Invalid Array type with splat operator

[pocke]

Steep determines an invalid type for Array literal with splat operator.

Example:

# test.rb
array = [*'0'..'9']

p 'a' + array[0]

# Steepfile
target :lib do
  check 'test.rb'
end

$ steep check
# Type checking files:

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

test.rb:3:8: [error] Cannot pass a value of type `::Range[::String]` as an argument of type `::string`
│   ::Range[::String] <: ::string
│     ::Range[::String] <: (::String | ::_ToStr)
│       ::Range[::String] <: ::String
│         ::Object <: ::String
│           ::BasicObject <: ::String
│
│ Diagnostic ID: Ruby::ArgumentTypeMismatch
│
└ p 'a' + array[0]
          ~~~~~~~~

Detected 1 problem from 1 file

The array[0] should be ::String, but Steep determines the type as ::Range[::String]. So it prints an unexpected type error.

On [*x], Ruby calls x.to_a and expand the returned array to the array literal. But Steep just uses x as the array literal's type parameter.