };
+
+  if (auto value = dyn_cast<ValueDecl>(decl)) {
+    if (Type type = value->getInterfaceType()) {
+      if (typeHasBuiltinJob(type))
+        return true;
+    }
+  }
+
+  if (auto patternBinding = dyn_cast<PatternBindingDecl>(decl)) {
+    for (unsigned idx : range(patternBinding->getNumPatternEntries())) {
+      if (Type type = patternBinding->getPattern(idx)->getType())
+        if (typeHasBuiltinJob(type))
+          return true;
+    }
+  }
+
+  return false;
+}
+
 /// Determine the set of "new" features used on a given declaration.
 ///
 /// Note: right now, all features we check for are "new". At some point, we'll