[Bug #20697] Parse r suffix at Rational

Author: nobu

rational.c

@@ -2304,6 +2304,12 @@ islettere(int c)
     return (c == 'e' || c == 'E');
 }
 
+inline static int
+isletterr(int c)
+{
+    return (c == 'r' || c == 'R');
+}
+
 static VALUE
 negate_num(VALUE num)
 {
@@ -2353,7 +2359,13 @@ read_num(const char **s, const char *const end, VALUE *num, VALUE *nexp)
         ok = 1;
     }
 
-    if (ok && *s + 1 < end && islettere(**s)) {
+    if (!ok || *s >= end) {
+        /* failed or finish */
+    }
+    else if (isletterr(**s)) {
+        (*s)++;
+    }
+    else if (*s + 1 < end && islettere(**s)) {
         (*s)++;
         expsign = read_sign(s, end);
         exp = rb_int_parse_cstr(*s, end-*s, &e, NULL,

test/ruby/test_rational.rb

@@ -130,6 +130,7 @@ def test_conv_string
     assert_equal(Rational(111, 10), Rational('1.11e1'))
     assert_equal(Rational(111, 100), Rational('1.11e0'))
     assert_equal(Rational(111, 1000), Rational('1.11e-1'))
+    assert_equal(Rational(5, 4), Rational('3.0r','2.4R'))
   end
 
   def test_conv_error
@@ -842,6 +843,10 @@ def test_parse
     ng[5, 3, '5/3x']
 
     ng[5, 1, '5/-3']
+
+    ok[30, 24, '3.0r/2.4R']
+    ng[30, 24, '3.0r/2.4re1']
+    ng[30, 240, '3.0r/2.4e1r']
   end
 
   def test_parse_zero_denominator