Compiler: fixed crash related to cast between unions having tuples. F…

…ixes #3377
crystal-lang · Oct 3, 2016 · 4733360 · 4733360
1 parent ab96652
commit 4733360
Showing 2 changed files with 15 additions and 1 deletion.
diff --git a/spec/compiler/codegen/cast_spec.cr b/spec/compiler/codegen/cast_spec.cr
@@ -349,4 +349,13 @@ describe "Code gen: cast" do
       x.try &.as(Foo)
       ))
   end
+
+  it "casts between union types, where union has a tuple type (#3377)" do
+    codegen(%(
+      require "prelude"
+
+      v = 1 || true || 1.0
+      (v || {v}).as(Bool | Float64)
+      ))
+  end
 end
diff --git a/src/compiler/crystal/codegen/cast.cr b/src/compiler/crystal/codegen/cast.cr
@@ -155,8 +155,13 @@ class Crystal::CodeGenVisitor
   end
 
   def needs_value_cast_inside_union?(value_type, union_type)
+    # A type needs a special cast if:
+    # 1. It's a tuple or named tuple
+    # 2. It's not inside the target union
+    # 3. There's a compatible type inside the target union
     return false unless value_type.is_a?(TupleInstanceType) || value_type.is_a?(NamedTupleInstanceType)
-    !union_type.union_types.any? &.==(value_type)
+    !union_type.union_types.any?(&.==(value_type)) &&
+      union_type.union_types.any? { |ut| value_type.implements?(ut) || ut.implements?(value_type) }
   end
 
   def assign_distinct_union_types(target_pointer, target_type, value_type, value)