https://github.com/swote-git created
https://github.com/llvm/llvm-project/pull/155570
Add test coverage to ensure comma operators remain properly rejected in `#if`
directives.
Per CWG 1436, comma is not among the permitted operators in preprocessor
conditional expressions. This test prevents regressions and clarifies the
intended behavior.
Addresses #132822
>From 36f751e7b92d8907bfe60f3c28748519578097c3 Mon Sep 17 00:00:00 2001
From: swote <kst7...@gmail.com>
Date: Wed, 27 Aug 2025 16:34:13 +0900
Subject: [PATCH] [clang][test] Add tests for comma operator rejection in
preprocessor expressions
Add test coverage for comma operator usage in #if preprocessor directives
to ensure it continues to be properly rejected across all C++ standard versions.
Per CWG 1436, comma operators are not among the permitted operators in
preprocessor conditional expressions.
Addresses #132822
---
clang/test/Preprocessor/cxx_oper_comma.cpp | 26 ++++++++++++++++++++++
1 file changed, 26 insertions(+)
create mode 100644 clang/test/Preprocessor/cxx_oper_comma.cpp
diff --git a/clang/test/Preprocessor/cxx_oper_comma.cpp
b/clang/test/Preprocessor/cxx_oper_comma.cpp
new file mode 100644
index 0000000000000..5589024ede01c
--- /dev/null
+++ b/clang/test/Preprocessor/cxx_oper_comma.cpp
@@ -0,0 +1,26 @@
+// RUN: %clang_cc1 -E -pedantic-errors %s -verify -std=c++98
+// RUN: %clang_cc1 -E -pedantic-errors %s -verify -std=c++11
+// RUN: %clang_cc1 -E -pedantic-errors %s -verify -std=c++14
+// RUN: %clang_cc1 -E -pedantic-errors %s -verify -std=c++17
+// RUN: %clang_cc1 -E -pedantic-errors %s -verify -std=c++20
+// RUN: %clang_cc1 -E -pedantic-errors %s -verify -std=c++23
+
+// Test 1: Top-level comma
+// expected-error@+1 {{expected end of line in preprocessor expression}}
+#if 1, 2
+#endif
+
+// Test 2: Comma in conditional expression
+// expected-error@+1 {{comma operator in operand of #if}}
+#if 1 ? 1, 0 : 3
+#endif
+
+// Test 3: Parenthesized comma
+// expected-error@+1 {{comma operator in operand of #if}}
+#if (1, 2)
+#endif
+
+// Test 4: Multiple commas
+// expected-error@+1 {{expected end of line in preprocessor expression}}
+#if 1, 2, 3
+#endif
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