[region-isolation] Perform checking of non-Sendable results using rbi rather than Sema.

include/swift/AST/DiagnosticsSIL.def

@@ -1098,6 +1098,28 @@ NOTE(regionbasedisolation_out_sending_cannot_be_actor_isolated_note_named, none,
       "returning %1 %0 risks causing data races since the caller assumes that %0 can be safely sent to other isolation domains",
       (Identifier, StringRef))
 
+//===
+// non-Sendable Results
+
+// Example: returning main-actor isolated result to a custom-actor isolated context risks causing data races
+ERROR(rbi_isolation_crossing_result, none,
+      "non-Sendable %0-typed result can not be returned from %1 %kind2 to %3 context",
+      (Type, ActorIsolation, const ValueDecl *, ActorIsolation))
+ERROR(rbi_isolation_crossing_result_no_decl, none,
+      "non-Sendable %0-typed result can not be returned from %1 function to %2 context",
+      (Type, ActorIsolation, ActorIsolation))
+NOTE(rbi_non_sendable_nominal,none,
+     "%kind0 does not conform to the 'Sendable' protocol",
+      (const ValueDecl *))
+NOTE(rbi_nonsendable_function_type,none,
+     "a function type must be marked '@Sendable' to conform to 'Sendable'", ())
+NOTE(rbi_add_nominal_sendable_conformance,none,
+     "consider making %kind0 conform to the 'Sendable' protocol",
+     (const ValueDecl *))
+NOTE(rbi_add_generic_parameter_sendable_conformance,none,
+     "consider making generic parameter %0 conform to the 'Sendable' protocol",
+     (Type))
+
 //===----------------------------------------------------------------------===//
 //                           MARK: Misc Diagnostics
 //===----------------------------------------------------------------------===//

include/swift/SILOptimizer/Utils/PartitionOpError.def

@@ -59,4 +59,8 @@ PARTITION_OP_ERROR(InOutSendingNotDisconnectedAtExit)
 /// to our user so that we can emit that error as we process.
 PARTITION_OP_ERROR(UnknownCodePattern)
 
+/// Used to signify that an isolation crossing function is returning a
+/// non-Sendable value.
+PARTITION_OP_ERROR(NonSendableIsolationCrossingResult)
+
 #undef PARTITION_OP_ERROR

include/swift/SILOptimizer/Utils/PartitionUtils.h

@@ -462,6 +462,14 @@ enum class PartitionOpKind : uint8_t {
   ///
   /// Takes one parameter, the inout parameter that we need to check.
   InOutSendingAtFunctionExit,
+
+  /// This is the result of an isolation crossing apply site. We need to emit a
+  /// special error since we never allow this.
+  ///
+  /// DISCUSSION: This is actually just a form of "send". Sadly, we can not use
+  /// "send" directly since "send" expects a SILOperand and these are values. So
+  /// to work around the API issue, we have to use a different, specific entry.
+  NonSendableIsolationCrossingResult,
 };
 
 /// PartitionOp represents a primitive operation that can be performed on
@@ -574,6 +582,12 @@ class PartitionOp {
                        sourceInst);
   }
 
+  static PartitionOp
+  NonSendableIsolationCrossingResult(Element elt, SILInstruction *sourceInst) {
+    return PartitionOp(PartitionOpKind::NonSendableIsolationCrossingResult, elt,
+                       sourceInst);
+  }
+
   bool operator==(const PartitionOp &other) const {
     return opKind == other.opKind && opArgs == other.opArgs &&
            source == other.source;
@@ -1053,6 +1067,22 @@ class PartitionOpError {
     }
   };
 
+  struct NonSendableIsolationCrossingResultError {
+    const PartitionOp *op;
+
+    Element returnValueElement;
+
+    NonSendableIsolationCrossingResultError(const PartitionOp &op,
+                                            Element returnValue)
+        : op(&op), returnValueElement(returnValue) {}
+
+    void print(llvm::raw_ostream &os, RegionAnalysisValueMap &valueMap) const;
+
+    SWIFT_DEBUG_DUMPER(dump(RegionAnalysisValueMap &valueMap)) {
+      print(llvm::dbgs(), valueMap);
+    }
+  };
+
 #define PARTITION_OP_ERROR(NAME)                                               \
   static_assert(std::is_copy_constructible_v<NAME##Error>,                     \
                 #NAME " must be copy constructable");
@@ -1482,8 +1512,15 @@ struct PartitionOpEvaluator {
 
       // Then emit an unknown code pattern error.
       return handleError(UnknownCodePatternError(op));
+    case PartitionOpKind::NonSendableIsolationCrossingResult:
+      // Grab the dynamic dataflow isolation information for our element's
+      // region.
+      Region region = p.getRegion(op.getOpArgs()[0]);
+
+      // Then emit the error.
+      return handleError(
+          NonSendableIsolationCrossingResultError(op, op.getOpArgs()[0]));
     }
-
     llvm_unreachable("Covered switch isn't covered?!");
   }
 

lib/SILOptimizer/Analysis/RegionAnalysis.cpp

@@ -1526,6 +1526,12 @@ struct PartitionOpBuilder {
         PartitionOp::UnknownPatternError(lookupValueID(value), currentInst));
   }
 
+  void addNonSendableIsolationCrossingResultError(SILValue value) {
+    currentInstPartitionOps.emplace_back(
+        PartitionOp::NonSendableIsolationCrossingResult(lookupValueID(value),
+                                                        currentInst));
+  }
+
   SWIFT_DEBUG_DUMP { print(llvm::dbgs()); }
 
   void print(llvm::raw_ostream &os) const;
@@ -2394,14 +2400,58 @@ class PartitionOpTranslator {
       handleSILOperands(applySite.getOperandsWithoutIndirectResults());
     }
 
-    // non-sendable results can't be returned from cross-isolation calls without
-    // a diagnostic emitted elsewhere. Here, give them a fresh value for better
-    // diagnostics hereafter
+    // Create a new assign fresh for each one of our values and unless our
+    // return value is sending, emit an extra error bit on the results that are
+    // non-Sendable.
     SmallVector<SILValue, 8> applyResults;
     getApplyResults(*applySite, applyResults);
-    for (auto result : applyResults)
-      if (auto value = tryToTrackValue(result))
+
+    auto substCalleeType = applySite.getSubstCalleeType();
+
+    // Today, all values in result info are sending or none are. So this is a
+    // safe to check that we have a sending result. In the future if we allow
+    // for sending to vary, then this code will need to be updated to vary with
+    // each result.
+    auto results = substCalleeType->getResults();
+    auto *applyExpr = applySite->getLoc().getAsASTNode<ApplyExpr>();
+
+    // We only emit the error if we do not have a sending result and if our
+    // callee isn't nonisolated.
+    //
+    // DISCUSSION: If our callee is non-isolated, we know that the value must
+    // have been returned as a non-sent disconnected value. The reason why this
+    // is different from a sending result is that the result may be part of the
+    // region of the operands while the sending result will not be. In either
+    // case though, we do not want to emit the error.
+    bool emitIsolationCrossingResultError =
+        (results.empty() || !results[0].hasOption(SILResultInfo::IsSending)) &&
+        // We have to check if we actually have an apply expr since we may not
+        // have one if we are processing a SIL test case since SIL does not have
+        // locations (which is how we grab our AST information).
+        !(applyExpr && applyExpr->getIsolationCrossing()
+                           ->getCalleeIsolation()
+                           .isNonisolated());
+
+    for (auto result : applyResults) {
+      if (auto value = tryToTrackValue(result)) {
         builder.addAssignFresh(value->getRepresentative().getValue());
+        if (emitIsolationCrossingResultError)
+          builder.addNonSendableIsolationCrossingResultError(
+              value->getRepresentative().getValue());
+      }
+    }
+
+    // If we are supposed to emit isolation crossing errors, go through our
+    // parameters and add the error on any indirect results that are
+    // non-Sendable.
+    if (emitIsolationCrossingResultError) {
+      for (auto result : applySite.getIndirectSILResults()) {
+        if (auto value = tryToTrackValue(result)) {
+          builder.addNonSendableIsolationCrossingResultError(
+              value->getRepresentative().getValue());
+        }
+      }
+    }
   }
 
   template <typename DestValues>