[clang-format] Correctly annotate C# nullable value type ? (#138631)

Fix #78666

Author: owenca

clang/lib/Format/TokenAnnotator.cpp

@@ -1720,22 +1720,12 @@ class AnnotatingParser {
         break;
       }
       if (Style.isCSharp()) {
-        // `Type?)`, `Type?>`, `Type? name;` and `Type? name =` can only be
+        // `Type?)`, `Type?>`, `Type? name;`, and `Type? name =` can only be
         // nullable types.
-
-        // `Type?)`, `Type?>`, `Type? name;`
-        if (Tok->Next &&
-            (Tok->Next->startsSequence(tok::question, tok::r_paren) ||
-             Tok->Next->startsSequence(tok::question, tok::greater) ||
-             Tok->Next->startsSequence(tok::question, tok::identifier,
-                                       tok::semi))) {
-          Tok->setType(TT_CSharpNullable);
-          break;
-        }
-
-        // `Type? name =`
-        if (Tok->Next && Tok->Next->is(tok::identifier) && Tok->Next->Next &&
-            Tok->Next->Next->is(tok::equal)) {
+        if (const auto *Next = Tok->getNextNonComment();
+            Next && (Next->isOneOf(tok::r_paren, tok::greater) ||
+                     Next->startsSequence(tok::identifier, tok::semi) ||
+                     Next->startsSequence(tok::identifier, tok::equal))) {
           Tok->setType(TT_CSharpNullable);
           break;
         }

clang/unittests/Format/TokenAnnotatorTest.cpp

@@ -3106,6 +3106,19 @@ TEST_F(TokenAnnotatorTest, CSharpNullableTypes) {
   ASSERT_EQ(Tokens.size(), 4u) << Tokens;
   EXPECT_TOKEN(Tokens[1], tok::question, TT_CSharpNullable);
 
+  Tokens = annotate("{\n"
+                    "  int? a;\n"
+                    "  if (b is int?)\n"
+                    "    f();\n"
+                    "  var foo = A<Foo?>();\n"
+                    "}",
+                    Style);
+  ASSERT_EQ(Tokens.size(), 29u) << Tokens;
+  EXPECT_TOKEN(Tokens[2], tok::question, TT_CSharpNullable);
+  EXPECT_TOKEN(Tokens[10], tok::question, TT_CSharpNullable);
+  EXPECT_TOKEN(Tokens[20], tok::less, TT_TemplateOpener);
+  EXPECT_TOKEN(Tokens[22], tok::question, TT_CSharpNullable);
+
   Tokens = annotate("cond? id : id2", Style);
   ASSERT_EQ(Tokens.size(), 6u) << Tokens;
   EXPECT_TOKEN(Tokens[1], tok::question, TT_ConditionalExpr);