From e4864771edba19ed2d86c516af76f149a396ac84 Mon Sep 17 00:00:00 2001
From: Nick Gasson <nick@nickg.me.uk>
Date: Wed, 17 Feb 2016 20:41:27 +0000
Subject: [PATCH] Earlier bounds checking during elaboration. Fixes #251

---
 src/elab.c             | 11 ++++++++++-
 test/elab/issue251.vhd | 34 ++++++++++++++++++++++++++++++++++
 test/test_elab.c       | 16 ++++++++++++++++
 3 files changed, 60 insertions(+), 1 deletion(-)
 create mode 100644 test/elab/issue251.vhd

diff --git a/src/elab.c b/src/elab.c
index bd93b424..0b1cf4e0 100644
--- a/src/elab.c
+++ b/src/elab.c
@@ -603,7 +603,15 @@ static netid_t elab_get_net(tree_t expr, int n)
 {
    switch (tree_kind(expr)) {
    case T_REF:
-      return tree_net(tree_ref(expr), n);
+      {
+         tree_t decl = tree_ref(expr);
+         if (n < 0 || n >= tree_nets(decl)) {
+            assert(bounds_errors() > 0);   // Should have already caught this
+            return NETID_INVALID;
+         }
+         else
+            return tree_net(tree_ref(expr), n);
+      }
 
    case T_ARRAY_REF:
       {
@@ -1423,6 +1431,7 @@ static void elab_entity_arch(tree_t t, tree_t arch, const elab_ctx_t *ctx)
 
    elab_funcs(arch, t, ctx);
    simplify(arch);
+   bounds_check(arch);
 
    elab_ctx_t new_ctx = {
       .out      = ctx->out,
diff --git a/test/elab/issue251.vhd b/test/elab/issue251.vhd
new file mode 100644
index 00000000..e23e4b66
--- /dev/null
+++ b/test/elab/issue251.vhd
@@ -0,0 +1,34 @@
+entity sub is
+    port (
+        x : in bit_vector(3 downto 0);
+        y : out bit );
+end entity;
+
+architecture test of sub is
+begin
+    y <= x(0) xor x(1) xor x(2) xor x(3);
+end architecture;
+
+-------------------------------------------------------------------------------
+
+entity issue251 is
+end entity;
+
+architecture test of issue251 is
+    signal a : bit_vector(3 downto 0);
+    signal b : bit_vector(1 downto 0);
+begin
+
+    sub1_i: entity work.sub
+        port map (
+            x(-1) => a(0),               -- Error
+            x(3 downto 0) => a,
+            y => open );
+
+    sub2_i: entity work.sub
+        port map (
+            x(3) => a(-1),               -- Error
+            x(2 downto 0) => a,
+            y => open );
+
+end architecture;
diff --git a/test/test_elab.c b/test/test_elab.c
index 3539d0ca..731a7574 100644
--- a/test/test_elab.c
+++ b/test/test_elab.c
@@ -400,6 +400,21 @@ START_TEST(test_libbind3)
 }
 END_TEST
 
+START_TEST(test_issue251)
+{
+   input_from_file(TESTDIR "/elab/issue251.vhd");
+
+   const error_t expect[] = {
+      { 24, "array X index -1 out of bounds 3 downto 0" },
+      { 30, "array A index -1 out of bounds 3 downto 0" },
+      { -1, NULL }
+   };
+   expect_errors(expect);
+
+   fail_unless(run_elab() == NULL);
+}
+END_TEST
+
 int main(void)
 {
    Suite *s = suite_create("elab");
@@ -430,6 +445,7 @@ int main(void)
    tcase_add_test(tc, test_libbind2);
    tcase_add_test(tc, test_toplevel2);
    tcase_add_test(tc, test_libbind3);
+   tcase_add_test(tc, test_issue251);
    suite_add_tcase(s, tc);
 
    return nvc_run_test(s);
-- 
2.39.2