[region-isolation] When dumping send never-sendable errors, dump the isolated value and its name if we can compute it.

This just makes it quicker/easier to diagnose inability to infer the appropriate
name of an isolated value and what the isolated value itself is.

Author: gottesmm

include/swift/SILOptimizer/Utils/SILIsolationInfo.h

@@ -323,6 +323,12 @@ class SILIsolationInfo {
     return (kind == Task || kind == Actor) && bool(isolatedValue);
   }
 
+  SILValue maybeGetIsolatedValue() const {
+    if (!hasIsolatedValue())
+      return {};
+    return getIsolatedValue();
+  }
+
   static SILIsolationInfo getDisconnected(bool isUnsafeNonIsolated) {
     return {Kind::Disconnected,
             isUnsafeNonIsolated ? Flag::UnsafeNonIsolated : Flag::None};

lib/SILOptimizer/Mandatory/TransferNonSendable.cpp

@@ -2217,7 +2217,16 @@ struct DiagnosticEvaluator final
                      << *info->getValueMap().getRepresentative(transferredVal)
                      << "        Dynamic Isolation Region: ";
         isolationRegionInfo.printForOneLineLogging(llvm::dbgs());
-        llvm::dbgs() << '\n');
+        llvm::dbgs() << '\n';
+        if (auto isolatedValue = isolationRegionInfo->maybeGetIsolatedValue()) {
+          llvm::dbgs() << "        Isolated Value: " << isolatedValue;
+          auto name = inferNameHelper(isolatedValue);
+          llvm::dbgs() << "        Isolated Value Name: "
+                       << (name.has_value() ? name->get() : "none") << '\n';
+        } else {
+          llvm::dbgs() << "        Isolated Value: none\n";
+        }
+    );
     auto *self = const_cast<DiagnosticEvaluator *>(this);
     auto nonTransferrableValue =
         info->getValueMap().getRepresentative(transferredVal);