Reland "Give NullabilityKind a printing operator<<"

This reverts commit 5326c9e480d70e16c2504cb5143524aff3ee2605.

The problem that caused the revert was downstream
(missing dep in user of clang).

2 files changed, 20 insertions, 22 deletions

diff --git a/clang/lib/Basic/Diagnostic.cpp b/clang/lib/Basic/Diagnostic.cpp
index 3474acbc..b2106b0 100644
--- a/clang/lib/Basic/Diagnostic.cpp
+++ b/clang/lib/Basic/Diagnostic.cpp
@@ -43,28 +43,12 @@ using namespace clang;
 
 const StreamingDiagnostic &clang::operator<<(const StreamingDiagnostic &DB,
                                              DiagNullabilityKind nullability) {
-  StringRef string;
-  switch (nullability.first) {
-  case NullabilityKind::NonNull:
-    string = nullability.second ? "'nonnull'" : "'_Nonnull'";
-    break;
-
-  case NullabilityKind::Nullable:
-    string = nullability.second ? "'nullable'" : "'_Nullable'";
-    break;
-
-  case NullabilityKind::Unspecified:
-    string = nullability.second ? "'null_unspecified'" : "'_Null_unspecified'";
-    break;
-
-  case NullabilityKind::NullableResult:
-    assert(!nullability.second &&
-           "_Nullable_result isn't supported as context-sensitive keyword");
-    string = "_Nullable_result";
-    break;
-  }
-
-  DB.AddString(string);
+  DB.AddString(
+      ("'" +
+       getNullabilitySpelling(nullability.first,
+                              /*isContextSensitive=*/nullability.second) +
+       "'")
+          .str());
   return DB;
 }
 
diff --git a/clang/lib/Basic/IdentifierTable.cpp b/clang/lib/Basic/IdentifierTable.cpp
index 97dc5cd..9be42c0 100644
--- a/clang/lib/Basic/IdentifierTable.cpp
+++ b/clang/lib/Basic/IdentifierTable.cpp
@@ -849,6 +849,20 @@ StringRef clang::getNullabilitySpelling(NullabilityKind kind,
   llvm_unreachable("Unknown nullability kind.");
 }
 
+llvm::raw_ostream &operator<<(llvm::raw_ostream &OS, NullabilityKind NK) {
+  switch (NK) {
+  case NullabilityKind::NonNull:
+    return OS << "NonNull";
+  case NullabilityKind::Nullable:
+    return OS << "Nullable";
+  case NullabilityKind::NullableResult:
+    return OS << "NullableResult";
+  case NullabilityKind::Unspecified:
+    return OS << "Unspecified";
+  }
+  llvm_unreachable("Unknown nullability kind.");
+}
+
 diag::kind
 IdentifierTable::getFutureCompatDiagKind(const IdentifierInfo &II,
                                          const LangOptions &LangOpts) {