From 71ce7e1825c5b8fe08dd96cd77c6a379afd34256 Mon Sep 17 00:00:00 2001
From: Nobuyoshi Nakada <nobu@ruby-lang.org>
Date: Sun, 15 Jan 2023 13:03:27 +0900
Subject: [Bug #19335] `Integer#remainder` should respect `#coerce` (#7120)

Also `Numeric#remainder` should.
---
 numeric.c                                | 21 +++++++++++++++++----
 spec/ruby/core/numeric/remainder_spec.rb |  3 +++
 test/ruby/test_float.rb                  |  6 ++++++
 test/ruby/test_integer_comb.rb           | 23 ++++++++++++++++++-----
 4 files changed, 44 insertions(+), 9 deletions(-)

diff --git a/numeric.c b/numeric.c
index 0312f4939f..15729e4728 100644
--- a/numeric.c
+++ b/numeric.c
@@ -740,6 +740,9 @@ num_modulo(VALUE x, VALUE y)
 static VALUE
 num_remainder(VALUE x, VALUE y)
 {
+    if (!rb_obj_is_kind_of(y, rb_cNumeric)) {
+        do_coerce(&x, &y, TRUE);
+    }
     VALUE z = num_funcall1(x, '%', y);
 
     if ((!rb_equal(z, INT2FIX(0))) &&
@@ -4363,12 +4366,22 @@ static VALUE
 int_remainder(VALUE x, VALUE y)
 {
     if (FIXNUM_P(x)) {
-        return num_remainder(x, y);
+        if (FIXNUM_P(y)) {
+            VALUE z = fix_mod(x, y);
+            assert(FIXNUM_P(z));
+            if (z != INT2FIX(0) && (SIGNED_VALUE)(x ^ y) < 0)
+                z = fix_minus(z, y);
+            return z;
+        }
+        else if (!RB_BIGNUM_TYPE_P(y)) {
+            return num_remainder(x, y);
+        }
+        x = rb_int2big(FIX2LONG(x));
     }
-    else if (RB_BIGNUM_TYPE_P(x)) {
-        return rb_big_remainder(x, y);
+    else if (!RB_BIGNUM_TYPE_P(x)) {
+        return Qnil;
     }
-    return Qnil;
+    return rb_big_remainder(x, y);
 }
 
 static VALUE
diff --git a/spec/ruby/core/numeric/remainder_spec.rb b/spec/ruby/core/numeric/remainder_spec.rb
index 1e2f5f3a96..674fa22d8e 100644
--- a/spec/ruby/core/numeric/remainder_spec.rb
+++ b/spec/ruby/core/numeric/remainder_spec.rb
@@ -6,6 +6,9 @@ describe "Numeric#remainder" do
     @obj    = NumericSpecs::Subclass.new
     @result = mock("Numeric#% result")
     @other  = mock("Passed Object")
+    ruby_version_is "3.3" do
+      @other.should_receive(:coerce).with(@obj).and_return([@obj, @other])
+    end
   end
 
   it "returns the result of calling self#% with other if self is 0" do
diff --git a/test/ruby/test_float.rb b/test/ruby/test_float.rb
index 35cde1e951..b91b904d1e 100644
--- a/test/ruby/test_float.rb
+++ b/test/ruby/test_float.rb
@@ -227,6 +227,12 @@ class TestFloat < Test::Unit::TestCase
     assert_equal(-3.5, (-11.5).remainder(-4))
     assert_predicate(Float::NAN.remainder(4), :nan?)
     assert_predicate(4.remainder(Float::NAN), :nan?)
+
+    ten = Object.new
+    def ten.coerce(other)
+      [other, 10]
+    end
+    assert_equal(4, 14.0.remainder(ten))
   end
 
   def test_to_s
diff --git a/test/ruby/test_integer_comb.rb b/test/ruby/test_integer_comb.rb
index 1ad13dd31b..150f45cfd7 100644
--- a/test/ruby/test_integer_comb.rb
+++ b/test/ruby/test_integer_comb.rb
@@ -408,19 +408,32 @@ class TestIntegerComb < Test::Unit::TestCase
   end
 
   def test_remainder
+    coerce = EnvUtil.labeled_class("CoerceNum") do
+      def initialize(num)
+        @num = num
+      end
+      def coerce(other)
+        [other, @num]
+      end
+      def inspect
+        "#{self.class.name}(#@num)"
+      end
+      alias to_s inspect
+    end
+
     VS.each {|a|
-      VS.each {|b|
-        if b == 0
+      (VS + VS.map {|b| [coerce.new(b), b]}).each {|b, i = b|
+        if i == 0
           assert_raise(ZeroDivisionError) { a.divmod(b) }
         else
-          r = a.remainder(b)
+          r = assert_nothing_raised(ArgumentError, "#{a}.remainder(#{b})") {a.remainder(b)}
           assert_kind_of(Integer, r)
           if a < 0
-            assert_operator(-b.abs, :<, r, "#{a}.remainder(#{b})")
+            assert_operator(-i.abs, :<, r, "#{a}.remainder(#{b})")
             assert_operator(0, :>=, r, "#{a}.remainder(#{b})")
           elsif 0 < a
             assert_operator(0, :<=, r, "#{a}.remainder(#{b})")
-            assert_operator(b.abs, :>, r, "#{a}.remainder(#{b})")
+            assert_operator(i.abs, :>, r, "#{a}.remainder(#{b})")
           else
             assert_equal(0, r, "#{a}.remainder(#{b})")
           end
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