Fix a regression in aggregate type checking. Fixes xxx

NEWS.md

@@ -3,6 +3,8 @@
   (from @NikLeberg) (#1091).
 - Fixed a crash when a constant record aggregate has a null array
   element (#1137).
+- Fixed a regression that caused some array aggregates to be incorrectly
+  reported as ambiguous (#1138).
 
 ## Version 1.15.0 - 2025-01-11
 - `--load` is now a global option and should be placed before the `-r`

src/names.c

@@ -4495,16 +4495,13 @@ static type_t solve_array_aggregate(nametab_t *tab, tree_t agg, type_t type)
    type_set_push(tab, &ts);
 
    type_t t0, t1 = NULL;
-   bool composite_elem = false;
    const int ndims = dimension_of(type);
    if (ndims == 1) {
       type_t elem = type_elem(type);
       type_set_add(tab, (t0 = elem), NULL);
 
-      if (standard() >= STD_08) {
+      if (standard() >= STD_08)
          t1 = type_base_recur(type);
-         composite_elem = type_is_composite(elem);
-      }
    }
    else
       t0 = array_aggregate_type(type, 1);
@@ -4563,30 +4560,37 @@ static type_t solve_array_aggregate(nametab_t *tab, tree_t agg, type_t type)
          break;
       }
 
-      bool allow_slice = t1 != NULL && (kind == A_POS || kind == A_RANGE);
-
-      // This seems incorrect according to the 2008 LRM but without it
-      // many previously legal nested aggregates are ambiguous
-      tree_t value = tree_value(a);
-      if (composite_elem && tree_kind(value) == T_AGGREGATE)
-         allow_slice = false;
-
       // Hack to avoid pushing/popping type set on each iteration
       ATRIM(tab->top_type_set->members, 0);
       type_set_add(tab, t0, NULL);
-      if (allow_slice)
-         type_set_add(tab, t1, NULL);
 
-      type_t etype = _solve_types(tab, value);
+      tree_t value = tree_value(a);
 
-      if (allow_slice && type_eq(etype, t1)) {
-         // VHDL-2008 slice in aggregate
-         switch (kind) {
-         case A_RANGE: tree_set_subkind(a, A_SLICE); break;
-         case A_POS: tree_set_subkind(a, A_CONCAT); break;
-         default: break;
+      if (t1 != NULL && (kind == A_POS || kind == A_RANGE)) {
+         // In the 2008 LRM the value may have the same type as the
+         // aggregate it which case it behaves as a concatentation.
+         // However we only choose this interpretation if the aggregate
+         // would be illegal without it, as otherwise many previously
+         // legal nested aggregates are ambiguous.
+         type_t etype;
+         if (is_unambiguous(value))
+            etype = _solve_types(tab, value);
+         else if ((etype = try_solve_type(tab, value)) == NULL) {
+            type_set_add(tab, t1, NULL);
+            etype = _solve_types(tab, value);
+         }
+
+         if (type_eq(etype, t1)) {
+            // VHDL-2008 slice in aggregate
+            switch (kind) {
+            case A_RANGE: tree_set_subkind(a, A_SLICE); break;
+            case A_POS: tree_set_subkind(a, A_CONCAT); break;
+            default: should_not_reach_here();
+            }
          }
       }
+      else
+         _solve_types(tab, value);
    }
 
    type_set_pop(tab, &ts);

test/parse/issue1138.vhd

@@ -0,0 +1,17 @@
+entity test is
+end entity test;
+
+architecture rtl of test is
+
+    subtype slv64_type is bit_vector(0 to 63);
+    type    slv64_array_type is array (natural range <>) of slv64_type;
+
+    constant zeroes : bit_vector(0 to 31)  := x"00000000";
+    constant more_zeroes : bit_vector(0 to 31) := x"00000000";
+
+    -- doesn't work in nvc 1.15.0, works in nvc 1.14.2
+    -- error: ambiguous use of operator "&"
+    constant test_constant : slv64_array_type := (zeroes & more_zeroes, zeroes & more_zeroes);
+
+begin
+end architecture rtl;

test/test_parse.c

@@ -7204,6 +7204,20 @@ START_TEST(test_issue1129)
 }
 END_TEST
 
+START_TEST(test_issue1138)
+{
+   set_standard(STD_08);
+
+   input_from_file(TESTDIR "/parse/issue1138.vhd");
+
+   parse_and_check(T_ENTITY, T_ARCH);
+
+   fail_unless(parse() == NULL);
+
+   fail_if_errors();
+}
+END_TEST
+
 Suite *get_parse_tests(void)
 {
    Suite *s = suite_create("parse");
@@ -7382,6 +7396,7 @@ Suite *get_parse_tests(void)
    tcase_add_test(tc_core, test_aggregate2);
    tcase_add_test(tc_core, test_issue1124);
    tcase_add_test(tc_core, test_issue1129);
+   tcase_add_test(tc_core, test_issue1138);
    suite_add_tcase(s, tc_core);
 
    return s;