[Concurrency] Don't skip pattern bindings with multiple vars when inferring the

isolation of implicit initializers.

(cherry picked from commit cc1fd1c)

Author: hborla

lib/Sema/CodeSynthesis.cpp

@@ -354,62 +354,64 @@ static ConstructorDecl *createImplicitConstructor(NominalTypeDecl *decl,
     VarDecl *previousVar = nullptr;
 
     for (auto member : decl->getImplementationContext()->getAllMembers()) {
+      bool hasError = false;
       auto pbd = dyn_cast<PatternBindingDecl>(member);
       if (!pbd || pbd->isStatic())
         continue;
 
-      auto *var = pbd->getSingleVar();
-      if (!var) {
-        shouldAddNonisolated = false;
-        break;
-      }
-
-      auto i = pbd->getPatternEntryIndexForVarDecl(var);
-      if (pbd->isInitializerSubsumed(i))
-        continue;
-
-      ActorIsolation initIsolation;
-      if (var->hasInitAccessor()) {
-        // Init accessors share the actor isolation of the property;
-        // the accessor body can call anything in that isolation domain,
-        // and we don't attempt to infer when the isolation isn't
-        // necessary.
-        initIsolation = getActorIsolation(var);
-      } else {
-        initIsolation = var->getInitializerIsolation();
-      }
+      for (auto i : range(pbd->getNumPatternEntries())) {
+        if (pbd->isInitializerSubsumed(i))
+          continue;
+
+        auto *var = pbd->getAnchoringVarDecl(i);
+
+        ActorIsolation initIsolation;
+        if (var->hasInitAccessor()) {
+          // Init accessors share the actor isolation of the property;
+          // the accessor body can call anything in that isolation domain,
+          // and we don't attempt to infer when the isolation isn't
+          // necessary.
+          initIsolation = getActorIsolation(var);
+        } else {
+          initIsolation = var->getInitializerIsolation();
+        }
 
-      auto type = var->getTypeInContext();
-      auto isolation = getActorIsolation(var);
-      if (isolation.isGlobalActor()) {
-        if (!isSendableType(decl->getModuleContext(), type) ||
-            initIsolation.isGlobalActor()) {
-          // If different isolated stored properties require different
-          // global actors, it is impossible to initialize this type.
-          if (existingIsolation != isolation) {
-            ctx.Diags.diagnose(decl->getLoc(),
-                diag::conflicting_stored_property_isolation,
-                ICK == ImplicitConstructorKind::Memberwise,
-                decl->getDeclaredType(), existingIsolation, isolation)
-              .warnUntilSwiftVersion(6);
-            if (previousVar) {
-              previousVar->diagnose(
+        auto type = var->getTypeInContext();
+        auto isolation = getActorIsolation(var);
+        if (isolation.isGlobalActor()) {
+          if (!isSendableType(decl->getModuleContext(), type) ||
+              initIsolation.isGlobalActor()) {
+            // If different isolated stored properties require different
+            // global actors, it is impossible to initialize this type.
+            if (existingIsolation != isolation) {
+              ctx.Diags.diagnose(decl->getLoc(),
+                  diag::conflicting_stored_property_isolation,
+                  ICK == ImplicitConstructorKind::Memberwise,
+                  decl->getDeclaredType(), existingIsolation, isolation)
+                .warnUntilSwiftVersion(6);
+              if (previousVar) {
+                previousVar->diagnose(
+                    diag::property_requires_actor,
+                    previousVar->getDescriptiveKind(),
+                    previousVar->getName(), existingIsolation);
+              }
+              var->diagnose(
                   diag::property_requires_actor,
-                  previousVar->getDescriptiveKind(),
-                  previousVar->getName(), existingIsolation);
+                  var->getDescriptiveKind(),
+                  var->getName(), isolation);
+              hasError = true;
+              break;
             }
-            var->diagnose(
-                diag::property_requires_actor,
-                var->getDescriptiveKind(),
-                var->getName(), isolation);
-            break;
-          }
 
-          existingIsolation = isolation;
-          previousVar = var;
-          shouldAddNonisolated = false;
+            existingIsolation = isolation;
+            previousVar = var;
+            shouldAddNonisolated = false;
+          }
         }
       }
+
+      if (hasError)
+        break;
     }
 
     if (shouldAddNonisolated) {

test/Concurrency/isolated_default_arguments.swift

@@ -220,10 +220,21 @@ class C3 {
   var y = 0
 }
 
+@MainActor class MultipleVars {
+  var (x, y) = (0, 0)
+}
+
 func callDefaultInit() async {
   _ = C2()
   _ = NonIsolatedInit()
   _ = NonIsolatedInit(x: 10)
+  _ = MultipleVars()
+}
+
+// expected-warning@+1 {{default initializer for 'MultipleVarsInvalid' cannot be both nonisolated and main actor-isolated; this is an error in Swift 6}}
+class MultipleVarsInvalid {
+  // expected-note@+1 {{initializer for property 'x' is main actor-isolated}}
+  @MainActor var (x, y) = (requiresMainActor(), requiresMainActor())
 }
 
 @propertyWrapper