From 81e377023c490998a3fec245ca2fb2b3c710c2c6 Mon Sep 17 00:00:00 2001
From: Yusuke Endoh <mame@ruby-lang.org>
Date: Wed, 25 Dec 2019 13:35:22 +0900
Subject: [PATCH] range.c: Range#min with a beginless one now raise an explicit
 exception

[Bug #16450]
---
 range.c                 | 7 +++++++
 test/ruby/test_range.rb | 6 ++++++
 2 files changed, 13 insertions(+)

diff --git a/range.c b/range.c
index fe956197c6..bf14c0c7a7 100644
--- a/range.c
+++ b/range.c
@@ -1136,6 +1136,10 @@ range_last(int argc, VALUE *argv, VALUE range)
 static VALUE
 range_min(int argc, VALUE *argv, VALUE range)
 {
+    if (NIL_P(RANGE_BEG(range))) {
+	rb_raise(rb_eRangeError, "cannot get the minimum of beginless range");
+    }
+
     if (rb_block_given_p()) {
         if (NIL_P(RANGE_END(range))) {
             rb_raise(rb_eRangeError, "cannot get the minimum of endless range with custom comparison method");
@@ -1185,6 +1189,9 @@ range_max(int argc, VALUE *argv, VALUE range)
     }
 
     if (rb_block_given_p() || (EXCL(range) && !nm) || argc) {
+        if (NIL_P(RANGE_BEG(range))) {
+            rb_raise(rb_eRangeError, "cannot get the maximum of beginless range with custom comparison method");
+        }
         return rb_call_super(argc, argv);
     }
     else {
diff --git a/test/ruby/test_range.rb b/test/ruby/test_range.rb
index 800cee92cc..b37dbbc433 100644
--- a/test/ruby/test_range.rb
+++ b/test/ruby/test_range.rb
@@ -81,6 +81,8 @@ class TestRange < Test::Unit::TestCase
     assert_equal(nil, (2..1).min)
     assert_equal(1, (1...2).min)
     assert_equal(1, (1..).min)
+    assert_raise(RangeError) { (..1).min }
+    assert_raise(RangeError) { (...1).min }
 
     assert_equal(1.0, (1.0..2.0).min)
     assert_equal(nil, (2.0..1.0).min)
@@ -93,6 +95,8 @@ class TestRange < Test::Unit::TestCase
     assert_equal([0,1,2], (0..10).min(3))
     assert_equal([0,1], (0..1).min(3))
     assert_equal([0,1,2], (0..).min(3))
+    assert_raise(RangeError) { (..1).min(3) }
+    assert_raise(RangeError) { (...1).min(3) }
 
     assert_raise(RangeError) { (0..).min {|a, b| a <=> b } }
   end
@@ -119,6 +123,8 @@ class TestRange < Test::Unit::TestCase
     assert_equal([9,8,7], (0...10).max(3))
     assert_raise(RangeError) { (1..).max(3) }
     assert_raise(RangeError) { (1...).max(3) }
+
+    assert_raise(RangeError) { (..0).min {|a, b| a <=> b } }
   end
 
   def test_minmax