3 files changed, 20 insertions, 0 deletions
diff --git a/tests/programs/memdebug_interior.expected b/tests/programs/memdebug_interior.expected
new file mode 100644
index 0000000..580692a
--- /dev/null
+++ b/tests/programs/memdebug_interior.expected
@@ -0,0 +1 @@
+7 3 2
diff --git a/tests/programs/memdebug_interior.zc b/tests/programs/memdebug_interior.zc
new file mode 100644
index 0000000..8464f2c
--- /dev/null
+++ b/tests/programs/memdebug_interior.zc
@@ -0,0 +1,18 @@
+namespace;
+include rt;
+
+// memdebug finds the block of an interior pointer however deep it is: buf[255]
+// of a 256-word block is 255 words past its header, beyond the old 64-word scan.
+memdebug on;
+fn main() {
+	let buf = rt.new(256), small = rt.new(4);
+	buf[255] = 7;
+	buf[100] = 3;
+	small[3] = 2;
+	rt.put_n(buf[255]); rt.put_c(32);
+	rt.put_n(buf[100]); rt.put_c(32);
+	rt.put_n(small[3]); rt.put_c(10);
+	rt.free(small);
+	rt.free(buf);
+	return 0;
+}
diff --git a/tests/test.sh b/tests/test.sh
index 37fa71c..a4e58e8 100755
--- a/tests/test.sh
+++ b/tests/test.sh
@@ -188,6 +188,7 @@ ABC" "$l o3 lifts byte loads and stores"
 	chk "$($vm < tests/programs/strings.zc)" "hi! 3 3 104 i! 1 1 1 -42 42 -42 11 1 -9223372036854775808 0 1 3 10 1 1 1 W ab" "$l byte strings"
 	chk "$($vm < tests/programs/share.zc)" "1 2 1 4 1 1 1 1 42 1 1 1 6 0" "$l shared cons cells"
 	chk "$($vm < tests/programs/share_dbg.zc)" "7 1" "$l memdebug accepts a shared cell"
+	chk "$($vm < tests/programs/memdebug_interior.zc | md5sum)" "$(md5sum < tests/programs/memdebug_interior.expected)" "$l memdebug finds the block of a deep interior pointer"
 	chk "$($vm < tests/programs/global_transfer.zc)" "5 9" "$l an m or u owner stored in a global is transferred"
 	chk "$($vm < tests/programs/closure_result.zc)" "8 1.500000" "$l a closure with a declared result type"
 	chk "$($vm < examples/strings.zc)" "hello, zc