vala: Correctly replace "in" expression in pre-/postconditions of method

Fixes https://gitlab.gnome.org/GNOME/vala/issues/1269

tests/Makefile.am

@@ -188,6 +188,7 @@ TESTS = \
 	methods/preconditions-temp-variables.vala \
 	methods/prepostconditions.vala \
 	methods/prepostconditions-captured.vala \
+	methods/prepostconditions-contains.vala \
 	methods/postconditions.vala \
 	methods/postconditions-temp-variables.vala \
 	methods/return-unowned-delegate.vala \

tests/methods/prepostconditions-contains.c-expected

+/* methods_prepostconditions_contains.c generated by valac, the Vala compiler
+ * generated from methods_prepostconditions_contains.vala, do not modify */
+
+#include <stdlib.h>
+#include <string.h>
+#include <glib.h>
+
+#if !defined(VALA_EXTERN)
+#if defined(_MSC_VER)
+#define VALA_EXTERN __declspec(dllexport) extern
+#elif __GNUC__ >= 4
+#define VALA_EXTERN __attribute__((visibility("default"))) extern
+#else
+#define VALA_EXTERN extern
+#endif
+#endif
+
+#define _g_free0(var) (var = (g_free (var), NULL))
+#define _vala_assert(expr, msg) if G_LIKELY (expr) ; else g_assertion_message_expr (G_LOG_DOMAIN, __FILE__, __LINE__, G_STRFUNC, msg);
+#define _vala_return_if_fail(expr, msg) if G_LIKELY (expr) ; else { g_return_if_fail_warning (G_LOG_DOMAIN, G_STRFUNC, msg); return; }
+#define _vala_return_val_if_fail(expr, msg, val) if G_LIKELY (expr) ; else { g_return_if_fail_warning (G_LOG_DOMAIN, G_STRFUNC, msg); return val; }
+#define _vala_warn_if_fail(expr, msg) if G_LIKELY (expr) ; else g_warn_message (G_LOG_DOMAIN, __FILE__, __LINE__, G_STRFUNC, msg);
+
+VALA_EXTERN void foo (const gchar* s);
+static gboolean _vala_string_array_contains (const gchar* * stack,
+                                      gssize stack_length,
+                                      const const gchar* needle);
+VALA_EXTERN gchar* bar (void);
+static void _vala_main (void);
+
+const gchar* array[3] = {"foo", "bar", "manam"};
+
+static gboolean
+_vala_string_array_contains (const gchar* * stack,
+                             gssize stack_length,
+                             const const gchar* needle)
+{
+	gssize i;
+	for (i = 0; i < stack_length; i++) {
+		if (g_strcmp0 (stack[i], needle) == 0) {
+			return TRUE;
+		}
+	}
+	return FALSE;
+}
+
+void
+foo (const gchar* s)
+{
+	g_return_if_fail (s != NULL);
+	_vala_return_if_fail (_vala_string_array_contains (array, G_N_ELEMENTS (array), s), "s in array");
+}
+
+gchar*
+bar (void)
+{
+	gchar* _tmp0_;
+	gchar* result = NULL;
+	_tmp0_ = g_strdup ("manam");
+	result = _tmp0_;
+	_vala_warn_if_fail (_vala_string_array_contains (array, G_N_ELEMENTS (array), result), "result in array");
+	return result;
+}
+
+static void
+_vala_main (void)
+{
+	gchar* _tmp0_;
+	gchar* _tmp1_;
+	foo ("bar");
+	_tmp0_ = bar ();
+	_tmp1_ = _tmp0_;
+	_g_free0 (_tmp1_);
+}
+
+int
+main (int argc,
+      char ** argv)
+{
+	_vala_main ();
+	return 0;
+}
+

tests/methods/prepostconditions-contains.vala

+const string[] array = { "foo", "bar", "manam" };
+
+void foo (string s) requires (s in array) {
+}
+
+string bar () ensures (result in array) {
+	return "manam";
+}
+
+void main () {
+	foo ("bar");
+	bar ();
+}

vala/valamethod.vala

@@ -577,6 +577,23 @@ public class Vala.Method : Subroutine, Callable {
 		}
 	}
 
+	public override void replace_expression (Expression old_node, Expression new_node) {
+		if (preconditions != null) {
+			var index = preconditions.index_of (old_node);
+			if (index >= 0) {
+				preconditions[index] = new_node;
+				new_node.parent_node = this;
+			}
+		}
+		if (postconditions != null) {
+			var index = postconditions.index_of (old_node);
+			if (index >= 0) {
+				postconditions[index] = new_node;
+				new_node.parent_node = this;
+			}
+		}
+	}
+
 	public override void replace_type (DataType old_type, DataType new_type) {
 		if (base_interface_type == old_type) {
 			base_interface_type = new_type;