Missing index check for null array.

src/bounds.c

@@ -179,9 +179,6 @@ static tree_t bounds_check_call_args(tree_t t)
 static bool index_in_range(tree_t index, int64_t low, int64_t high,
                            int64_t *value)
 {
-   if (low > high)
-      return true;   // Null range allows any index
-
    int64_t folded;
    if (folded_int(index, &folded)) {
       *value = folded;
@@ -195,7 +192,7 @@ static bool bounds_check_index(tree_t index, type_t type, range_kind_t kind,
                                const char *what, int64_t low, int64_t high)
 {
    int64_t folded;
-   if (!index_in_range(index, low, high, &folded)) {
+   if (!index_in_range(index, low, high, &folded) && low <= high) {
       LOCAL_TEXT_BUF tb = tb_new();
       tb_cat(tb, what);
       tb_printf(tb, " index ");

src/vcode.c

@@ -5537,11 +5537,6 @@ static void emit_bounds_check(vcode_op_t kind, vcode_reg_t reg,
                               vcode_reg_t dir, vcode_reg_t locus,
                               vcode_reg_t hint)
 {
-   if (reg == left || reg == right) {
-      emit_comment("Elided trivial bounds check for r%d", reg);
-      return;
-   }
-
    VCODE_FOR_EACH_MATCHING_OP(other, kind) {
       if (other->args.items[0] == reg && other->args.items[1] == left
           && other->args.items[2] == right && other->args.items[3] == dir)
@@ -5555,18 +5550,14 @@ static void emit_bounds_check(vcode_op_t kind, vcode_reg_t reg,
          const bool is_null = (dconst == RANGE_TO && lconst > rconst)
             || (dconst == RANGE_DOWNTO && rconst > lconst);
 
-         if (is_null) {
-            emit_comment("Elided bounds check for null range");
-            return;
-         }
-
          vtype_t *bounds = vcode_type_data(vcode_reg_bounds(reg));
 
          const bool ok_static =
             (dconst == RANGE_TO
              && bounds->low >= lconst && bounds->high <= rconst)
             || (dconst == RANGE_DOWNTO
-                && bounds->low >= rconst && bounds->high <= lconst);
+                && bounds->low >= rconst && bounds->high <= lconst)
+            || (!is_null && (reg == left || reg == right));
 
          if (ok_static) {
             emit_comment("Elided bounds check for r%d", reg);

test/bounds/issue734.vhd

@@ -0,0 +1,15 @@
+entity issue734 is
+end entity ;
+
+architecture arch of issue734 is
+    signal val : bit_vector(0 downto 1) ;
+begin
+
+    tb : process
+    begin
+        val(0) <= '0' ;                 -- Error
+        val(1 downto 0) <= "00";        -- Error
+        wait ;
+    end process ;
+
+end architecture ;

test/regress/gold/issue734.txt

@@ -0,0 +1 @@
+1ns+0: index 0 outside of INTEGER range 0 downto 1

test/regress/issue734.vhd

@@ -0,0 +1,16 @@
+entity issue734 is
+end entity ;
+
+architecture arch of issue734 is
+    signal val : bit_vector(0 downto 1) ;
+begin
+
+    tb : process
+        variable n : integer := 0;
+    begin
+        wait for 1 ns;
+        val(n) <= '0' ;                 -- Error
+        wait ;
+    end process ;
+
+end architecture ;

test/regress/testlist.txt

@@ -793,7 +793,7 @@ view5           normal,2019
 issue705        normal,2008
 array17         normal,2008
 stdenv5         normal,2019
-assert7         fail,2008
+assert7         fail,gold,2008
 vhpi7           normal,2008,vhpi
 vhpi8           normal,2008,vhpi
 issue704        wave,no-collapse
@@ -814,3 +814,4 @@ protected10     normal,2019
 reflect1        normal,2019
 signal32        normal,2019
 reflect2        normal,2019
+issue734        fail,gold,2008

test/test_bounds.c

@@ -612,6 +612,25 @@ START_TEST(test_issue617)
 }
 END_TEST
 
+START_TEST(test_issue734)
+{
+   input_from_file(TESTDIR "/bounds/issue734.vhd");
+
+   const error_t expect[] = {
+      { 10, "array VAL index 0 outside of NATURAL range 0 downto 1" },
+      { 11, "VAL slice left index 1 outside of NATURAL range 0 downto 1" },
+      { -1, NULL }
+   };
+   expect_errors(expect);
+
+   tree_t a = parse_check_and_simplify(T_ENTITY, T_ARCH);
+   fail_unless(error_count() == 0);
+
+   bounds_check(a);
+   check_expected_errors();
+}
+END_TEST
+
 Suite *get_bounds_tests(void)
 {
    Suite *s = suite_create("bounds");
@@ -642,6 +661,7 @@ Suite *get_bounds_tests(void)
    tcase_add_test(tc_core, test_driver1);
    tcase_add_test(tc_core, test_nullrange);
    tcase_add_test(tc_core, test_issue617);
+   tcase_add_test(tc_core, test_issue734);
    suite_add_tcase(s, tc_core);
 
    return s;

test/test_lower.c

@@ -2254,6 +2254,8 @@ START_TEST(test_issue149)
       { VCODE_OP_DEBUG_LOCUS },
       { VCODE_OP_TRAP_SUB },
       { VCODE_OP_CONST, .value = 0 },
+      { VCODE_OP_DEBUG_LOCUS },
+      { VCODE_OP_RANGE_CHECK },
       { VCODE_OP_CONST, .value = -1 },
       { VCODE_OP_DEBUG_LOCUS },
       { VCODE_OP_DEBUG_LOCUS },