make BoundsSafety std::optional, add test w/o optional level field

Author: hnrklssn

clang/lib/APINotes/APINotesYAMLCompiler.cpp

@@ -214,10 +214,10 @@ struct Param {
   std::optional<bool> Lifetimebound = false;
   std::optional<NullabilityKind> Nullability;
   std::optional<RetainCountConventionKind> RetainCountConvention;
-  StringRef Type;
   /* TO_UPSTREAM(BoundsSafety) ON */
-  BoundsSafety BoundsSafety;
+  std::optional<BoundsSafety> BoundsSafety;
   /* TO_UPSTREAM(BoundsSafety) OFF */
+  StringRef Type;
 };
 
 typedef std::vector<Param> ParamsSeq;
@@ -907,9 +907,11 @@ class YAMLConverter {
       PI.setRetainCountConvention(P.RetainCountConvention);
       BoundsSafetyInfo BSI;
       /* TO_UPSTREAM(BoundsSafety) ON */
-      BSI.setKindAudited(P.BoundsSafety.Kind);
-      BSI.setLevelAudited(P.BoundsSafety.Level);
-      BSI.ExternalBounds = P.BoundsSafety.BoundsExpr.str();
+      if (P.BoundsSafety) {
+        BSI.setKindAudited(P.BoundsSafety->Kind);
+        BSI.setLevelAudited(P.BoundsSafety->Level);
+        BSI.ExternalBounds = P.BoundsSafety->BoundsExpr.str();
+      }
       PI.BoundsSafety = BSI;
       /* TO_UPSTREAM(BoundsSafety) OFF */
       if (static_cast<int>(OutInfo.Params.size()) <= P.Position)

clang/test/APINotes/Inputs/Headers/BoundsUnsafe.apinotes

@@ -72,6 +72,12 @@ Functions:
             Kind: counted_by
             Level: 0
             BoundedBy: len
+  - Name:              asdf_counted_default_level
+    Parameters:
+      - Position:      0
+        BoundsSafety:
+            Kind: counted_by
+            BoundedBy: len
   - Name:              asdf_nterm
     Parameters:
       - Position:      0

clang/test/APINotes/Inputs/Headers/BoundsUnsafe.h

@@ -9,5 +9,6 @@ void asdf_counted_out(int ** buf, int * len);
 void asdf_counted_const(int * buf);
 void asdf_counted_nullable(int len, int * _Nullable buf);
 void asdf_counted_noescape(int * buf, int len);
+void asdf_counted_default_level(int * buf, int len);
 
 void asdf_nterm(char * buf);

clang/test/APINotes/boundssafety.c

@@ -35,6 +35,9 @@
 // CHECK: buf 'int * __counted_by(len)':'int *'
 // CHECK-NEXT: NoEscapeAttr
 
+// CHECK: asdf_counted_default_level 'void (int * __counted_by(len), int)'
+// CHECK: buf 'int * __counted_by(len)':'int *'
+
 // CHECK: asdf_nterm 'void (int * __terminated_by(0))'
 // CHECK: buf 'int * __terminated_by(0)':'int *'