[Bug #21513] Raise on converting endless range to set

ref: https://bugs.ruby-lang.org/issues/21513

Before this patch, trying to convert endless range (e.g. `(1..)`) to set
(using `to_set`) would hang

Author: viralpraxis

set.c

@@ -505,6 +505,14 @@ set_i_initialize(int argc, VALUE *argv, VALUE set)
             }
         }
         else {
+            ID id_size = rb_intern("size");
+            if (rb_obj_is_kind_of(other, rb_mEnumerable) && rb_respond_to(other, id_size)) {
+                VALUE size = rb_funcall(other, id_size, 0);
+                if (RB_TYPE_P(size, T_FLOAT) && RFLOAT_VALUE(size) == INFINITY) {
+                    rb_raise(rb_eArgError, "cannot initialize Set from an object with infinite size");
+                }
+            }
+
             rb_block_call(other, enum_method_id(other), 0, 0,
                 rb_block_given_p() ? set_initialize_with_block : set_initialize_without_block,
                 set);

test/ruby/test_set.rb

@@ -81,6 +81,20 @@ def test_s_new
 
     s = Set.new(ary) { |o| o * 2 }
     assert_equal([2,4,6], s.sort)
+
+    assert_raise(ArgumentError) {
+      Set.new((1..))
+    }
+    assert_raise(ArgumentError) {
+      Set.new((1..), &:succ)
+    }
+    assert_raise(ArgumentError) {
+      Set.new(1.upto(Float::INFINITY))
+    }
+
+    assert_raise(ArgumentError) {
+      Set.new(Object.new)
+    }
   end
 
   def test_clone