--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/clang/test/AST/ast-dump-APValue-union.cpp	Tue Jun 08 06:07:14 2021 +0900
@@ -0,0 +1,63 @@
+// Test without serialization:
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -Wno-unused-value -std=gnu++17 \
+// RUN:            -ast-dump %s -ast-dump-filter Test \
+// RUN: | FileCheck --strict-whitespace --match-full-lines %s
+//
+// Test with serialization:
+// RUN: %clang_cc1 -triple x86_64-unknown-unknown -Wno-unused-value -std=gnu++17 -emit-pch -o %t %s
+// RUN: %clang_cc1 -x c++ -triple x86_64-unknown-unknown -Wno-unused-value -std=gnu++17 \
+// RUN:           -include-pch %t -ast-dump-all -ast-dump-filter Test /dev/null \
+// RUN: | sed -e "s/ <undeserialized declarations>//" -e "s/ imported//" \
+// RUN: | FileCheck --strict-whitespace --match-full-lines %s
+
+union U0 {
+  int i = 42;
+  float f;
+};
+
+union U1 {
+  union Uinner {
+    int i;
+    float f = 3.1415f;
+  } uinner;
+};
+
+union U2 {
+  union Uinner {
+    double d;
+    int arr[2] = {1, 2};
+  } uinner;
+};
+
+union U3 {
+  union Uinner {
+    double d = 3.1415;
+    int arr[2];
+  } uinner;
+  float f;
+};
+
+void Test() {
+  constexpr U0 u0{};
+  // CHECK:  | `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}} u0 'const U0' constexpr listinit
+  // CHECK-NEXT:  |   |-value: Union .i Int 42
+
+  constexpr U1 u1{};
+  // CHECK:  | `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}} u1 'const U1' constexpr listinit
+  // CHECK-NEXT:  |   |-value: Union .uinner Union .f Float 3.141500e+00
+
+  constexpr U2 u2{};
+  // CHECK:  | `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}} u2 'const U2' constexpr listinit
+  // CHECK-NEXT:  |   |-value: Union .uinner
+  // CHECK-NEXT:  |   | `-Union .arr
+  // CHECK-NEXT:  |   |   `-Array size=2
+  // CHECK-NEXT:  |   |     `-elements: Int 1, Int 2
+
+  constexpr U3 u3a = {.f = 3.1415};
+  // CHECK:  | `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}} u3a 'const U3' constexpr cinit
+  // CHECK-NEXT:  |   |-value: Union .f Float 3.141500e+00
+
+  constexpr U3 u3b = {.uinner = {}};
+  // CHECK:    `-VarDecl {{.*}} <col:{{.*}}, col:{{.*}}> col:{{.*}} u3b 'const U3' constexpr cinit
+  // CHECK-NEXT:      |-value: Union .uinner Union .d Float 3.141500e+00
+}