[clang-format] Correctly handle C# new modifier

[owenca]

Fix #75815

[llvmbot]

@llvm/pr-subscribers-clang-format

Author: Owen Pan (owenca)

Changes

Fix #75815

---

Full diff: https://github.com/llvm/llvm-project/pull/137430.diff

3 Files Affected:

• (modified) clang/lib/Format/UnwrappedLineParser.cpp (+7-1)
• (modified) clang/unittests/Format/FormatTestCSharp.cpp (+7)
• (modified) clang/unittests/Format/TokenAnnotatorTest.cpp (+11)

diff --git a/clang/lib/Format/UnwrappedLineParser.cpp b/clang/lib/Format/UnwrappedLineParser.cpp
index 9e86d9b19afb8..c7ad9962eb77f 100644
--- a/clang/lib/Format/UnwrappedLineParser.cpp
+++ b/clang/lib/Format/UnwrappedLineParser.cpp
@@ -2089,7 +2089,13 @@ void UnwrappedLineParser::parseStructuralElement(
       parseSquare();
       break;
     case tok::kw_new:
-      parseNew();
+      if (Style.isCSharp() &&
+          (Tokens->peekNextToken()->isAccessSpecifierKeyword() ||
+           (Previous && Previous->isAccessSpecifierKeyword()))) {
+        nextToken();
+      } else {
+        parseNew();
+      }
       break;
     case tok::kw_switch:
       if (Style.isJava())
diff --git a/clang/unittests/Format/FormatTestCSharp.cpp b/clang/unittests/Format/FormatTestCSharp.cpp
index dae362c37b52b..ea85ed6140dd0 100644
--- a/clang/unittests/Format/FormatTestCSharp.cpp
+++ b/clang/unittests/Format/FormatTestCSharp.cpp
@@ -689,6 +689,13 @@ TEST_F(FormatTestCSharp, CSharpNewOperator) {
                Style);
 }
 
+TEST_F(FormatTestCSharp, NewModifier) {
+  verifyFormat("public new class NestedC {\n"
+               "  public int x = 100;\n"
+               "}",
+               getLLVMStyle(FormatStyle::LK_CSharp));
+}
+
 TEST_F(FormatTestCSharp, CSharpLambdas) {
   FormatStyle GoogleStyle = getGoogleStyle(FormatStyle::LK_CSharp);
   FormatStyle MicrosoftStyle = getMicrosoftStyle(FormatStyle::LK_CSharp);
diff --git a/clang/unittests/Format/TokenAnnotatorTest.cpp b/clang/unittests/Format/TokenAnnotatorTest.cpp
index 8d4aeb7dec89a..08216dd971ac4 100644
--- a/clang/unittests/Format/TokenAnnotatorTest.cpp
+++ b/clang/unittests/Format/TokenAnnotatorTest.cpp
@@ -3109,6 +3109,17 @@ TEST_F(TokenAnnotatorTest, CSharpGenericTypeConstraint) {
   EXPECT_TOKEN(Tokens[18], tok::r_brace, TT_NamespaceRBrace);
 }
 
+TEST_F(TokenAnnotatorTest, CSharpNewModifier) {
+  auto Tokens = annotate("new public class NestedC {\n"
+                         "  public int x = 100;\n"
+                         "}",
+                         getGoogleStyle(FormatStyle::LK_CSharp));
+  ASSERT_EQ(Tokens.size(), 13u) << Tokens;
+  EXPECT_TOKEN(Tokens[3], tok::identifier, TT_ClassHeadName);
+  EXPECT_TOKEN(Tokens[4], tok::l_brace, TT_ClassLBrace);
+  EXPECT_TOKEN(Tokens[11], tok::r_brace, TT_ClassRBrace);
+}
+
 TEST_F(TokenAnnotatorTest, UnderstandsLabels) {
   auto Tokens = annotate("{ x: break; }");
   ASSERT_EQ(Tokens.size(), 7u) << Tokens;