memdebug: obj_base finds the header from the buddy size classes, not a 64-word scan; regression program

2 files changed, 19 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;
+}