[clang] [clang][NFC] Add test for CWG1898 "Use of “equivalent” in overload resolution" (PR #113439)

[Vlad Serebrennikov via cfe-commits]

https://github.com/Endilll created https://github.com/llvm/llvm-project/pull/113439

[CWG1898](https://cplusplus.github.io/CWG/issues/1898.html) Use of “equivalent” in overload resolution
====================

[P1787R6](https://wg21.link/p1787r6):
> CWG1898 is resolved by explicitly using the defined term parameter-type-list.

As for the wording, the first sentence [over.dcl]/1 where the word "equivalent" was used:
> Two function declarations of the same name refer to the same function if they are in the same scope and have equivalent parameter declarations ([over.load]).

was replaced with what is now known as "corresponding overloads", defined in [[basic.scope.scope]/4](https://eel.is/c++draft/basic.scope#scope-4). The definition is present in P1787R6, but it's hard to reference, because the "corresponding overloads" term was coined later.

>From 467c478cbc2400e1337e6dcc344a96e4a697341a Mon Sep 17 00:00:00 2001
From: Vlad Serebrennikov <serebrennikov.vladislav at gmail.com>
Date: Wed, 23 Oct 2024 12:59:36 +0300
Subject: [PATCH] =?UTF-8?q?[clang][NFC]=20Add=20test=20for=20CWG1898=20"Us?=
 =?UTF-8?q?e=20of=20=E2=80=9Cequivalent=E2=80=9D=20in=20overload=20resolut?=
 =?UTF-8?q?ion"?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 clang/test/CXX/drs/cwg18xx.cpp | 45 ++++++++++++++++++++++++++++++++++
 clang/www/cxx_dr_status.html   |  2 +-
 2 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/clang/test/CXX/drs/cwg18xx.cpp b/clang/test/CXX/drs/cwg18xx.cpp
index 7f0fb8cf589d48..3ec5c4d5c618b4 100644
--- a/clang/test/CXX/drs/cwg18xx.cpp
+++ b/clang/test/CXX/drs/cwg18xx.cpp
@@ -640,3 +640,48 @@ namespace H {
   struct S s;
 }
 }
+
+namespace cwg1898 { // cwg1898: 2.7
+void e(int) {} // #cwg1898-e-int
+void e(int) {}
+// expected-error at -1 {{redefinition of 'e'}}
+//   expected-note@#cwg1898-e-int {{previous definition is here}}
+void e(long) {}
+
+void f(int) {} // #cwg1898-f-int
+void f(const int) {}
+// expected-error at -1 {{redefinition of 'f'}}
+//   expected-note@#cwg1898-f-int {{previous definition is here}}
+
+void g(int) {} // #cwg1898-g-int
+void g(volatile int) {}
+// since-cxx20-warning at -1 {{volatile-qualified parameter type 'volatile int' is deprecated}}
+// expected-error at -2 {{redefinition of 'g'}}
+//   expected-note@#cwg1898-g-int {{previous definition is here}}
+
+void h(int *) {} // #cwg1898-h-int
+void h(int[]) {}
+// expected-error at -1 {{redefinition of 'h'}}
+//   expected-note@#cwg1898-h-int {{previous definition is here}}
+
+void i(int *) {} // #cwg1898-i-int
+void i(int[2]) {}
+// expected-error at -1 {{redefinition of 'i'}}
+//   expected-note@#cwg1898-i-int {{previous definition is here}}
+
+void j(void(*)()) {} // #cwg1898-j-int
+void j(void()) {}
+// expected-error at -1 {{redefinition of 'j'}}
+//   expected-note@#cwg1898-j-int {{previous definition is here}}
+
+struct A {
+  void k(int) {} // #cwg1898-k-int
+  void k(int) {}
+  // expected-error at -1 {{class member cannot be redeclared}}
+  //   expected-note@#cwg1898-k-int {{previous definition is here}}
+};
+
+struct B : A {
+  void k(int) {}
+};
+} // namespace cwg1898
diff --git a/clang/www/cxx_dr_status.html b/clang/www/cxx_dr_status.html
index 82ba9b370ba595..6640ed477a241e 100755
--- a/clang/www/cxx_dr_status.html
+++ b/clang/www/cxx_dr_status.html
@@ -11219,7 +11219,7 @@ <h2 id="cxxdr">C++ defect report implementation status</h2>
     <td><a href="https://cplusplus.github.io/CWG/issues/1898.html">1898</a></td>
     <td>CD6</td>
     <td>Use of “equivalent” in overload resolution</td>
-    <td class="unknown" align="center">Unknown</td>
+    <td class="full" align="center">Clang 2.7</td>
   </tr>
   <tr id="1899">
     <td><a href="https://cplusplus.github.io/CWG/issues/1899.html">1899</a></td>