carry the info into the solver

Author: ktoso

include/swift/Sema/ConstraintSystem.h

@@ -1312,6 +1312,9 @@ class Solution {
   /// The set of parameters that have been inferred to be 'isolated'.
   llvm::SmallVector<ParamDecl *, 2> isolatedParams;
 
+  /// The set of parameters that have been inferred to be '_local'.
+  llvm::SmallVector<ParamDecl *, 2> distributedKnownLocalParams;
+
   /// The set of functions that have been transformed by a result builder.
   llvm::MapVector<AnyFunctionRef, AppliedBuilderTransform>
       resultBuilderTransformed;
@@ -2675,7 +2678,7 @@ class ConstraintSystem {
   llvm::SmallSetVector<ParamDecl *, 2> isolatedParams;
 
   /// The set of DistributedActor parameters that have been inferred
-  /// to be known to be local.
+  /// to be known to be '_local'.
   llvm::SmallSetVector<ParamDecl *, 2> distributedKnownLocalParams;
 
   /// Maps closure parameters to type variables.

lib/Sema/CSApply.cpp

@@ -7963,7 +7963,8 @@ bool ExprRewriter::requiresDistributedThunk(Expr *base, SourceLoc memberLoc,
            llvm::is_contained(solution.isolatedParams, P);
   },
     [&](ParamDecl *P) {
-    return P->isDistributedKnownToBeLocal(); // TODO: need the solution too?
+    return P->isDistributedKnownToBeLocal() ||
+        llvm::is_contained(solution.distributedKnownLocalParams, P);
   });
 
   // Adjust the declaration context to the innermost context that is neither

lib/Sema/CSClosure.cpp

@@ -1656,6 +1656,12 @@ SolutionApplicationToFunctionResult ConstraintSystem::applySolution(
         param->setIsolated(true);
     }
 
+    // Find any '_local' parameters in this closure and mark them as isolated.
+    for (auto param : solution.distributedKnownLocalParams) {
+      if (param->getDeclContext() == closure)
+        param->setDistributedKnownToBeLocal(true);
+    }
+
     // Coerce the result type, if it was written explicitly.
     if (closure->hasExplicitResultType()) {
       closure->setExplicitResultType(closureFnType->getResult());

lib/Sema/CSSimplify.cpp

@@ -9870,8 +9870,9 @@ bool ConstraintSystem::resolveClosure(TypeVariableType *typeVar,
           // an 'isolated' param is also implicitly '_local',
           // since in order to run "on" an actor, it must be a real local instance.
           distributedKnownLocalParams.insert(paramDecl);
-        } else if (contextualParam->isDistributedKnownToBeLocal() &&
-                   !flags.isDistributedKnownToBeLocal() && paramDecl) {
+        }
+        if (contextualParam->isDistributedKnownToBeLocal() &&
+            !flags.isDistributedKnownToBeLocal() && paramDecl) {
           distributedKnownLocalParams.insert(paramDecl);
         }
 

lib/Sema/CSSolver.cpp

@@ -182,6 +182,7 @@ Solution ConstraintSystem::finalize() {
   solution.solutionApplicationTargets = solutionApplicationTargets;
   solution.caseLabelItems = caseLabelItems;
   solution.isolatedParams.append(isolatedParams.begin(), isolatedParams.end());
+  solution.distributedKnownLocalParams.append(distributedKnownLocalParams.begin(), distributedKnownLocalParams.end());
 
   for (const auto &transformed : resultBuilderTransformed) {
     solution.resultBuilderTransformed.insert(transformed);
@@ -295,6 +296,10 @@ void ConstraintSystem::applySolution(const Solution &solution) {
     isolatedParams.insert(param);
   }
 
+  for (auto param : solution.distributedKnownLocalParams) {
+    distributedKnownLocalParams.insert(param);
+  }
+
   for (const auto &transformed : solution.resultBuilderTransformed) {
     resultBuilderTransformed.insert(transformed);
   }
@@ -535,6 +540,7 @@ ConstraintSystem::SolverScope::SolverScope(ConstraintSystem &cs)
   numSolutionApplicationTargets = cs.solutionApplicationTargets.size();
   numCaseLabelItems = cs.caseLabelItems.size();
   numIsolatedParams = cs.isolatedParams.size();
+  numDistributedKnownLocalParams = cs.distributedKnownLocalParams.size();
   numImplicitValueConversions = cs.ImplicitValueConversions.size();
   numArgumentLists = cs.ArgumentLists.size();
   numImplicitCallAsFunctionRoots = cs.ImplicitCallAsFunctionRoots.size();
@@ -646,6 +652,9 @@ ConstraintSystem::SolverScope::~SolverScope() {
   // Remove any isolated parameters.
   truncate(cs.isolatedParams, numIsolatedParams);
 
+  // Remove any distributed known-to-be-local parameters.
+  truncate(cs.distributedKnownLocalParams, numDistributedKnownLocalParams);
+
   // Remove any implicit value conversions.
   truncate(cs.ImplicitValueConversions, numImplicitValueConversions);
 

lib/Sema/TypeCheckType.cpp

@@ -3706,7 +3706,7 @@ TypeResolver::resolveDistributedKnownToBeLocal(DistributedKnownToBeLocalTypeRepr
 
   // TODO(distributed): more diagnosis here, prevent from use in props, enums etc
 
-  // isolated parameters must be of 'distributed actor' type
+  // '_local' parameters must be of 'distributed actor' type
   if (!type->hasTypeParameter() &&
       !type->isDistributedActor() &&
       !type->hasError()) {

lib/Serialization/ModuleFormat.h

@@ -58,7 +58,7 @@ const uint16_t SWIFTMODULE_VERSION_MAJOR = 0;
 /// describe what change you made. The content of this comment isn't important;
 /// it just ensures a conflict if two people change the module format.
 /// Don't worry about adhering to the 80-column limit for this line.
-const uint16_t SWIFTMODULE_VERSION_MINOR = 694; // add @objc protocol methods to objc method tables
+const uint16_t SWIFTMODULE_VERSION_MINOR = 695; // add '_local' for distributed actors to mark "known to be local"
 
 /// A standard hash seed used for all string hashes in a serialized module.
 ///