[clang] [clang] Move CWG2390 test into `cwg23xx.cpp` (PR #94206)

[Vlad Serebrennikov via cfe-commits]

https://github.com/Endilll created https://github.com/llvm/llvm-project/pull/94206

This patch refactors an existing test for [CWG2390](https://cplusplus.github.io/CWG/issues/2390.html) "Is the argument of `__has_cpp_attribute` macro-expanded?" to use `#error` instead of emitting a variable in IRGen and checking it via FileCheck. As a bonus, this makes it possible to move the test into `cwg23xx.cpp`.

>From 8b5382c62691ac4cb8bb0eeb0fe6a2b97b602b66 Mon Sep 17 00:00:00 2001
From: Vlad Serebrennikov <serebrennikov.vladislav at gmail.com>
Date: Mon, 3 Jun 2024 13:19:28 +0300
Subject: [PATCH] [clang] Move CWG2390 test into `cwg23xx.cpp`

---
 clang/test/CXX/drs/cwg2390.cpp | 47 ----------------------------------
 clang/test/CXX/drs/cwg23xx.cpp | 37 +++++++++++++++++++++++++-
 2 files changed, 36 insertions(+), 48 deletions(-)
 delete mode 100644 clang/test/CXX/drs/cwg2390.cpp

diff --git a/clang/test/CXX/drs/cwg2390.cpp b/clang/test/CXX/drs/cwg2390.cpp
deleted file mode 100644
index 41bbd0d1c5499..0000000000000
--- a/clang/test/CXX/drs/cwg2390.cpp
+++ /dev/null
@@ -1,47 +0,0 @@
-// RUN: %clang_cc1 -E -P %s -o - | FileCheck %s
-
-// cwg2390: 14
-
-namespace PR48462 {
-// Test that macro expansion of the builtin argument works.
-#define C clang
-#define F fallthrough
-#define CF clang::fallthrough
-
-#if __has_cpp_attribute(F)
-int has_fallthrough;
-#endif
-// CHECK: int has_fallthrough;
-
-#if __has_cpp_attribute(C::F)
-int has_clang_fallthrough_1;
-#endif
-// CHECK: int has_clang_fallthrough_1;
-
-#if __has_cpp_attribute(clang::F)
-int has_clang_fallthrough_2;
-#endif
-// CHECK: int has_clang_fallthrough_2;
-
-#if __has_cpp_attribute(C::fallthrough)
-int has_clang_fallthrough_3;
-#endif
-// CHECK: int has_clang_fallthrough_3;
-
-#if __has_cpp_attribute(CF)
-int has_clang_fallthrough_4;
-#endif
-// CHECK: int has_clang_fallthrough_4;
-
-#define FUNCLIKE1(x) clang::x
-#if __has_cpp_attribute(FUNCLIKE1(fallthrough))
-int funclike_1;
-#endif
-// CHECK: int funclike_1;
-
-#define FUNCLIKE2(x) _Clang::x
-#if __has_cpp_attribute(FUNCLIKE2(fallthrough))
-int funclike_2;
-#endif
-// CHECK: int funclike_2;
-} // namespace PR48462
diff --git a/clang/test/CXX/drs/cwg23xx.cpp b/clang/test/CXX/drs/cwg23xx.cpp
index ae5ec3b878f59..e4a1e90941dbf 100644
--- a/clang/test/CXX/drs/cwg23xx.cpp
+++ b/clang/test/CXX/drs/cwg23xx.cpp
@@ -317,7 +317,42 @@ namespace cwg2387 { // cwg2387: 9
 #endif
 }
 
-// cwg2390 is in cwg2390.cpp
+namespace cwg2390 { // cwg2390: 14
+// Test that macro expansion of the builtin argument works.
+#define C clang
+#define F fallthrough
+#define CF clang::fallthrough
+
+#if !__has_cpp_attribute(F)
+#error "doesn't have fallthrough"
+#endif
+
+#if !__has_cpp_attribute(C::F)
+#error "doesn't have clang::fallthrough 1"
+#endif
+
+#if !__has_cpp_attribute(clang::F)
+#error "doesn't have clang::fallthrough 2"
+#endif
+
+#if !__has_cpp_attribute(C::fallthrough)
+#error "doesn't have clang::fallthrough 3"
+#endif
+
+#if !__has_cpp_attribute(CF)
+#error "doesn't have clang::fallthrough 4"
+#endif
+
+#define FUNCLIKE1(x) clang::x
+#if !__has_cpp_attribute(FUNCLIKE1(fallthrough))
+#error "doesn't have clang::fallthrough through func-like macro 1"
+#endif
+
+#define FUNCLIKE2(x) _Clang::x
+#if !__has_cpp_attribute(FUNCLIKE2(fallthrough))
+#error "doesn't have clang::fallthrough through func-like macro 2"
+#endif
+} // namespace cwg2390
 
 namespace cwg2394 { // cwg2394: 15