Merge pull request #841 from soutaro/case-untyped-nil

Make type of `case` node `untyped` rather than `nil`
soutaro · Jul 6, 2023 · c1b1a1e · c1b1a1e
2 parents 20834c6 + a1842ec
commit c1b1a1e
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diff --git a/lib/steep/type_construction.rb b/lib/steep/type_construction.rb
@@ -4477,6 +4477,9 @@ def union_type(*types)
 
     def union_type_unify(*types)
       types.inject do |type1, type2|
+        next type1 if type1.is_a?(AST::Types::Any)
+        next type2 if type2.is_a?(AST::Types::Any)
+
         unless no_subtyping?(sub_type: type1, super_type: type2)
           next type2
         end

diff --git a/test/type_check_test.rb b/test/type_check_test.rb
@@ -865,4 +865,33 @@ def test_branch_unreachable__logic_type
       YAML
     )
   end
+
+  def test_type_case__returns_nil_untyped_union
+    run_type_check_test(
+      signatures: {
+      },
+      code: {
+        "a.rb" => <<~RUBY
+          x = _ = 1
+          y = _ = 2
+          z = _ = 3
+
+          a =
+            case x
+            when :foo
+              y
+            when :bar
+              z
+            end
+
+          a.is_untyped
+        RUBY
+      },
+      expectations: <<~YAML
+        ---
+        - file: a.rb
+          diagnostics: []
+      YAML
+    )
+  end
 end