Type check is not done when using rightward assignment to destructure the return value of a method

[rozner]

In case a method returns with a well defined hash then type checking works fine when you reference the values directly in the hash as seen with methods ok_direct and ok_indirect. However when using rightwards assignment no errors are given as seen with the rightward method.

Environment

$ ruby --version
ruby 3.2.2 (2023-03-30 revision e51014f9c0) [x86_64-linux]
$ steep --version
1.6.0
$ rbs --version
rbs 3.4.4

How to reproduce

# test.rb
module A
  def self.init
    { num: 1, str: 'str' }
  end

  def ok_direct
    init[:str].sqrt
  end

  def ok_indirect
    h = init
    num = h[:num]
    str = h[:str]

    str.sqrt
  end

  def rightward
    init => {num:, str:}
    str.sqrt
  end
end

# test.rbs
module A
  def init: () -> { num: Integer, str: String }
  def ok: () -> void
  def nok: () -> void
end

$ steep check

# Type checking files:

..............................................................F......................

lib/test.rb:7:15: [error] Type `::String` does not have method `sqrt`
│ Diagnostic ID: Ruby::NoMethod
│
└     init[:str].sqrt
                 ~~~~

lib/test.rb:15:8: [error] Type `::String` does not have method `sqrt`
│ Diagnostic ID: Ruby::NoMethod
│
└     str.sqrt
          ~~~~

Detected 2 problems from 1 file

[ksss]

Pattern matching is not yet supported in Steep. I believe the following is reported in the LSP.

Syntax `match_pattern` is not supported in Steep(Ruby::UnsupportedSyntax)