Use correct field for self type resolution

lib/solargraph/pin/method.rb

@@ -92,7 +92,6 @@ def combine_with(other, attrs = {})
         end
         new_attrs = {
           visibility: combine_visibility(other),
-          # @sg-ignore https://github.com/castwide/solargraph/pull/1050
           explicit: explicit? || other.explicit?,
           block: combine_blocks(other),
           node: choose_node(other, :node),

lib/solargraph/source/chain.rb

@@ -271,12 +271,12 @@ def infer_from_definitions pins, context, api_map, locals
                else
                  ComplexType.new(types)
                end
-        if context.nil? || context.return_type.undefined?
+        if context.nil? || context.context.undefined?
           # up to downstream to resolve self type
           return type
         end
 
-        type.self_to_type(context.return_type)
+        type.self_to_type(context.context)
       end
 
       # @param type [ComplexType]

spec/type_checker/levels/alpha_spec.rb

@@ -0,0 +1,50 @@
+# frozen_string_literal: true
+
+describe Solargraph::TypeChecker do
+  context 'when at alpha level' do
+    def type_checker code
+      Solargraph::TypeChecker.load_string(code, 'test.rb', :alpha)
+    end
+
+    it 'resolves self correctly in arguments' do
+      checker = type_checker(%(
+        class Foo
+          # @param other [self]
+          #
+          # @return [String]
+          def bar other
+            other.bing
+          end
+
+          # @return [String]
+          def bing
+            'bing'
+          end
+        end
+      ))
+
+      expect(checker.problems.map(&:message)).to eq([])
+    end
+
+    it 'resolves self correctly in arguments (second case)' do
+      checker = type_checker(%(
+        class Blah
+          # @return [String]
+          attr_reader :filename
+
+          # @param filename [String]
+          def initialize filename
+            @filename = filename
+          end
+
+          # @param location [self]
+          def contain? location
+            filename == location.filename
+          end
+        end
+      ))
+
+      expect(checker.problems.map(&:message)).to eq([])
+    end
+  end
+end