Add tests for comma operator rejection in preprocessor expressions

[swote-git]

This commit adds test cases to verify correct rejection of comma operators in
preprocessor expressions, in accordance with C++ standard CWG issue 1436. The
standard explicitly states that comma operators are not permitted in
preprocessor expressions (15.2 [cpp.cond] paragraph 12).

Relates to GitHub issue #132822 .

[github-actions]

Thank you for submitting a Pull Request (PR) to the LLVM Project!

This PR will be automatically labeled and the relevant teams will be notified.

If you wish to, you can add reviewers by using the "Reviewers" section on this page.

If this is not working for you, it is probably because you do not have write permissions for the repository. In which case you can instead tag reviewers by name in a comment by using @ followed by their GitHub username.

If you have received no comments on your PR for a week, you can request a review by "ping"ing the PR by adding a comment “Ping”. The common courtesy "ping" rate is once a week. Please remember that you are asking for valuable time from other developers.

If you have further questions, they may be answered by the LLVM GitHub User Guide.

You can also ask questions in a comment on this PR, on the LLVM Discord or on the forums.

[llvmbot]

@llvm/pr-subscribers-clang

Author: NohHyeon Kwon (swote-git)

Changes

This commit adds test cases to verify correct rejection of comma operators in
preprocessor expressions, in accordance with C++ standard CWG issue 1436. The
standard explicitly states that comma operators are not permitted in
preprocessor expressions (15.2 [cpp.cond] paragraph 12).

Relates to GitHub issue #132822 .

---

Full diff: https://github.com/llvm/llvm-project/pull/139209.diff

1 Files Affected:

• (added) clang/test/Preprocessor/cxx_oper_comma.cpp (+26)

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