test: add more error test cases on wrong assign targets

Signed-off-by: peefy <[email protected]>

kclvm/parser/src/parser/stmt.rs

@@ -306,6 +306,7 @@ impl<'a> Parser<'a> {
                         None
                     }
                 })
+                // Drop error assign target nodes.
                 .flatten()
                 .collect();
 
@@ -369,6 +370,7 @@ impl<'a> Parser<'a> {
                                 None
                             }
                         })
+                        // Drop error assign target nodes.
                         .flatten()
                         .collect();
                     Some(Box::new(Node::node_with_pos(

test/grammar/assign/assign_fail_2/main.k

@@ -0,0 +1,2 @@
+_a = [1, 2, 3]
+_a[1:2] = [2, 3]

test/grammar/assign/assign_fail_2/stderr.golden

@@ -0,0 +1 @@
+'SubscriptExpression' is an illegal expression for assignment, because the left-hand side of an assignment expression may not be a slice access

test/grammar/assign/assign_fail_3/main.k

@@ -0,0 +1,2 @@
+_a = {}
+_a?.b = "value"

test/grammar/assign/assign_fail_3/stderr.golden

@@ -0,0 +1 @@
+'SelectorExpression' is an illegal expression for assignment, because the left-hand side of an assignment expression may not be an optional attribute access.

test/grammar/assign/assign_fail_4/main.k

@@ -0,0 +1 @@
+_a + 1 = 2

test/grammar/assign/assign_fail_4/stderr.golden

@@ -0,0 +1 @@
+'BinaryExpression' is an illegal expression for assignment

test/grammar/assign/assign_fail_5/main.k

@@ -0,0 +1 @@
+[1] = 2

test/grammar/assign/assign_fail_5/stderr.golden

@@ -0,0 +1 @@
+'ListExpression' is an illegal expression for assignment

test/grammar/assign/assign_fail_6/main.k

@@ -0,0 +1 @@
+_f() = 2

test/grammar/assign/assign_fail_6/stderr.golden

@@ -0,0 +1 @@
+'CallExpression' is an illegal expression for assignment