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

viralpraxis · viralpraxis · commit a5a7db6bf1a5 · 2025-07-16T02:52:13.000+04:00
Before this patch, trying to convert endless range (e.g. `(1..)`) to set
(using `to_set`) would hang
diff --git a/range.c b/range.c
@@ -1017,6 +1017,31 @@ range_to_a(VALUE range)
     return rb_call_super(0, 0);
 }
 
+/*
+ *  call-seq:
+ *    to_set -> set
+ *
+ *  Returns a set containing the elements in +self+, if a finite collection;
+ *  raises an exception otherwise.
+ *
+ *    (1..4).to_set     # => Set[1, 2, 3, 4]
+ *    (1...4).to_set    # => Set[1, 2, 3]
+ *    ('a'..'d').to_set # => Set["a", "b", "c", "d"]
+ *    (..'d').to_set    # RangeError
+ *    ('a'..).to_set    # RangeError
+ *
+ */
+
+
+static VALUE
+range_to_set(VALUE range)
+{
+    if (NIL_P(RANGE_BEG(range)) || NIL_P(RANGE_END(range))) {
+        rb_raise(rb_eRangeError, "cannot convert infinite range to a set");
+    }
+    return rb_call_super(0, 0);
+}
+
 static VALUE
 range_enum_size(VALUE range, VALUE args, VALUE eobj)
 {
@@ -2847,6 +2872,7 @@ Init_Range(void)
     rb_define_method(rb_cRange, "entries", range_to_a, 0);
     rb_define_method(rb_cRange, "to_s", range_to_s, 0);
     rb_define_method(rb_cRange, "inspect", range_inspect, 0);
+    rb_define_method(rb_cRange, "to_set", range_to_set, 0);
 
     rb_define_method(rb_cRange, "exclude_end?", range_exclude_end_p, 0);
 
diff --git a/test/ruby/test_range.rb b/test/ruby/test_range.rb
@@ -1541,4 +1541,14 @@ def test_overlap?
     assert_not_operator((1...3), :overlap?, (3..4))
     assert_not_operator((...3), :overlap?, (3..))
   end
+
+  def test_to_set
+    assert_equal(Set[], (1..-1).to_set)
+    assert_equal(Set[1, 2, 3], (1..3).to_set)
+    assert_equal(Set['a', 'b', 'c'], ('a'..'c').to_set)
+
+    assert_raise(RangeError) { (239..).to_set }
+    assert_raise(RangeError) { (...239).to_set }
+    assert_raise(RangeError) { (nil...nil).to_set }
+  end
 end
