Implicitly import _Concurrency under -enable-experimental-concurrency

Author: rjmccall

include/swift/Frontend/Frontend.h

@@ -337,6 +337,10 @@ class CompilerInvocation {
   /// Whether the Swift -Onone support library should be implicitly imported.
   bool shouldImportSwiftONoneSupport() const;
 
+  /// Whether the Swift Concurrency support library should be implicitly
+  /// imported.
+  bool shouldImportSwiftConcurrency() const;
+
   /// Performs input setup common to these tools:
   /// sil-opt, sil-func-extractor, sil-llvm-gen, and sil-nm.
   /// Return value includes the buffer so caller can keep it alive.

include/swift/Strings.h

@@ -22,6 +22,8 @@ namespace swift {
 constexpr static const StringLiteral STDLIB_NAME = "Swift";
 /// The name of the Onone support library, which is a reserved module name.
 constexpr static const StringLiteral SWIFT_ONONE_SUPPORT = "SwiftOnoneSupport";
+/// The name of the Concurrency module, which supports that extension.
+constexpr static const StringLiteral SWIFT_CONCURRENCY_NAME = "_Concurrency";
 /// The name of the SwiftShims module, which contains private stdlib decls.
 constexpr static const StringLiteral SWIFT_SHIMS_NAME = "SwiftShims";
 /// The name of the Builtin module, which contains Builtin functions.

lib/Frontend/Frontend.cpp

@@ -707,6 +707,10 @@ CompilerInstance::openModuleDoc(const InputFile &input) {
   return None;
 }
 
+bool CompilerInvocation::shouldImportSwiftConcurrency() const {
+  return getLangOptions().EnableExperimentalConcurrency;
+}
+
 /// Implicitly import the SwiftOnoneSupport module in non-optimized
 /// builds. This allows for use of popular specialized functions
 /// from the standard library, which makes the non-optimized builds
@@ -758,6 +762,10 @@ ImplicitImportInfo CompilerInstance::getImplicitImportInfo() const {
     pushImport(SWIFT_ONONE_SUPPORT);
   }
 
+  if (Invocation.shouldImportSwiftConcurrency()) {
+    pushImport(SWIFT_CONCURRENCY_NAME);
+  }
+
   imports.ShouldImportUnderlyingModule = frontendOpts.ImportUnderlyingModule;
   imports.BridgingHeaderPath = frontendOpts.ImplicitObjCHeaderPath;
   return imports;

test/Casting/Casts.swift

@@ -24,6 +24,7 @@
 // RUN: %target-run %t/a.swift5.O.out
 //
 // REQUIRES: executable_test
+// REQUIRES: concurrency
 // UNSUPPORTED: use_os_stdlib
 
 import StdlibUnittest

test/ClangImporter/objc_async.swift

@@ -1,6 +1,7 @@
 // RUN: %target-swift-frontend(mock-sdk: %clang-importer-sdk) -typecheck -I %S/Inputs/custom-modules -enable-experimental-concurrency %s -verify
 
 // REQUIRES: objc_interop
+// REQUIRES: concurrency
 import Foundation
 import ObjCConcurrency
 

test/Concurrency/actor_isolation.swift

@@ -1,8 +1,6 @@
 // RUN: %target-typecheck-verify-swift -enable-experimental-concurrency
 // REQUIRES: concurrency
 
-import _Concurrency
-
 let immutableGlobal: String = "hello"
 var mutableGlobal: String = "can't touch this" // expected-note 2{{var declared here}}
 

test/Concurrency/global_actor_inference.swift

@@ -1,8 +1,6 @@
 // RUN: %target-typecheck-verify-swift -enable-experimental-concurrency
 // REQUIRES: concurrency
 
-import _Concurrency
-
 actor class SomeActor { }
 
 @globalActor

test/Constraints/async.swift

@@ -1,5 +1,7 @@
 // RUN: %target-typecheck-verify-swift -enable-experimental-concurrency
 
+// REQUIRES: concurrency
+
 func doAsynchronously() async { }
 func doSynchronously() { }
 

test/IDE/print_clang_objc_async.swift

@@ -4,6 +4,7 @@
 // RUN: %FileCheck -input-file %t/ObjCConcurrency.printed.txt %s
 
 // REQUIRES: objc_interop
+// REQUIRES: concurrency
 
 // CHECK-LABEL: class SlowServer : NSObject {
 // CHECK-DAG:     func doSomethingSlow(_ operation: String, completionHandler handler: @escaping (Int) -> Void)

test/IRGen/async.swift

@@ -1,5 +1,7 @@
 // RUN: %target-swift-frontend -primary-file %s -emit-ir -enable-experimental-concurrency | %FileCheck %s
 
+// REQUIRES: concurrency
+
 // CHECK: "$s5async1fyyYF"
 public func f() async { }