testsuite/synth: add more tests for subtraction in std_logic_unsigned

1 files changed, 13 insertions, 0 deletions

diff --git a/testsuite/synth/issue1951/sub02.vhdl b/testsuite/synth/issue1951/sub02.vhdl
new file mode 100644
index 000000000..ebe9be1f9
--- /dev/null
+++ b/testsuite/synth/issue1951/sub02.vhdl
@@ -0,0 +1,13 @@
+library ieee;
+use ieee.std_logic_1164.all;
+use ieee.std_logic_unsigned.all;
+
+entity sub02 is
+  port (i : std_logic_vector (3 downto 0);
+        o : out std_logic_vector (3 downto 0));
+end entity;
+
+architecture arch of sub02 is
+begin
+  o <= i - (-7);
+end arch;