1 files changed, 28 insertions, 0 deletions
diff --git a/gcc/testsuite/g++.dg/cpp2a/is-constant-evaluated15.C b/gcc/testsuite/g++.dg/cpp2a/is-constant-evaluated15.C
new file mode 100644
index 00000000000..50a3cac6e07
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp2a/is-constant-evaluated15.C
@@ -0,0 +1,28 @@
+// PR c++/114580
+// { dg-do compile { target c++17 } }
+// { dg-options "-Wtautological-compare" }
+
+namespace std {
+  constexpr inline bool
+  is_constant_evaluated () noexcept
+  {
+#if __cpp_if_consteval >= 202106L
+    if consteval { return true; } else { return false; }
+#else
+    return __builtin_is_constant_evaluated ();
+#endif
+  }
+}
+
+template <typename T>
+void foo ()
+{
+  if constexpr ((T) std::is_constant_evaluated ())	// { dg-warning "'std::is_constant_evaluated' always evaluates to true in 'if constexpr'" }
+    ;							// { dg-bogus "'std::is_constant_evaluated' always evaluates to false in a non-'constexpr' function" }
+}
+
+void
+bar ()
+{
+  foo <bool> ();
+}