vala: SliceExpression need to return heap-allocated or unowned references

Fixes https://gitlab.gnome.org/GNOME/vala/issues/1120

3 files changed, 83 insertions, 0 deletions

diff --git a/tests/Makefile.am b/tests/Makefile.am
index ddac20684..e4a305f21 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -128,6 +128,7 @@ TESTS = \
 	arrays/resize-unowned-invalid.test \
 	arrays/resize-unowned-invalid-2.test \
 	arrays/resize-unowned-invalid-3.test \
+	arrays/slice-fixed-length.vala \
 	arrays/slice-invalid-start.test \
 	arrays/slice-invalid-stop.test \
 	arrays/slice-no-array.test \
diff --git a/tests/arrays/slice-fixed-length.vala b/tests/arrays/slice-fixed-length.vala
new file mode 100644
index 000000000..7b81f615a
--- /dev/null
+++ b/tests/arrays/slice-fixed-length.vala
@@ -0,0 +1,75 @@
+void manam (string[] foo) {
+	assert (foo.length == 2);
+	assert (foo[0] == "bar");
+	assert (foo[1] == "baz");
+}
+
+void minim (owned string[] foo) {
+	assert (foo.length == 2);
+	assert (foo[0] == "bar");
+	assert (foo[1] == "baz");
+}
+
+void main () {
+	string bar[4] = { "foo", "bar", "baz", "buzz" };
+	{
+		var foo = bar[1:3];
+		assert (foo.length == 2);
+		assert (foo[0] == "bar");
+		assert (foo[1] == "baz");
+	}
+	{
+		unowned var foo = bar[1:3];
+		assert (foo.length == 2);
+		assert (foo[0] == "bar");
+		assert (foo[1] == "baz");
+	}
+	{
+		int begin = 1;
+		var foo = bar[begin:3];
+		assert (foo.length == 2);
+		assert (foo[0] == "bar");
+		assert (foo[1] == "baz");
+	}
+	{
+		string[] foo = bar[1:3];
+		assert (foo.length == 2);
+		assert (foo[0] == "bar");
+		assert (foo[1] == "baz");
+	}
+	{
+		unowned string[] foo = bar[1:3];
+		assert (foo.length == 2);
+		assert (foo[0] == "bar");
+		assert (foo[1] == "baz");
+	}
+	{
+		int end = 3;
+		string[] foo = bar[1:end];
+		assert (foo.length == 2);
+		assert (foo[0] == "bar");
+		assert (foo[1] == "baz");
+	}
+	{
+		manam (bar[1:3]);
+	}
+	{
+		int begin = 1;
+		manam (bar[begin:3]);
+	}
+	{
+		int end = 3;
+		manam (bar[1:end]);
+	}
+	{
+		minim (bar[1:3]);
+	}
+	{
+		int begin = 1;
+		minim (bar[begin:3]);
+	}
+	{
+		int end = 3;
+		minim (bar[1:end]);
+	}
+}
diff --git a/vala/valasliceexpression.vala b/vala/valasliceexpression.vala
index 8eca80998..a9502b3e8 100644
--- a/vala/valasliceexpression.vala
+++ b/vala/valasliceexpression.vala
@@ -147,6 +147,13 @@ public class Vala.SliceExpression : Expression {
 		if (container.value_type is ArrayType) {
 			value_type = container.value_type.copy ();
 			value_type.value_owned = false;
+
+			// inline allocated results are not compatible with non-constant start/stop expressions
+			unowned ArrayType array_type = (ArrayType) value_type;
+			array_type.fixed_length = false;
+			array_type.inline_allocated = false;
+			array_type.length = null;
+
 			value_type.check (context);
 
 			/* check if the index is of type integer */