`tree-sitter-fortran` errors parsing an assignment to an array called `if`

[inaki-amatria]

• tree-sitter-fortran version is: 64e11001d7ef3e8ac18e55a3a2d811fe36430923
• Reduced test case is:

! foo.f90
program main
  integer, dimension(10, 10) :: if
  do i = 1, 10
    if(i, i) = 0
  end do
end

• Current behavior:

(translation_unit [0, 0] - [7, 0]
  (comment [0, 0] - [0, 9])
  (program [1, 0] - [7, 0]
    (program_statement [1, 0] - [2, 0]
      (name [1, 8] - [1, 12]))
    (variable_declaration [2, 2] - [2, 34]
      type: (intrinsic_type [2, 2] - [2, 9])
      attribute: (type_qualifier [2, 11] - [2, 28]
        (argument_list [2, 20] - [2, 28]
          (number_literal [2, 21] - [2, 23])
          (number_literal [2, 25] - [2, 27])))
      declarator: (identifier [2, 32] - [2, 34]))
    (do_loop_statement [3, 2] - [5, 8]
      (loop_control_expression [3, 5] - [3, 14]
        (identifier [3, 5] - [3, 6])
        (number_literal [3, 9] - [3, 10])
        (number_literal [3, 12] - [3, 14]))
      (assignment_statement [4, 4] - [4, 16]
        left: (identifier [4, 4] - [4, 6])
        (ERROR [4, 6] - [4, 12]
          (parenthesized_expression [4, 6] - [4, 12]
            (identifier [4, 7] - [4, 8])
            (ERROR [4, 8] - [4, 11])))
        right: (number_literal [4, 15] - [4, 16]))
      (end_do_loop_statement [5, 2] - [5, 8]))
    (end_program_statement [6, 0] - [7, 0])))
foo.f90	   0.53 ms	   196 bytes/ms	(ERROR [4, 6] - [4, 12])

• Expected behavior: tree-sitter-fortran parses line 5 as an assignment statement

[ZedThree]

Here's what it should parse as:

(translation_unit
  (program
    (program_statement
      (name))
    (variable_declaration
      type: (intrinsic_type)
      attribute: (type_qualifier
        (argument_list
          (number_literal)
          (number_literal)))
      declarator: (identifier))
    (do_loop_statement
      (loop_control_expression
        (identifier)
        (number_literal)
        (number_literal))
      (assignment_statement
        left: (call_expression
          (identifier)
          (argument_list
            (identifier)
            (identifier)))
        right: (number_literal))
      (end_do_loop_statement))
    (end_program_statement)))

The errors are a bit weird, it does seem to recognise if as an identifier here, and not as a keyword.

There is an existing testcase Keywords As Identifiers, but that uses function as an array, which I guess might be handled better because that cannot appear in this context at all.

Root cause is probably same as #134