diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 7819e39b97..cc17eba770 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2020-04-01  Tom Tromey  <tromey@adacore.com>
+
+	* gdb.rust/union.rs: New file.
+	* gdb.rust/union.exp: New file.
+	* gdb.rust/simple.rs (Union, Union2): Move to union.rs.
+	(main): Update.
+	* gdb.rust/simple.exp: Move union tests to union.exp.
+
 2020-04-01  Tom Tromey  <tromey@adacore.com>
 
 	* gdb.rust/simple.rs (main): Remove "y0".
diff --git a/gdb/testsuite/gdb.rust/simple.exp b/gdb/testsuite/gdb.rust/simple.exp
index b4fcf27426..92b3666386 100644
--- a/gdb/testsuite/gdb.rust/simple.exp
+++ b/gdb/testsuite/gdb.rust/simple.exp
@@ -335,17 +335,6 @@ gdb_test "print parametrized.next.val" \
 gdb_test "print parametrized" \
     " = simple::ParametrizedStruct<i32> \\{next: simple::ParametrizedEnum<\[a-z:\]*Box<simple::ParametrizedStruct<i32>>>::Val\\{val: $hex\\}, value: 0\\}"
 
-gdb_test "print u" " = simple::Union {f1: -1, f2: 255}"
-
-gdb_test_sequence "ptype/o Union" "" {
-    "/\\* offset    |  size \\*/  type = union simple::Union {"
-    "/\\*                 1 \\*/    f1: i8,"
-    "/\\*                 1 \\*/    f2: u8,"
-    ""
-    "                           /\\* total size \\(bytes\\):    1 \\*/"
-    "                         }"
-}
-
 gdb_test_sequence "ptype/o SimpleLayout" "" {
     "/\\* offset    |  size \\*/  type = struct simple::SimpleLayout {"
     "/\\*    0      |     2 \\*/    f1: u16,"
@@ -355,8 +344,6 @@ gdb_test_sequence "ptype/o SimpleLayout" "" {
     "                         }"
 }
 
-gdb_test "print u2" " = simple::Union2 {name: \\\[1\\\]}"
-
 gdb_test "print nonzero_offset" " = simple::EnumWithNonzeroOffset {a: core::option::Option<u8>::Some\\(1\\), b: core::option::Option<u8>::None}"
 
 # PR rust/23626 - this used to crash.  Note that the results are
diff --git a/gdb/testsuite/gdb.rust/simple.rs b/gdb/testsuite/gdb.rust/simple.rs
index f44e4affeb..78c3b21745 100644
--- a/gdb/testsuite/gdb.rust/simple.rs
+++ b/gdb/testsuite/gdb.rust/simple.rs
@@ -80,15 +80,6 @@ struct ParametrizedStruct<T> {
     value: T
 }
 
-union Union {
-    f1: i8,
-    f2: u8,
-}
-
-pub union Union2 {
-    pub name: [u8; 1],
-}
-
 struct StringAtOffset {
     pub field1: &'static str,
     pub field2: i32,
@@ -184,13 +175,10 @@ fn main () {
         value: 0,
     };
 
-    let u = Union { f2: 255 };
     let simplelayout = SimpleLayout { f1: 8, f2: 9 };
 
     let empty_enum_value: EmptyEnum;
 
-    let u2 = Union2 { name: [1] };
-
     let nonzero_offset = EnumWithNonzeroOffset { a: Some(1), b: None };
 
     println!("{}, {}", x.0, x.1);        // set breakpoint here
diff --git a/gdb/testsuite/gdb.rust/union.exp b/gdb/testsuite/gdb.rust/union.exp
new file mode 100644
index 0000000000..c7864a2fc9
--- /dev/null
+++ b/gdb/testsuite/gdb.rust/union.exp
@@ -0,0 +1,45 @@
+# Copyright (C) 2020 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Test of "union" for Rust.
+
+load_lib rust-support.exp
+if {[skip_rust_tests]} {
+    continue
+}
+
+standard_testfile .rs
+if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug rust}]} {
+    return -1
+}
+
+set line [gdb_get_line_number "set breakpoint here"]
+if {![runto ${srcfile}:$line]} {
+    untested "could not run to breakpoint"
+    return -1
+}
+
+gdb_test "print u" " = union::Union {f1: -1, f2: 255}"
+
+gdb_test_sequence "ptype/o Union" "" {
+    "/\\* offset    |  size \\*/  type = union union::Union {"
+    "/\\*                 1 \\*/    f1: i8,"
+    "/\\*                 1 \\*/    f2: u8,"
+    ""
+    "                           /\\* total size \\(bytes\\):    1 \\*/"
+    "                         }"
+}
+
+gdb_test "print u2" " = union::Union2 {name: \\\[1\\\]}"
diff --git a/gdb/testsuite/gdb.rust/union.rs b/gdb/testsuite/gdb.rust/union.rs
new file mode 100644
index 0000000000..ef3069641b
--- /dev/null
+++ b/gdb/testsuite/gdb.rust/union.rs
@@ -0,0 +1,35 @@
+// Copyright (C) 2020 Free Software Foundation, Inc.
+
+// This program is free software; you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation; either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#![allow(dead_code)]
+#![allow(unused_variables)]
+#![allow(unused_assignments)]
+
+
+union Union {
+    f1: i8,
+    f2: u8,
+}
+
+pub union Union2 {
+    pub name: [u8; 1],
+}
+
+fn main() {
+    let u = Union { f2: 255 };
+    let u2 = Union2 { name: [1] };
+
+    println!("Hi");        // set breakpoint here
+}