diff --git a/include/swift/AST/DiagnosticsSIL.def b/include/swift/AST/DiagnosticsSIL.def
index 8df0fe8afc8..34b1577b3e3 100644
--- a/include/swift/AST/DiagnosticsSIL.def
+++ b/include/swift/AST/DiagnosticsSIL.def
@@ -1005,11 +1005,11 @@ NOTE(regionbasedisolation_type_use_after_send_callee, none,
      (Type, StringRef, const ValueDecl *, StringRef))
 
 NOTE(regionbasedisolation_named_info_send_yields_race, none,
-     "sending %1%0 to %2 callee risks causing data races between %2 and local %3 uses",
-     (Identifier, StringRef, StringRef, StringRef))
+     "sending %select{%2 |}0%1 to %3 callee risks causing data races between %3 and local %4 uses",
+     (bool, Identifier, StringRef, StringRef, StringRef))
 NOTE(regionbasedisolation_named_info_send_yields_race_callee, none,
-     "sending %1%0 to %2 %kind3 risks causing data races between %2 and local %4 uses",
-     (Identifier, StringRef, StringRef, const ValueDecl *, StringRef))
+     "sending %select{%2 |}0%1 to %3 %kind4 risks causing data races between %3 and local %5 uses",
+     (bool, Identifier, StringRef, StringRef, const ValueDecl *, StringRef))
 
 // Use after send closure.
 NOTE(regionbasedisolation_type_isolated_capture_yields_race, none,
@@ -1025,8 +1025,8 @@ NOTE(regionbasedisolation_named_value_used_after_explicit_sending, none,
       "%0 used after being passed as a 'sending' parameter; Later uses could race",
       (Identifier))
 NOTE(regionbasedisolation_named_isolated_closure_yields_race, none,
-      "%0%1 is captured by a %2 closure. %2 uses in closure may race against later %3 uses",
-      (StringRef, Identifier, StringRef, StringRef))
+      "%select{%1 |}0%2 is captured by a %3 closure. %3 uses in closure may race against later %4 uses",
+      (bool, StringRef, Identifier, StringRef, StringRef))
 
 NOTE(regionbasedisolation_typed_use_after_sending, none,
       "Passing value of non-Sendable type %0 as a 'sending' argument risks causing races in between local and caller code",
@@ -1039,19 +1039,19 @@ NOTE(regionbasedisolation_typed_use_after_sending_callee, none,
 // Sending Never Sendable Emitter
 
 NOTE(regionbasedisolation_named_send_never_sendable, none,
-      "sending %1%0 to %2 callee risks causing data races between %2 and %3 uses",
-      (Identifier, StringRef, StringRef, StringRef))
+      "sending %select{%2 |}0%1 to %3 callee risks causing data races between %3 and %4 uses",
+      (bool, Identifier, StringRef, StringRef, StringRef))
 NOTE(regionbasedisolation_named_send_never_sendable_callee, none,
-      "sending %1%0 to %2 %kind3 risks causing data races between %2 and %4 uses",
-      (Identifier, StringRef, StringRef, const ValueDecl *, StringRef))
+      "sending %select{%2 |}0%1 to %3 %kind4 risks causing data races between %3 and %5 uses",
+      (bool, Identifier, StringRef, StringRef, const ValueDecl *, StringRef))
 
 NOTE(regionbasedisolation_named_send_into_sending_param, none,
-     "%0%1 is passed as a 'sending' parameter; Uses in callee may race with "
-     "later %0uses",
-     (StringRef, Identifier))
+     "%select{%1 |}0%2 is passed as a 'sending' parameter; Uses in callee may race with "
+     "later %1 uses",
+     (bool, StringRef, Identifier))
 NOTE(regionbasedisolation_named_nosend_send_into_result, none,
-     "%0%1 cannot be a 'sending' result. %2 uses may race with caller uses",
-     (StringRef, Identifier, StringRef))
+     "%select{%1 |}0%2 cannot be a 'sending' result. %3 uses may race with caller uses",
+     (bool, StringRef, Identifier, StringRef))
 NOTE(regionbasedisolation_typed_tns_passed_to_sending, none,
      "Passing %0 value of non-Sendable type %1 as a 'sending' parameter risks "
      "causing races inbetween %0 uses and uses reachable from the callee",
@@ -1109,10 +1109,10 @@ NOTE(regionbasedisolation_inout_sending_must_be_reinitialized, none,
      "'inout sending' parameter must be reinitialized before function exit with a non-actor-isolated value",
      ())
 ERROR(regionbasedisolation_inout_sending_cannot_be_actor_isolated, none,
-      "'inout sending' parameter %0 cannot be %1at end of function",
+      "'inout sending' parameter %0 cannot be %1 at end of function",
       (Identifier, StringRef))
 NOTE(regionbasedisolation_inout_sending_cannot_be_actor_isolated_note, none,
-      "%1%0 risks causing races in between %1uses and caller uses since caller assumes value is not actor isolated",
+      "%1 %0 risks causing races in between %1 uses and caller uses since caller assumes value is not actor isolated",
       (Identifier, StringRef))
 
 //===
diff --git a/include/swift/AST/Identifier.h b/include/swift/AST/Identifier.h
index 6a773015106..1e36b893cde 100644
--- a/include/swift/AST/Identifier.h
+++ b/include/swift/AST/Identifier.h
@@ -230,7 +230,7 @@ public:
 private:
   bool isOperatorSlow() const;
 };
-  
+
 class DeclName;
 class DeclNameRef;
 class ObjCSelector;
diff --git a/include/swift/SILOptimizer/Utils/SILIsolationInfo.h b/include/swift/SILOptimizer/Utils/SILIsolationInfo.h
index e82d23284f8..4f5e15c20ad 100644
--- a/include/swift/SILOptimizer/Utils/SILIsolationInfo.h
+++ b/include/swift/SILOptimizer/Utils/SILIsolationInfo.h
@@ -332,8 +332,16 @@ public:
   /// form of diagnostic than other cases.
   void printForCodeDiagnostic(SILFunction *fn, llvm::raw_ostream &os) const;
 
+  /// Overload of printForCodeDiagnostics that returns an interned StringRef
+  /// owned by the AST.
+  StringRef printForCodeDiagnostic(SILFunction *fn) const;
+
   void printForDiagnostics(SILFunction *fn, llvm::raw_ostream &os) const;
 
+  /// Overload of printForDiagnostics that returns an interned StringRef owned
+  /// by the AST.
+  StringRef printForDiagnostics(SILFunction *fn) const;
+
   SWIFT_DEBUG_DUMPER(dumpForDiagnostics(SILFunction *fn)) {
     printForDiagnostics(fn, llvm::dbgs());
     llvm::dbgs() << '\n';
@@ -524,6 +532,12 @@ public:
       SILFunction *fn, ActorIsolation iso, llvm::raw_ostream &os,
       StringRef openingQuotationMark = "'", bool asNoun = false);
 
+  /// Overload for printActorIsolationForDiagnostics that produces a StringRef.
+  static StringRef
+  printActorIsolationForDiagnostics(SILFunction *fn, ActorIsolation iso,
+                                    StringRef openingQuotationMark = "'",
+                                    bool asNoun = false);
+
   void Profile(llvm::FoldingSetNodeID &id) const;
 
 private:
@@ -593,6 +607,10 @@ public:
     innerInfo.printForDiagnostics(fn, os);
   }
 
+  StringRef printForDiagnostics(SILFunction *fn) const {
+    return innerInfo.printForDiagnostics(fn);
+  }
+
   SWIFT_DEBUG_DUMPER(dumpForDiagnostics(SILFunction *fn)) {
     innerInfo.dumpForDiagnostics(fn);
   }
@@ -601,6 +619,10 @@ public:
     innerInfo.printForCodeDiagnostic(fn, os);
   }
 
+  StringRef printForCodeDiagnostic(SILFunction *fn) const {
+    return innerInfo.printForCodeDiagnostic(fn);
+  }
+
   void printForOneLineLogging(SILFunction *fn, llvm::raw_ostream &os) const {
     innerInfo.printForOneLineLogging(fn, os);
   }
diff --git a/lib/SILOptimizer/Mandatory/SendNonSendable.cpp b/lib/SILOptimizer/Mandatory/SendNonSendable.cpp
index af2372fcb04..6e325016bad 100644
--- a/lib/SILOptimizer/Mandatory/SendNonSendable.cpp
+++ b/lib/SILOptimizer/Mandatory/SendNonSendable.cpp
@@ -686,37 +686,24 @@ public:
         .limitBehaviorIf(getBehaviorLimit());
 
     // Then emit the note with greater context.
-    SmallString<64> descriptiveKindStr;
-    {
-      if (!namedValuesIsolationInfo.isDisconnected()) {
-        llvm::raw_svector_ostream os(descriptiveKindStr);
-        namedValuesIsolationInfo.printForDiagnostics(getFunction(), os);
-        os << ' ';
-      }
-    }
-
-    SmallString<64> calleeIsolationStr;
-    {
-      llvm::raw_svector_ostream os(calleeIsolationStr);
-      SILIsolationInfo::printActorIsolationForDiagnostics(
-          getFunction(), isolationCrossing.getCalleeIsolation(), os);
-    }
-
-    SmallString<64> callerIsolationStr;
-    {
-      llvm::raw_svector_ostream os(callerIsolationStr);
-      SILIsolationInfo::printActorIsolationForDiagnostics(
-          getFunction(), isolationCrossing.getCallerIsolation(), os);
-    }
+    auto descriptiveKindStr =
+        namedValuesIsolationInfo.printForDiagnostics(getFunction());
+    auto calleeIsolationStr =
+        SILIsolationInfo::printActorIsolationForDiagnostics(
+            getFunction(), isolationCrossing.getCalleeIsolation());
+    auto callerIsolationStr =
+        SILIsolationInfo::printActorIsolationForDiagnostics(
+            getFunction(), isolationCrossing.getCallerIsolation());
 
+    bool isDisconnected = namedValuesIsolationInfo.isDisconnected();
     if (auto callee = getSendingCallee()) {
       diagnoseNote(
           loc, diag::regionbasedisolation_named_info_send_yields_race_callee,
-          name, descriptiveKindStr, calleeIsolationStr, callee.value(),
-          callerIsolationStr);
+          isDisconnected, name, descriptiveKindStr, calleeIsolationStr,
+          callee.value(), callerIsolationStr);
     } else {
       diagnoseNote(loc, diag::regionbasedisolation_named_info_send_yields_race,
-                   name, descriptiveKindStr, calleeIsolationStr,
+                   isDisconnected, name, descriptiveKindStr, calleeIsolationStr,
                    callerIsolationStr);
     }
     emitRequireInstDiagnostics();
@@ -733,33 +720,20 @@ public:
         .limitBehaviorIf(getBehaviorLimit());
 
     // Then emit the note with greater context.
-    SmallString<64> descriptiveKindStr;
-    {
-      if (!namedValuesIsolationInfo.isDisconnected()) {
-        llvm::raw_svector_ostream os(descriptiveKindStr);
-        namedValuesIsolationInfo.printForDiagnostics(getFunction(), os);
-        os << ' ';
-      }
-    }
-
-    SmallString<64> calleeIsolationStr;
-    {
-      llvm::raw_svector_ostream os(calleeIsolationStr);
-      SILIsolationInfo::printActorIsolationForDiagnostics(
-          getFunction(), isolationCrossing.getCalleeIsolation(), os);
-    }
-
-    SmallString<64> callerIsolationStr;
-    {
-      llvm::raw_svector_ostream os(callerIsolationStr);
-      SILIsolationInfo::printActorIsolationForDiagnostics(
-          getFunction(), isolationCrossing.getCallerIsolation(), os);
-    }
+    auto descriptiveKindStr =
+        namedValuesIsolationInfo.printForDiagnostics(getFunction());
+    auto calleeIsolationStr =
+        SILIsolationInfo::printActorIsolationForDiagnostics(
+            getFunction(), isolationCrossing.getCalleeIsolation());
+    auto callerIsolationStr =
+        SILIsolationInfo::printActorIsolationForDiagnostics(
+            getFunction(), isolationCrossing.getCallerIsolation());
+    bool isDisconnected = namedValuesIsolationInfo.isDisconnected();
 
     diagnoseNote(loc,
                  diag::regionbasedisolation_named_info_send_yields_race_callee,
-                 name, descriptiveKindStr, calleeIsolationStr, callee,
-                 callerIsolationStr);
+                 isDisconnected, name, descriptiveKindStr, calleeIsolationStr,
+                 callee, callerIsolationStr);
     emitRequireInstDiagnostics();
   }
 
@@ -782,19 +756,12 @@ public:
         .highlight(loc.getSourceRange())
         .limitBehaviorIf(getBehaviorLimit());
 
-    SmallString<64> calleeIsolationStr;
-    {
-      llvm::raw_svector_ostream os(calleeIsolationStr);
-      SILIsolationInfo::printActorIsolationForDiagnostics(
-          getFunction(), isolationCrossing.getCalleeIsolation(), os);
-    }
-
-    SmallString<64> callerIsolationStr;
-    {
-      llvm::raw_svector_ostream os(callerIsolationStr);
-      SILIsolationInfo::printActorIsolationForDiagnostics(
-          getFunction(), isolationCrossing.getCallerIsolation(), os);
-    }
+    auto calleeIsolationStr =
+        SILIsolationInfo::printActorIsolationForDiagnostics(
+            getFunction(), isolationCrossing.getCalleeIsolation());
+    auto callerIsolationStr =
+        SILIsolationInfo::printActorIsolationForDiagnostics(
+            getFunction(), isolationCrossing.getCallerIsolation());
 
     if (auto callee = getSendingCallee()) {
       diagnoseNote(loc, diag::regionbasedisolation_type_use_after_send_callee,
@@ -848,32 +815,19 @@ public:
         .highlight(loc.getSourceRange())
         .limitBehaviorIf(getBehaviorLimit());
 
-    SmallString<64> descriptiveKindStr;
-    {
-      if (!namedValuesIsolationInfo.isDisconnected()) {
-        llvm::raw_svector_ostream os(descriptiveKindStr);
-        namedValuesIsolationInfo.printForDiagnostics(getFunction(), os);
-        os << ' ';
-      }
-    }
-
-    SmallString<64> calleeIsolationStr;
-    {
-      llvm::raw_svector_ostream os(calleeIsolationStr);
-      SILIsolationInfo::printActorIsolationForDiagnostics(
-          getFunction(), isolationCrossing.getCalleeIsolation(), os);
-    }
-
-    SmallString<64> callerIsolationStr;
-    {
-      llvm::raw_svector_ostream os(callerIsolationStr);
-      SILIsolationInfo::printActorIsolationForDiagnostics(
-          getFunction(), isolationCrossing.getCallerIsolation(), os);
-    }
-
-    diagnoseNote(
-        loc, diag::regionbasedisolation_named_isolated_closure_yields_race,
-        descriptiveKindStr, name, calleeIsolationStr, callerIsolationStr)
+    auto descriptiveKindStr =
+        namedValuesIsolationInfo.printForDiagnostics(getFunction());
+    auto calleeIsolationStr =
+        SILIsolationInfo::printActorIsolationForDiagnostics(
+            getFunction(), isolationCrossing.getCalleeIsolation());
+    auto callerIsolationStr =
+        SILIsolationInfo::printActorIsolationForDiagnostics(
+            getFunction(), isolationCrossing.getCallerIsolation());
+    bool isDisconnected = namedValuesIsolationInfo.isDisconnected();
+    diagnoseNote(loc,
+                 diag::regionbasedisolation_named_isolated_closure_yields_race,
+                 isDisconnected, descriptiveKindStr, name, calleeIsolationStr,
+                 callerIsolationStr)
         .highlight(loc.getSourceRange());
     emitRequireInstDiagnostics();
   }
@@ -886,19 +840,12 @@ public:
         .highlight(loc.getSourceRange())
         .limitBehaviorIf(getBehaviorLimit());
 
-    SmallString<64> calleeIsolationStr;
-    {
-      llvm::raw_svector_ostream os(calleeIsolationStr);
-      SILIsolationInfo::printActorIsolationForDiagnostics(
-          getFunction(), isolationCrossing.getCalleeIsolation(), os);
-    }
-
-    SmallString<64> callerIsolationStr;
-    {
-      llvm::raw_svector_ostream os(callerIsolationStr);
-      SILIsolationInfo::printActorIsolationForDiagnostics(
-          getFunction(), isolationCrossing.getCallerIsolation(), os);
-    }
+    auto calleeIsolationStr =
+        SILIsolationInfo::printActorIsolationForDiagnostics(
+            getFunction(), isolationCrossing.getCalleeIsolation());
+    auto callerIsolationStr =
+        SILIsolationInfo::printActorIsolationForDiagnostics(
+            getFunction(), isolationCrossing.getCallerIsolation());
 
     diagnoseNote(loc,
                  diag::regionbasedisolation_type_isolated_capture_yields_race,
@@ -1419,18 +1366,11 @@ public:
         .highlight(loc.getSourceRange())
         .limitBehaviorIf(getBehaviorLimit());
 
-    SmallString<64> descriptiveKindStr;
-    {
-      llvm::raw_svector_ostream os(descriptiveKindStr);
-      getIsolationRegionInfo().printForDiagnostics(getFunction(), os);
-    }
-
-    SmallString<64> calleeIsolationStr;
-    {
-      llvm::raw_svector_ostream os(calleeIsolationStr);
-      SILIsolationInfo::printActorIsolationForDiagnostics(
-          getFunction(), crossing.getCalleeIsolation(), os);
-    }
+    auto descriptiveKindStr =
+        getIsolationRegionInfo().printForDiagnostics(getFunction());
+    auto calleeIsolationStr =
+        SILIsolationInfo::printActorIsolationForDiagnostics(
+            getFunction(), crossing.getCalleeIsolation());
 
     if (auto callee = getSendingCallee()) {
       diagnoseNote(
@@ -1447,32 +1387,20 @@ public:
   void emitNamedFunctionArgumentClosure(SILLocation loc, Identifier name,
                                         ApplyIsolationCrossing crossing) {
     emitNamedOnlyError(loc, name);
-    SmallString<64> descriptiveKindStr;
-    {
-      if (!getIsolationRegionInfo().isDisconnected()) {
-        llvm::raw_svector_ostream os(descriptiveKindStr);
-        getIsolationRegionInfo().printForDiagnostics(getFunction(), os);
-        os << ' ';
-      }
-    }
 
-    SmallString<64> calleeIsolationStr;
-    {
-      llvm::raw_svector_ostream os(calleeIsolationStr);
-      SILIsolationInfo::printActorIsolationForDiagnostics(
-          getFunction(), crossing.getCalleeIsolation(), os);
-    }
-
-    SmallString<64> callerIsolationStr;
-    {
-      llvm::raw_svector_ostream os(callerIsolationStr);
-      SILIsolationInfo::printActorIsolationForDiagnostics(
-          getFunction(), crossing.getCallerIsolation(), os);
-    }
-
-    diagnoseNote(
-        loc, diag::regionbasedisolation_named_isolated_closure_yields_race,
-        descriptiveKindStr, name, calleeIsolationStr, callerIsolationStr)
+    auto descriptiveKindStr =
+        getIsolationRegionInfo().printForDiagnostics(getFunction());
+    auto calleeIsolationStr =
+        SILIsolationInfo::printActorIsolationForDiagnostics(
+            getFunction(), crossing.getCalleeIsolation());
+    auto callerIsolationStr =
+        SILIsolationInfo::printActorIsolationForDiagnostics(
+            getFunction(), crossing.getCallerIsolation());
+    bool isDisconnected = getIsolationRegionInfo().isDisconnected();
+    diagnoseNote(loc,
+                 diag::regionbasedisolation_named_isolated_closure_yields_race,
+                 isDisconnected, descriptiveKindStr, name, calleeIsolationStr,
+                 callerIsolationStr)
         .highlight(loc.getSourceRange());
   }
 
@@ -1483,11 +1411,8 @@ public:
         .highlight(loc.getSourceRange())
         .limitBehaviorIf(getBehaviorLimit());
 
-    SmallString<64> descriptiveKindStr;
-    {
-      llvm::raw_svector_ostream os(descriptiveKindStr);
-      getIsolationRegionInfo().printForDiagnostics(getFunction(), os);
-    }
+    auto descriptiveKindStr =
+        getIsolationRegionInfo().printForDiagnostics(getFunction());
 
     if (auto callee = getSendingCallee()) {
       diagnoseNote(
@@ -1505,12 +1430,8 @@ public:
   void emitClosureErrorWithCapturedActor(Operand *partialApplyOp,
                                          Operand *actualUse,
                                          SILArgument *fArg) {
-    SmallString<64> descriptiveKindStr;
-    {
-      llvm::raw_svector_ostream os(descriptiveKindStr);
-      getIsolationRegionInfo().getIsolationInfo().printForCodeDiagnostic(
-          getFunction(), os);
-    }
+    auto descriptiveKindStr =
+        getIsolationRegionInfo().printForCodeDiagnostic(getFunction());
 
     diagnoseError(partialApplyOp,
                   diag::regionbasedisolation_typed_tns_passed_sending_closure,
@@ -1518,12 +1439,8 @@ public:
         .limitBehaviorIf(getDiagnosticBehaviorLimitForOperands(
             actualUse->getFunction(), {actualUse}));
 
-    descriptiveKindStr.clear();
-    {
-      llvm::raw_svector_ostream os(descriptiveKindStr);
-      getIsolationRegionInfo().getIsolationInfo().printForDiagnostics(
-          getFunction(), os);
-    }
+    descriptiveKindStr =
+        getIsolationRegionInfo().printForDiagnostics(getFunction());
     diagnoseNote(actualUse, diag::regionbasedisolation_closure_captures_actor,
                  fArg->getDecl()->getName(), descriptiveKindStr);
   }
@@ -1538,12 +1455,8 @@ public:
   void emitSendingClosureParamDirectlyIsolated(Operand *partialApplyOp,
                                                Operand *actualUse,
                                                SILArgument *fArg) {
-    SmallString<64> descriptiveKindStr;
-    {
-      llvm::raw_svector_ostream os(descriptiveKindStr);
-      getIsolationRegionInfo().getIsolationInfo().printForCodeDiagnostic(
-          getFunction(), os);
-    }
+    auto descriptiveKindStr =
+        getIsolationRegionInfo().printForCodeDiagnostic(getFunction());
 
     diagnoseError(partialApplyOp,
                   diag::regionbasedisolation_typed_tns_passed_sending_closure,
@@ -1567,11 +1480,8 @@ public:
       return;
     }
 
-    descriptiveKindStr.clear();
-    {
-      llvm::raw_svector_ostream os(descriptiveKindStr);
-      getIsolationRegionInfo().printForDiagnostics(getFunction(), os);
-    }
+    descriptiveKindStr =
+        getIsolationRegionInfo().printForDiagnostics(getFunction());
 
     auto diag = diag::
         regionbasedisolation_typed_tns_passed_to_sending_closure_helper_have_value;
@@ -1588,11 +1498,8 @@ public:
       return;
     }
 
-    SmallString<64> descriptiveKindStr;
-    {
-      llvm::raw_svector_ostream os(descriptiveKindStr);
-      getIsolationRegionInfo()->printForCodeDiagnostic(getFunction(), os);
-    }
+    auto descriptiveKindStr =
+        getIsolationRegionInfo()->printForCodeDiagnostic(getFunction());
 
     auto emitMainError = [&] {
       auto behaviorLimit = getDiagnosticBehaviorLimitForOperands(
@@ -1624,11 +1531,8 @@ public:
       }
 
       emitMainError();
-      descriptiveKindStr.clear();
-      {
-        llvm::raw_svector_ostream os(descriptiveKindStr);
-        getIsolationRegionInfo().printForDiagnostics(getFunction(), os);
-      }
+      descriptiveKindStr =
+          getIsolationRegionInfo().printForDiagnostics(getFunction());
       auto diag = diag::
           regionbasedisolation_typed_tns_passed_to_sending_closure_helper_have_value_region;
       diagnoseNote(actualUseInfo->first, diag, descriptiveKindStr,
@@ -1669,11 +1573,8 @@ public:
            "Should never be disconnected?!");
     emitNamedOnlyError(loc, name);
 
-    SmallString<64> descriptiveKindStr;
-    {
-      llvm::raw_svector_ostream os(descriptiveKindStr);
-      getIsolationRegionInfo().printForDiagnostics(getFunction(), os);
-    }
+    auto descriptiveKindStr =
+        getIsolationRegionInfo().printForDiagnostics(getFunction());
 
     diagnoseNote(loc, diag::regionbasedisolation_named_send_nt_asynclet_capture,
                  name, descriptiveKindStr)
@@ -1683,34 +1584,22 @@ public:
   void emitNamedIsolation(SILLocation loc, Identifier name,
                           ApplyIsolationCrossing isolationCrossing) {
     emitNamedOnlyError(loc, name);
-    SmallString<64> descriptiveKindStr;
-    SmallString<64> descriptiveKindStrWithSpace;
-    {
-      if (!getIsolationRegionInfo().isDisconnected()) {
-        {
-          llvm::raw_svector_ostream os(descriptiveKindStr);
-          getIsolationRegionInfo().printForDiagnostics(getFunction(), os);
-        }
-        descriptiveKindStrWithSpace = descriptiveKindStr;
-        descriptiveKindStrWithSpace.push_back(' ');
-      }
-    }
 
-    SmallString<64> calleeIsolationStr;
-    {
-      llvm::raw_svector_ostream os(calleeIsolationStr);
-      SILIsolationInfo::printActorIsolationForDiagnostics(
-          getFunction(), isolationCrossing.getCalleeIsolation(), os);
-    }
+    auto descriptiveKindStr =
+        getIsolationRegionInfo().printForDiagnostics(getFunction());
+    auto calleeIsolationStr =
+        SILIsolationInfo::printActorIsolationForDiagnostics(
+            getFunction(), isolationCrossing.getCalleeIsolation());
+    bool isDisconnected = getIsolationRegionInfo().isDisconnected();
 
     if (auto callee = getSendingCallee()) {
       diagnoseNote(loc,
                    diag::regionbasedisolation_named_send_never_sendable_callee,
-                   name, descriptiveKindStrWithSpace, calleeIsolationStr,
+                   isDisconnected, name, descriptiveKindStr, calleeIsolationStr,
                    callee.value(), descriptiveKindStr);
     } else {
       diagnoseNote(loc, diag::regionbasedisolation_named_send_never_sendable,
-                   name, descriptiveKindStrWithSpace, calleeIsolationStr,
+                   isDisconnected, name, descriptiveKindStr, calleeIsolationStr,
                    descriptiveKindStr);
     }
   }
@@ -1718,34 +1607,21 @@ public:
   void emitNamedSendingNeverSendableToSendingParam(SILLocation loc,
                                                    Identifier varName) {
     emitNamedOnlyError(loc, varName);
-    SmallString<64> descriptiveKindStr;
-    {
-      if (!getIsolationRegionInfo().isDisconnected()) {
-        llvm::raw_svector_ostream os(descriptiveKindStr);
-        getIsolationRegionInfo().printForDiagnostics(getFunction(), os);
-        os << ' ';
-      }
-    }
+
+    auto descriptiveKindStr =
+        getIsolationRegionInfo().printForDiagnostics(getFunction());
+    bool isDisconnected = getIsolationRegionInfo().isDisconnected();
     auto diag = diag::regionbasedisolation_named_send_into_sending_param;
-    diagnoseNote(loc, diag, descriptiveKindStr, varName);
+    diagnoseNote(loc, diag, isDisconnected, descriptiveKindStr, varName);
   }
 
   void emitNamedSendingReturn(SILLocation loc, Identifier varName) {
     emitNamedOnlyError(loc, varName);
-    SmallString<64> descriptiveKindStr;
-    SmallString<64> descriptiveKindStrWithSpace;
-    {
-      if (!getIsolationRegionInfo().isDisconnected()) {
-        {
-          llvm::raw_svector_ostream os(descriptiveKindStr);
-          getIsolationRegionInfo().printForDiagnostics(getFunction(), os);
-        }
-        descriptiveKindStrWithSpace = descriptiveKindStr;
-        descriptiveKindStrWithSpace.push_back(' ');
-      }
-    }
+    auto descriptiveKindStr =
+        getIsolationRegionInfo().printForDiagnostics(getFunction());
+    bool isDisconnected = getIsolationRegionInfo().isDisconnected();
     auto diag = diag::regionbasedisolation_named_nosend_send_into_result;
-    diagnoseNote(loc, diag, descriptiveKindStrWithSpace, varName,
+    diagnoseNote(loc, diag, isDisconnected, descriptiveKindStr, varName,
                  descriptiveKindStr);
   }
 
@@ -2060,7 +1936,6 @@ bool SentNeverSendableDiagnosticInferrer::run() {
           return true;
 
         // See if we can infer a name from the value.
-        SmallString<64> resultingName;
         if (auto varName = inferNameHelper(op->get())) {
           diagnosticEmitter.emitNamedSendingNeverSendableToSendingParam(
               loc, *varName);
@@ -2101,7 +1976,6 @@ bool SentNeverSendableDiagnosticInferrer::run() {
     }
 
     // See if we can infer a name from the value.
-    SmallString<64> resultingName;
     if (auto name = inferNameHelper(op->get())) {
       diagnosticEmitter.emitNamedIsolation(loc, *name, *isolation);
       return true;
@@ -2149,7 +2023,6 @@ bool SentNeverSendableDiagnosticInferrer::run() {
                           }) &&
              "All result info must be the same... if that changes... update "
              "this code!");
-      SmallString<64> resultingName;
       if (auto name = inferNameHelper(op->get())) {
         diagnosticEmitter.emitNamedSendingReturn(loc, *name);
         return true;
@@ -2298,12 +2171,8 @@ void InOutSendingNotDisconnectedDiagnosticEmitter::emit() {
   }
 
   // Then emit the note with greater context.
-  SmallString<64> descriptiveKindStr;
-  {
-    llvm::raw_svector_ostream os(descriptiveKindStr);
-    actorIsolatedRegionInfo.printForDiagnostics(getFunction(), os);
-    os << ' ';
-  }
+  auto descriptiveKindStr =
+      actorIsolatedRegionInfo.printForDiagnostics(getFunction());
 
   diagnoseError(
       functionExitingInst,
@@ -2458,11 +2327,8 @@ static SILValue findOutParameter(SILValue v) {
 
 void AssignIsolatedIntoSendingResultDiagnosticEmitter::emit() {
   // Then emit the note with greater context.
-  SmallString<64> descriptiveKindStr;
-  {
-    llvm::raw_svector_ostream os(descriptiveKindStr);
-    isolatedValueIsolationRegionInfo.printForDiagnostics(getFunction(), os);
-  }
+  auto descriptiveKindStr =
+      isolatedValueIsolationRegionInfo.printForDiagnostics(getFunction());
 
   // Grab the var name if we can find it.
   if (auto varName = VariableNameInferrer::inferName(srcOperand->get())) {
@@ -2706,19 +2572,10 @@ void NonSendableIsolationCrossingResultDiagnosticEmitter::emit() {
   if (!isolationCrossing)
     return emitUnknownPatternError();
 
-  SmallString<64> calleeIsolationStr;
-  {
-    llvm::raw_svector_ostream os(calleeIsolationStr);
-    SILIsolationInfo::printActorIsolationForDiagnostics(
-        getFunction(), isolationCrossing->getCalleeIsolation(), os);
-  }
-
-  SmallString<64> callerIsolationStr;
-  {
-    llvm::raw_svector_ostream os(callerIsolationStr);
-    SILIsolationInfo::printActorIsolationForDiagnostics(
-        getFunction(), isolationCrossing->getCallerIsolation(), os);
-  }
+  auto calleeIsolationStr = SILIsolationInfo::printActorIsolationForDiagnostics(
+      getFunction(), isolationCrossing->getCalleeIsolation());
+  auto callerIsolationStr = SILIsolationInfo::printActorIsolationForDiagnostics(
+      getFunction(), isolationCrossing->getCallerIsolation());
 
   auto type = getType();
   if (getCalledDecl()) {
diff --git a/lib/SILOptimizer/Utils/SILIsolationInfo.cpp b/lib/SILOptimizer/Utils/SILIsolationInfo.cpp
index bde8f58e145..ac06873c368 100644
--- a/lib/SILOptimizer/Utils/SILIsolationInfo.cpp
+++ b/lib/SILOptimizer/Utils/SILIsolationInfo.cpp
@@ -1096,6 +1096,19 @@ void SILIsolationInfo::printOptions(llvm::raw_ostream &os) const {
   llvm::interleave(data, os, ", ");
 }
 
+StringRef SILIsolationInfo::printActorIsolationForDiagnostics(
+    SILFunction *fn, ActorIsolation iso, StringRef openingQuotationMark,
+    bool asNoun) {
+  SmallString<64> string;
+  {
+    llvm::raw_svector_ostream os(string);
+    printActorIsolationForDiagnostics(fn, iso, os, openingQuotationMark,
+                                      asNoun);
+  }
+
+  return fn->getASTContext().getIdentifier(string).str();
+}
+
 void SILIsolationInfo::printActorIsolationForDiagnostics(
     SILFunction *fn, ActorIsolation iso, llvm::raw_ostream &os,
     StringRef openingQuotationMark, bool asNoun) {
@@ -1250,6 +1263,16 @@ void SILIsolationInfo::Profile(llvm::FoldingSetNodeID &id) const {
   }
 }
 
+StringRef SILIsolationInfo::printForDiagnostics(SILFunction *fn) const {
+  SmallString<64> string;
+  {
+    llvm::raw_svector_ostream os(string);
+    printForDiagnostics(fn, os);
+  }
+
+  return fn->getASTContext().getIdentifier(string).str();
+}
+
 void SILIsolationInfo::printForDiagnostics(SILFunction *fn,
                                            llvm::raw_ostream &os) const {
   switch (Kind(*this)) {
@@ -1309,6 +1332,16 @@ void SILIsolationInfo::printForDiagnostics(SILFunction *fn,
   }
 }
 
+StringRef SILIsolationInfo::printForCodeDiagnostic(SILFunction *fn) const {
+  SmallString<64> string;
+  {
+    llvm::raw_svector_ostream os(string);
+    printForCodeDiagnostic(fn, os);
+  }
+
+  return fn->getASTContext().getIdentifier(string).str();
+}
+
 void SILIsolationInfo::printForCodeDiagnostic(SILFunction *fn,
                                               llvm::raw_ostream &os) const {
   switch (Kind(*this)) {