Don't diagnose accesses to global/static variables within the same module

lib/Sema/TypeCheckConcurrency.cpp

@@ -3094,6 +3094,14 @@ namespace {
         return false;
       }
 
+      // If global variable checking is enabled and the global variable is
+      // from the same module as the reference, we'll already have diagnosed
+      // the global variable itself.
+      if (ctx.LangOpts.hasFeature(Feature::GlobalConcurrency) &&
+          var->getDeclContext()->getParentModule() ==
+              getDeclContext()->getParentModule())
+        return false;
+
       const auto import = var->findImport(getDeclContext());
       const bool isPreconcurrencyImport =
           import && import->options.contains(ImportFlags::Preconcurrency);

test/Concurrency/Inputs/GlobalVariables.swift

@@ -9,3 +9,6 @@ public struct Globals {
 
   public init() {}
 }
+
+public var mutableGlobal: String = "can't touch this"
+public var globalInt = 17

test/Concurrency/actor_isolation.swift

@@ -1,23 +1,19 @@
 // RUN: %empty-directory(%t)
 
 // RUN: %target-swift-frontend -emit-module -emit-module-path %t/OtherActors.swiftmodule -module-name OtherActors %S/Inputs/OtherActors.swift -disable-availability-checking
+// RUN: %target-swift-frontend -emit-module -emit-module-path %t/GlobalVariables.swiftmodule -module-name GlobalVariables %S/Inputs/GlobalVariables.swift -disable-availability-checking -parse-as-library
 
 // RUN: %target-swift-frontend -I %t  -disable-availability-checking -strict-concurrency=complete -parse-as-library -emit-sil -o /dev/null -verify -enable-upcoming-feature GlobalActorIsolatedTypesUsability %s
 // RUN: %target-swift-frontend -I %t  -disable-availability-checking -strict-concurrency=complete -parse-as-library -emit-sil -o /dev/null -verify -enable-upcoming-feature RegionBasedIsolation -enable-upcoming-feature GlobalActorIsolatedTypesUsability %s
 
 // REQUIRES: concurrency
 // REQUIRES: asserts
 
+import GlobalVariables
 import OtherActors // expected-warning{{add '@preconcurrency' to suppress 'Sendable'-related warnings from module 'OtherActors'}}{{1-1=@preconcurrency }}
 
 let immutableGlobal: String = "hello"
 
-// expected-warning@+4 {{var 'mutableGlobal' is not concurrency-safe because it is non-isolated global shared mutable state; this is an error in the Swift 6 language mode}}
-// expected-note@+3 {{convert 'mutableGlobal' to a 'let' constant to make the shared state immutable}}
-// expected-note@+2 {{restrict 'mutableGlobal' to the main actor if it will only be accessed from the main thread}}
-// expected-note@+1 {{unsafely mark 'mutableGlobal' as concurrency-safe if all accesses are protected by an external synchronization mechanism}}
-var mutableGlobal: String = "can't touch this" // expected-note 5{{var declared here}}
-
 @available(SwiftStdlib 5.1, *)
 func globalFunc() { }
 @available(SwiftStdlib 5.1, *)

test/Concurrency/concurrency_warnings.swift

@@ -1,5 +1,9 @@
-// RUN: %target-swift-frontend -strict-concurrency=complete -parse-as-library %s -emit-sil -o /dev/null -verify -disable-region-based-isolation-with-strict-concurrency
-// RUN: %target-swift-frontend -strict-concurrency=complete -parse-as-library %s -emit-sil -o /dev/null -verify
+// RUN: %empty-directory(%t)
+
+// RUN: %target-swift-frontend -emit-module -emit-module-path %t/GlobalVariables.swiftmodule -module-name GlobalVariables %S/Inputs/GlobalVariables.swift -disable-availability-checking -parse-as-library
+
+// RUN: %target-swift-frontend -I %t -strict-concurrency=complete -parse-as-library %s -emit-sil -o /dev/null -verify -disable-region-based-isolation-with-strict-concurrency
+// RUN: %target-swift-frontend -I %t -strict-concurrency=complete -parse-as-library %s -emit-sil -o /dev/null -verify
 
 // REQUIRES: concurrency
 // REQUIRES: asserts
@@ -12,12 +16,7 @@ let rs = GlobalCounter() // expected-warning {{let 'rs' is not concurrency-safe
 // expected-note@-1 {{restrict 'rs' to the main actor if it will only be accessed from the main thread}}
 // expected-note@-2 {{unsafely mark 'rs' as concurrency-safe if all accesses are protected by an external synchronization mechanism}}
 
-
-var globalInt = 17 // expected-warning {{var 'globalInt' is not concurrency-safe because it is non-isolated global shared mutable state; this is an error in the Swift 6 language mode}}
-// expected-note@-1 {{restrict 'globalInt' to the main actor if it will only be accessed from the main thread}}
-// expected-note@-2 2{{var declared here}}
-// expected-note@-3 {{unsafely mark 'globalInt' as concurrency-safe if all accesses are protected by an external synchronization mechanism}}
-// expected-note@-4 {{convert 'globalInt' to a 'let' constant to make the shared state immutable}}
+import GlobalVariables
 
 class MyError: Error { // expected-warning{{non-final class 'MyError' cannot conform to 'Sendable'; use '@unchecked Sendable'}}
   var storage = 0 // expected-warning{{stored property 'storage' of 'Sendable'-conforming class 'MyError' is mutable}}

test/Concurrency/flow_isolation.swift

@@ -521,9 +521,8 @@ struct CardboardBox<T> {
 @available(SwiftStdlib 5.1, *)
 var globalVar: EscapeArtist? // expected-warning {{var 'globalVar' is not concurrency-safe because it is non-isolated global shared mutable state; this is an error in the Swift 6 language mode}}
 // expected-note@-1 {{restrict 'globalVar' to the main actor if it will only be accessed from the main thread}}
-// expected-note@-2 2 {{var declared here}}
-// expected-note@-3 {{unsafely mark 'globalVar' as concurrency-safe if all accesses are protected by an external synchronization mechanism}}
-// expected-note@-4 {{convert 'globalVar' to a 'let' constant to make the shared state immutable}}
+// expected-note@-2 {{unsafely mark 'globalVar' as concurrency-safe if all accesses are protected by an external synchronization mechanism}}
+// expected-note@-3 {{convert 'globalVar' to a 'let' constant to make the shared state immutable}}
 
 @available(SwiftStdlib 5.1, *)
 actor EscapeArtist {
@@ -532,11 +531,9 @@ actor EscapeArtist {
     init(attempt1: Bool) {
         self.x = 0
 
-        // expected-note@+2 {{after making a copy of 'self', only non-isolated properties of 'self' can be accessed from this init}}
-        // expected-warning@+1 {{reference to var 'globalVar' is not concurrency-safe because it involves shared mutable state}}
+        // expected-note@+1 {{after making a copy of 'self', only non-isolated properties of 'self' can be accessed from this init}}
         globalVar = self
 
-        // expected-warning@+1 {{reference to var 'globalVar' is not concurrency-safe because it involves shared mutable state}}
         Task { await globalVar!.isolatedMethod() }
 
         if self.x == 0 {  // expected-warning {{cannot access property 'x' here in non-isolated initializer; this is an error in the Swift 6 language mode}}

test/Concurrency/freestanding_top_level.swift

@@ -1,12 +1,11 @@
 // RUN: %target-swift-frontend -concurrency-model=task-to-thread -typecheck  -verify %s
 // RUN: %target-swift-frontend -concurrency-model=task-to-thread -typecheck  -verify -verify-additional-prefix complete- -strict-concurrency=complete %s
 
-// expected-complete-warning@+5 {{var 'global' is not concurrency-safe because it is non-isolated global shared mutable state; this is an error in the Swift 6 language mode}}
-// expected-complete-note@+4 {{restrict 'global' to the main actor if it will only be accessed from the main thread}}{{1-1=@MainActor }}
-// expected-complete-note@+3 {{var declared here}}
+// expected-complete-warning@+4 {{var 'global' is not concurrency-safe because it is non-isolated global shared mutable state; this is an error in the Swift 6 language mode}}
+// expected-complete-note@+3 {{restrict 'global' to the main actor if it will only be accessed from the main thread}}{{1-1=@MainActor }}
 // expected-complete-note@+2 {{unsafely mark 'global' as concurrency-safe if all accesses are protected by an external synchronization mechanism}}{{1-1=nonisolated(unsafe) }}
 // expected-complete-note@+1 {{convert 'global' to a 'let' constant to make the shared state immutable}}{{1-4=let}}
 var global = 10
 
-// expected-complete-warning@+1 {{reference to var 'global' is not concurrency-safe because it involves shared mutable state; this is an error in the Swift 6 language mode}}
+// No warning because we're in the same module.
 print(global)

test/Concurrency/global_variables.swift

@@ -60,9 +60,8 @@ struct TestStatics {
   static let immutableInferredSendable = 0
   static var mutable = 0 // expected-error{{static property 'mutable' is not concurrency-safe because it is non-isolated global shared mutable state}}
   // expected-note@-1{{convert 'mutable' to a 'let' constant to make the shared state immutable}}
-  // expected-note@-2{{static property declared here}}
-  // expected-note@-3{{unsafely mark 'mutable' as concurrency-safe if all accesses are protected by an external synchronization mechanism}}
-  // expected-note@-4{{restrict 'mutable' to the main actor if it will only be accessed from the main thread}}
+  // expected-note@-2{{unsafely mark 'mutable' as concurrency-safe if all accesses are protected by an external synchronization mechanism}}
+  // expected-note@-3{{restrict 'mutable' to the main actor if it will only be accessed from the main thread}}
   static var computedProperty: Int { 0 } // computed property that, though static, has no storage so is not a global
   @TestWrapper static var wrapped: Int // expected-error{{static property 'wrapped' is not concurrency-safe because it is non-isolated global shared mutable state}}
   // expected-note@-1{{convert 'wrapped' to a 'let' constant to make the shared state immutable}}{{23-26=let}}
@@ -79,7 +78,7 @@ public actor TestPublicActor {
 func f() {
   print(TestStatics.immutableExplicitSendable)
   print(TestStatics.immutableInferredSendable)
-  print(TestStatics.mutable) // expected-error{{reference to static property 'mutable' is not concurrency-safe because it involves shared mutable state}}
+  print(TestStatics.mutable)
   print(Globals.actorInteger) // expected-error{{main actor-isolated static property 'actorInteger' can not be referenced from global actor 'TestGlobalActor'}}
 }