From 296c150312dcaedecb119b04d51273d65264aad2 Mon Sep 17 00:00:00 2001
From: Nick Gasson <nick@nickg.me.uk>
Date: Fri, 19 Jan 2024 19:49:10 +0000
Subject: [PATCH] Fix crash dumping subtype that cannot be represented in FST

Issue #840
---
 src/rt/wave.c                   |  6 +++++-
 test/regress/gold/issue840.dump |  2 ++
 test/regress/issue840.vhd       | 23 +++++++++++++++++++++++
 test/regress/testlist.txt       |  1 +
 4 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 test/regress/gold/issue840.dump
 create mode 100644 test/regress/issue840.vhd

diff --git a/src/rt/wave.c b/src/rt/wave.c
index b6c99f25..3fc80820 100644
--- a/src/rt/wave.c
+++ b/src/rt/wave.c
@@ -270,7 +270,11 @@ static fst_type_t *fst_type_for(type_t type, const loc_t *loc)
    switch (type_kind(type)) {
    case T_SUBTYPE:
       {
-         *ft = *fst_type_for(type_base(type), loc);
+         fst_type_t *baseft = fst_type_for(type_base(type), loc);
+         if (baseft == NULL)
+            goto poison;
+
+         *ft = *baseft;
 
          switch (is_well_known(type_ident(type))) {
          case W_STD_NATURAL:  ft->sdt = FST_SDT_VHDL_NATURAL; break;
diff --git a/test/regress/gold/issue840.dump b/test/regress/gold/issue840.dump
new file mode 100644
index 00000000..b3dffa29
--- /dev/null
+++ b/test/regress/gold/issue840.dump
@@ -0,0 +1,2 @@
+#0 issue840.t 00000000000000000000000000000001
+#1000000 issue840.t 00000000000000000000000000000010
diff --git a/test/regress/issue840.vhd b/test/regress/issue840.vhd
new file mode 100644
index 00000000..4dcfc245
--- /dev/null
+++ b/test/regress/issue840.vhd
@@ -0,0 +1,23 @@
+entity issue840 is
+end entity;
+
+architecture test of issue840 is
+    type t_array2d is array (natural range <>, natural range <>) of bit;
+    subtype t_sub is t_array2d(1 to 3, 1 to 3);
+
+    signal s : t_sub;
+    signal t : integer;
+begin
+
+    process is
+    begin
+        s <= ("101", "110", "111");
+        t <= 1;
+        wait for 1 ns;
+        s <= ("110", "000", "101");
+        t <= 2;
+        wait for 1 ns;
+        wait;
+    end process;
+
+end architecture;
diff --git a/test/regress/testlist.txt b/test/regress/testlist.txt
index dc2744d4..ff221af3 100644
--- a/test/regress/testlist.txt
+++ b/test/regress/testlist.txt
@@ -925,3 +925,4 @@ cover22         shell
 issue831        normal,2008
 issue829        normal
 issue839        normal
+issue840        wave
-- 
2.39.2