Merge pull request #1165 from soutaro/fix-ffi

Fix subtyping issues

doc/shape.md

@@ -24,7 +24,9 @@ Shape (_Foo) {
 Note that the `self` type in the example is resolved to `_Foo` during shape calculation.
 
 The shape calculation of an object is straightforward. Calculate a `RBS::Definition` of a class singleton/instance, or an interface, and translate the data structure to a `Shape` object. But there are a few things to consider.
+
 ## Tuple, record, and proc types
+
 The shape of tuple, record, or proc types are based on their base types -- Array, Hash, or Proc classes --, but with specialized method types.
 
 ```
@@ -37,16 +39,22 @@ Shape ([Integer, String]) {
 ```
 
 The specialization is implemented as a part of shape calculation.
+
 ## Special methods
+
 Steep recognizes some special methods for type narrowing, including `#is_a?`, `#===`, `#nil?`, ... These methods are defined with normal RBS syntax, but the method types in shapes are transformed to types using logic types.
 
 The shape calculation inserts the specialized methods with these special methods.
+
 ## `self` types
+
 There are two cases of `self` types to consider during shape calculation.
 
 1. `self` types included in the shape of a type
 2. `self` types included in given types
+
 ### 1. `self` types included in the shape of a type
+
 `self` types may be included in a class or interface definition.
 
 ```rbs
@@ -62,7 +70,9 @@ Shape (_Foo) {
   itself: () -> _Foo
 }
 ```
+
 ### 2. `self` types included in given types
+
 Unlike `self` types included in definitions, `self` types in given types should be preserved.
 
 ```rbs
@@ -100,7 +110,9 @@ end
 ```
 
 We want the type of `foo.get` to be `self`, not `Foo`, to avoid a type error being detected.
+
 ## Shape of `self` types
+
 We also want `self` type if `self` is the type of the shape.
 
 ```rb
@@ -154,21 +166,27 @@ Shape (Foo | Bar) {
 So, the resulting type of `self.foo` where the type of `self` is `Foo | Bar`, would be `Integer | Foo | Bar`. But, actually, it won't be `Foo` because the `self` comes from `Bar`.
 
 This is an incorrect result, but Steep is doing this right now.
+
 ## `class` and `instance` types
+
 The shape calculation provides limited support for `class` and `instance` types.
 
 1. `class`/`instance` types from the definition are resolved
 2. `class`/`instance` types in generics type arguments of interfaces/instances are preserved
 3. Shape of `class`/`instance` types are resolved to configuration's `class_type` and `instance_type`, and the translated types are used to calculate the shape
 
 It's different from `self` types except case #2. The relationship between `self`/`class`/`instance` is not trivial in Ruby. All of them might be resolved to any type, which means calculating one from another of them is simply impossible.
+
 ## Public methods, private methods
+
 `Shape` objects have a flag of if the shape is for *public* method calls or *private* method calls. Private method call is a form of `foo()` or `self.foo()` -- when the receiver is omitted or `self`. Public method calls are anything else.
 
 The shape calculation starts with *private methods*, and the `Shape#public_shape` method returns another shape that only has *public* methods.
 
 > Note that the private shape calculation is required even on public method calls. This means a possible chance of future optimizations.
+
 ## Lazy method type calculation
+
 We rarely need all of the methods available for an object. If we want to type check a method call, we only need the method type of that method. All other methods can be just ignored.
 
 *Lazy method type calculation* is introduced for that case. Instead of calculating the types of all of the methods, it registers a block that computes the method type.

lib/steep/interface/builder.rb

@@ -9,8 +9,6 @@ def initialize(self_type:, class_type: nil, instance_type: nil, variable_bounds:
           @class_type = class_type
           @instance_type = instance_type
           @variable_bounds = variable_bounds
-
-          validate
         end
 
         def self.empty
@@ -23,11 +21,16 @@ def subst
           end
         end
 
-        def validate
+        def validate_self_type
           validate_fvs(:self_type, self_type)
+        end
+
+        def validate_instance_type
           validate_fvs(:instance_type, instance_type)
+        end
+
+        def validate_class_type
           validate_fvs(:class_type, class_type)
-          self
         end
 
         def validate_fvs(name, type)
@@ -37,6 +40,7 @@ def validate_fvs(name, type)
               raise "#{name} cannot include 'self' type: #{type}"
             end
             if fvs.include?(AST::Types::Instance.instance)
+              Steep.logger.fatal { "#{name} cannot include 'instance' type: #{type}" }
               raise "#{name} cannot include 'instance' type: #{type}"
             end
             if fvs.include?(AST::Types::Class.instance)
@@ -87,12 +91,15 @@ def fetch_cache(cache, key)
       def raw_shape(type, config)
         case type
         when AST::Types::Self
+          config.validate_self_type
           self_type = config.self_type or raise
           self_shape(self_type, config)
         when AST::Types::Instance
+          config.validate_instance_type
           instance_type = config.instance_type or raise
           raw_shape(instance_type, config)
         when AST::Types::Class
+          config.validate_class_type
           klass_type = config.class_type or raise
           raw_shape(klass_type, config)
         when AST::Types::Name::Singleton