Parser error when combining block statement and indexing with `begin`

[cvigilv]

Hi! I am currently seeing the following error whenever I want to parse the following example:

X = [1,2,3]

result = begin
    x = X[begin]
    y = X[begin+1]
    z = X[begin+2]
end

I get the following tree:

(ERROR ; [0, 0] - [7, 0]
  (assignment ; [0, 0] - [0, 11]
    (identifier) ; [0, 0] - [0, 1]
    (operator) ; [0, 2] - [0, 3]
    (vector_expression ; [0, 4] - [0, 11]
      (integer_literal) ; [0, 5] - [0, 6]
      (integer_literal) ; [0, 7] - [0, 8]
      (integer_literal))) ; [0, 9] - [0, 10]
  (identifier) ; [2, 0] - [2, 6]
  (assignment ; [3, 4] - [3, 16]
    (identifier) ; [3, 4] - [3, 5]
    (operator) ; [3, 6] - [3, 7]
    (index_expression ; [3, 8] - [3, 16]
      (identifier) ; [3, 8] - [3, 9]
      (vector_expression ; [3, 9] - [3, 16]
        (identifier)))) ; [3, 10] - [3, 15]
  (identifier) ; [4, 4] - [4, 5]
  (identifier) ; [4, 8] - [4, 9]
  (matrix_row ; [4, 10] - [4, 15]
    (identifier)) ; [4, 10] - [4, 15]
  (ERROR ; [4, 15] - [7, 0]
    (unary_expression ; [4, 15] - [4, 17]
      (operator) ; [4, 15] - [4, 16]
      (integer_literal)) ; [4, 16] - [4, 17]
    (ERROR) ; [4, 17] - [4, 18]
    (identifier) ; [5, 4] - [5, 5]
    (identifier) ; [5, 8] - [5, 9]
    (compound_statement ; [5, 10] - [6, 3]
      (unary_expression ; [5, 15] - [5, 17]
        (operator) ; [5, 15] - [5, 16]
        (integer_literal)) ; [5, 16] - [5, 17]
      (ERROR)))) ; [5, 17] - [5, 18]

But not when I invert the order of the elements inside the slicing, for example:

X = [1,2,3]

result = begin
    x = X[begin]
    y = X[1+begin]
    z = X[2+begin]
end

where I obtain the following tree:

(source_file ; [0, 0] - [7, 0]
  (assignment ; [0, 0] - [0, 11]
    (identifier) ; [0, 0] - [0, 1]
    (operator) ; [0, 2] - [0, 3]
    (vector_expression ; [0, 4] - [0, 11]
      (integer_literal) ; [0, 5] - [0, 6]
      (integer_literal) ; [0, 7] - [0, 8]
      (integer_literal))) ; [0, 9] - [0, 10]
  (assignment ; [2, 0] - [6, 3]
    (identifier) ; [2, 0] - [2, 6]
    (operator) ; [2, 7] - [2, 8]
    (compound_statement ; [2, 9] - [6, 3]
      (assignment ; [3, 4] - [3, 16]
        (identifier) ; [3, 4] - [3, 5]
        (operator) ; [3, 6] - [3, 7]
        (index_expression ; [3, 8] - [3, 16]
          (identifier) ; [3, 8] - [3, 9]
          (vector_expression ; [3, 9] - [3, 16]
            (identifier)))) ; [3, 10] - [3, 15]
      (assignment ; [4, 4] - [4, 18]
        (identifier) ; [4, 4] - [4, 5]
        (operator) ; [4, 6] - [4, 7]
        (index_expression ; [4, 8] - [4, 18]
          (identifier) ; [4, 8] - [4, 9]
          (vector_expression ; [4, 9] - [4, 18]
            (binary_expression ; [4, 10] - [4, 17]
              (integer_literal) ; [4, 10] - [4, 11]
              (operator) ; [4, 11] - [4, 12]
              (identifier))))) ; [4, 12] - [4, 17]
      (assignment ; [5, 4] - [5, 18]
        (identifier) ; [5, 4] - [5, 5]
        (operator) ; [5, 6] - [5, 7]
        (index_expression ; [5, 8] - [5, 18]
          (identifier) ; [5, 8] - [5, 9]
          (vector_expression ; [5, 9] - [5, 18]
            (binary_expression ; [5, 10] - [5, 17]
              (integer_literal) ; [5, 10] - [5, 11]
              (operator) ; [5, 11] - [5, 12]
              (identifier)))))))) ; [5, 12] - [5, 17]

This may be related to #127

[savq]

Yes, it's the same error as 127. I'll close this as a duplicate to not get confused later.