[clang] [clang] Add tests for CWG1800-1804 (PR #77509)

[via cfe-commits]

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@@ -1,16 +1,169 @@
-// RUN: %clang_cc1 -std=c++98 -triple x86_64-unknown-unknown %s -verify=expected,cxx98 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-unknown %s -verify=expected,cxx11-17,since-cxx11 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++14 -triple x86_64-unknown-unknown %s -verify=expected,cxx11-17,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++17 -triple x86_64-unknown-unknown %s -verify=expected,cxx11-17,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-unknown %s -verify=expected,since-cxx20,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++23 -triple x86_64-unknown-unknown %s -verify=expected,since-cxx20,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
-// RUN: %clang_cc1 -std=c++2c -triple x86_64-unknown-unknown %s -verify=expected,since-cxx20,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++98 -triple x86_64-unknown-unknown %s -verify=expected,cxx98-14,cxx98 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-unknown %s -verify=expected,cxx98-14,cxx11-17,since-cxx11 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++14 -triple x86_64-unknown-unknown %s -verify=expected,cxx98-14,cxx11-17,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++17 -triple x86_64-unknown-unknown %s -verify=expected,since-cxx17,cxx11-17,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-unknown %s -verify=expected,since-cxx17,since-cxx20,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++23 -triple x86_64-unknown-unknown %s -verify=expected,since-cxx17,since-cxx20,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
+// RUN: %clang_cc1 -std=c++2c -triple x86_64-unknown-unknown %s -verify=expected,since-cxx17,since-cxx20,since-cxx11,since-cxx14 -fexceptions -Wno-deprecated-builtins -fcxx-exceptions -pedantic-errors
 
 #if __cplusplus == 199711L
 #define static_assert(...) __extension__ _Static_assert(__VA_ARGS__)
 // cxx98-error at -1 {{variadic macros are a C99 feature}}
 #endif
 
+namespace dr1800 { // dr1800: 2.9
+struct A { union { int n; }; };
+static_assert(__is_same(__decltype(&A::n), int A::*), "");
+} // namespace dr1800
+
+namespace dr1801 { // dr1801: 2.8
+static union {
+  int i;
+};
+
+template <int &> struct S {}; // #dr1801-S
+S<i> V; // #dr1801-S-i
+// cxx98-14-error at -1 {{non-type template argument does not refer to any declaration}}
+//   cxx98-14-note@#dr1801-S {{template parameter is declared here}}
+// since-cxx17-error@#dr1801-S-i {{non-type template argument refers to subobject '.i'}}
+}
+
+namespace dr1802 { // dr1802: 3.1
+#if __cplusplus >= 201103L
+// Using a Wikipedia example of surrogate pair:
+// https://en.wikipedia.org/wiki/UTF-16#Examples
+constexpr char16_t a[3] = u"𐐷";
+static_assert(a[0] == 0xD801, "");
+static_assert(a[1] == 0xDC37, "");
+static_assert(a[2] == 0x0, "");
+#endif
+} // namespace dr1802
+
+namespace dr1803 { // dr1803: 2.9
+#if __cplusplus >= 201103L
----------------
cor3ntin wrote:

@erichkeane I think it looks reasonable but I would like a second pair of eyes
https://cplusplus.github.io/CWG/issues/1804.html

https://github.com/llvm/llvm-project/pull/77509