[rbi] Use interned StringRefs for diagnostics instead of SmallString<64>.

This makes the code easier to write and also prevents any lifetime issues from a
diagnostic outliving the SmallString due to diagnostic transactions.

(cherry picked from commit 010fa39)

Author: gottesmm

include/swift/AST/DiagnosticsSIL.def

@@ -990,11 +990,11 @@ 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,
@@ -1010,8 +1010,8 @@ 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",
@@ -1024,19 +1024,19 @@ 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",
@@ -1098,10 +1098,10 @@ 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))
 
 //===

include/swift/AST/Identifier.h

@@ -230,7 +230,7 @@ class Identifier {
 private:
   bool isOperatorSlow() const;
 };
-  
+
 class DeclName;
 class DeclNameRef;
 class ObjCSelector;

include/swift/SILOptimizer/Utils/SILIsolationInfo.h

@@ -380,8 +380,16 @@ class SILIsolationInfo {
   /// 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';
@@ -579,6 +587,12 @@ class SILIsolationInfo {
       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:
@@ -648,6 +662,10 @@ class SILDynamicMergedIsolationInfo {
     innerInfo.printForDiagnostics(fn, os);
   }
 
+  StringRef printForDiagnostics(SILFunction *fn) const {
+    return innerInfo.printForDiagnostics(fn);
+  }
+
   SWIFT_DEBUG_DUMPER(dumpForDiagnostics(SILFunction *fn)) {
     innerInfo.dumpForDiagnostics(fn);
   }
@@ -656,6 +674,10 @@ class SILDynamicMergedIsolationInfo {
     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);
   }