Bugfix for accidental violation of immutable value guarantees due to

inner field members

1 files changed, 47 insertions, 0 deletions

diff --git a/test/values.tm b/test/values.tm
new file mode 100644
index 00000000..86f34a89
--- /dev/null
+++ b/test/values.tm
@@ -0,0 +1,47 @@
+# Tests for ensuring immutable value nature in various contexts
+struct Inner(xs:[Int32])
+
+struct Outer(inner:Inner)
+
+func sneaky(outer:Outer)
+    (&outer.inner.xs)[1] = 99
+
+func sneaky2(outer:&Outer)
+    (&outer.inner.xs)[1] = 99
+
+func main()
+    do
+        xs := [10, 20, 30]
+        copy := xs
+        (&xs)[1] = 99
+        assert xs == [99, 20, 30]
+        assert copy == [10, 20, 30]
+
+    do
+        t := {"A":10, "B":20}
+        copy := t
+        (&t)["A"] = 99
+        assert t == {"A":99, "B":20}
+        assert copy == {"A":10, "B":20}
+
+    do
+        foo := Outer(Inner([10, 20, 30]))
+        copy := foo
+        (&foo.inner.xs)[1] = 99
+        assert foo.inner.xs == [99, 20, 30]
+        assert copy.inner.xs == [10, 20, 30]
+
+    do
+        foo := Outer(Inner([10, 20, 30]))
+        copy := foo
+        sneaky(foo)
+        assert foo.inner.xs == [10, 20, 30]
+        assert copy.inner.xs == [10, 20, 30]
+
+    do
+        foo := Outer(Inner([10, 20, 30]))
+        copy := foo
+        sneaky2(&foo)
+        assert foo.inner.xs == [99, 20, 30]
+        assert copy.inner.xs == [10, 20, 30]
+