cgen: fix assignment to the elements of an array of fixed arrays (#20133

)

vlib/v/gen/c/assign.v

@@ -429,8 +429,10 @@ fn (mut g Gen) assign_stmt(node_ ast.AssignStmt) {
 				pos := g.out.len
 				g.expr(left)
 
-				if g.is_arraymap_set && g.arraymap_set_pos > 0 {
-					g.go_back_to(g.arraymap_set_pos)
+				if g.is_arraymap_set && g.arraymap_set_pos >= 0 {
+					if g.arraymap_set_pos > 0 {
+						g.go_back_to(g.arraymap_set_pos)
+					}
 					g.write(', &${v_var})')
 					g.is_arraymap_set = false
 					g.arraymap_set_pos = 0

vlib/v/gen/c/index.v

@@ -224,10 +224,12 @@ fn (mut g Gen) index_of_array(node ast.IndexExpr, sym ast.TypeSymbol) {
 								else {}
 							}
 				*/
-				if need_wrapper {
-					g.write(', &(${elem_type_str}[]) { ')
-				} else {
-					g.write(', &')
+				if elem_sym.kind != .array_fixed {
+					if need_wrapper {
+						g.write(', &(${elem_type_str}[]) { ')
+					} else {
+						g.write(', &')
+					}
 				}
 			} else {
 				// `x[0] *= y`

vlib/v/tests/array_with_fixed_array_test.v

@@ -0,0 +1,16 @@
+fn fixed() [2]int {
+	return [9, 9]!
+}
+
+fn test_main() {
+	arr := [1, 2]!
+	mut net := [][2]int{len: 4}
+	net[1] = [1, 1]!
+	net[0] = net[1]
+	net[2] = arr
+	net[3] = fixed()
+	assert net[0] == [1, 1]!
+	assert net[1] == [1, 1]!
+	assert net[2] == [1, 2]!
+	assert net[3] == [9, 9]!
+}