--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gcc/testsuite/g++.dg/concepts/pr92804-1.C	Thu Feb 13 11:34:05 2020 +0900
@@ -0,0 +1,19 @@
+// { dg-do compile { target c++17 } }
+// { dg-options "-fconcepts" }
+
+template<typename T>
+concept foo = true;  // { dg-message "declared here" }
+
+template<typename T>
+void bar(T t)
+{
+  if constexpr (foo<T>::value)  // { dg-error "17:concept-id .foo<T>. in nested-name-specifier" }
+  // { dg-error "expected|value" "" { target c++17 } .-1 }
+  {
+  }
+}
+
+int main()
+{
+  bar(1);
+}