--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang/test/AST/ast-dump-concepts.cpp	Tue Jun 08 06:07:14 2021 +0900
@@ -0,0 +1,51 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -std=c++2a -ast-dump -ast-dump-filter Foo %s | FileCheck -strict-whitespace %s
+
+// Test with serialization:
+// RUN: %clang_cc1 -std=c++20 -triple x86_64-unknown-unknown -emit-pch -o %t %s
+// RUN: %clang_cc1 -x c++ -std=c++20 -triple x86_64-unknown-unknown -include-pch %t \
+// RUN: -ast-dump-all -ast-dump-filter Foo /dev/null \
+// RUN: | FileCheck --strict-whitespace %s
+
+template <typename T>
+concept unary_concept = true;
+
+template <typename T, typename U>
+concept binary_concept = true;
+
+template <typename... Ts>
+concept variadic_concept = true;
+
+template <typename T>
+struct Foo {
+  // CHECK:      TemplateTypeParmDecl {{.*}} referenced Concept {{.*}} 'binary_concept'
+  // CHECK-NEXT: `-ConceptSpecializationExpr {{.*}} <col:13, col:31> 'bool' Concept {{.*}} 'binary_concept'
+  // CHECK-NEXT:   |-TemplateArgument {{.*}} type 'R'
+  // CHECK-NEXT:   | `-TemplateTypeParmType {{.*}} 'R'
+  // CHECK-NEXT:   |   `-TemplateTypeParm {{.*}} 'R'
+  // CHECK-NEXT:   `-TemplateArgument {{.*}} type 'int'
+  // CHECK-NEXT:     `-BuiltinType {{.*}} 'int'
+  template <binary_concept<int> R>
+  Foo(R);
+
+  // CHECK:      TemplateTypeParmDecl {{.*}} referenced Concept {{.*}} 'unary_concept'
+  // CHECK-NEXT: `-ConceptSpecializationExpr {{.*}} <col:13> 'bool'
+  template <unary_concept R>
+  Foo(R);
+
+  // CHECK:      FunctionTemplateDecl {{.*}} <line:[[@LINE+1]]:3, line:[[@LINE+2]]:39> {{.*}} Foo<T>
+  template <typename R>
+  Foo(R, int) requires unary_concept<R>;
+
+  // CHECK:      FunctionTemplateDecl {{.*}} <line:[[@LINE+1]]:3, line:[[@LINE+3]]:3> {{.*}} Foo<T>
+  template <typename R>
+  Foo(R, char) requires unary_concept<R> {
+  }
+
+  // CHECK: CXXFoldExpr {{.*}} <col:13, col:29>
+  template <variadic_concept... Ts>
+  Foo();
+
+  // CHECK: CXXFoldExpr {{.*}} <col:13, col:34>
+  template <variadic_concept<int>... Ts>
+  Foo();
+};