7 files changed, 12 insertions, 13 deletions
diff --git a/array.c b/array.c
index b7be69afd6..172bf4914d 100644
--- a/array.c
+++ b/array.c
@@ -2823,7 +2823,7 @@ recursive_cmp(ary1, ary2, recur)
 
 /*
  *  call-seq:
- *     array <=> other_array   ->  -1, 0, +1
+ *     array <=> other_array   ->  -1, 0, +1 or nil
  *
  *  Comparison---Returns an integer (-1, 0,
  *  or +1) if this array is less than, equal to, or greater than
diff --git a/bignum.c b/bignum.c
index 473381b215..8f6c845ead 100644
--- a/bignum.c
+++ b/bignum.c
@@ -986,7 +986,7 @@ rb_big_to_f(x)
 
 /*
  *  call-seq:
- *     big <=> numeric   => -1, 0, +1
+ *     big <=> numeric   => -1, 0, +1 or nil
  *
  *  Comparison---Returns -1, 0, or +1 depending on whether <i>big</i> is
  *  less than, equal to, or greater than <i>numeric</i>. This is the
diff --git a/compar.c b/compar.c
index 8f3f83e40e..3903ec32d1 100644
--- a/compar.c
+++ b/compar.c
@@ -196,7 +196,9 @@ cmp_between(x, min, max)
  *  may be ordered. The class must define the <code><=></code> operator,
  *  which compares the receiver against another object, returning -1, 0,
  *  or +1 depending on whether the receiver is less than, equal to, or
- *  greater than the other object. <code>Comparable</code> uses
+ *  greater than the other object. If the other object is not comparable
+ *  then the <code><=></code> operator should return nil.
+ *  <code>Comparable</code> uses
  *  <code><=></code> to implement the conventional comparison operators
  *  (<code><</code>, <code><=</code>, <code>==</code>, <code>>=</code>,
  *  and <code>></code>) and the method <code>between?</code>.
diff --git a/file.c b/file.c
index 9e36a10386..53452526bd 100644
--- a/file.c
+++ b/file.c
@@ -187,7 +187,7 @@ get_stat(self)
 
 /*
  *  call-seq:
- *     stat <=> other_stat    => -1, 0, 1
+ *     stat <=> other_stat    => -1, 0, +1 or nil
  *
  *  Compares <code>File::Stat</code> objects by comparing their
  *  respective modification times.
diff --git a/numeric.c b/numeric.c
index 0936c6916f..957cf7b0e6 100644
--- a/numeric.c
+++ b/numeric.c
@@ -914,7 +914,7 @@ rb_dbl_cmp(a, b)
 
 /*
  *  call-seq:
- *     flt <=> numeric   => -1, 0, +1
+ *     flt <=> numeric   => -1, 0, +1 or nil
  *
  *  Returns -1, 0, or +1 depending on whether <i>flt</i> is less than,
  *  equal to, or greater than <i>numeric</i>. This is the basis for the
@@ -2423,7 +2423,7 @@ fix_equal(x, y)
 
 /*
  *  call-seq:
- *     fix <=> numeric    => -1, 0, +1
+ *     fix <=> numeric    => -1, 0, +1 or nil
  *
  *  Comparison---Returns -1, 0, or +1 depending on whether <i>fix</i> is
  *  less than, equal to, or greater than <i>numeric</i>. This is the
diff --git a/string.c b/string.c
index fe7516892b..924b5e3c92 100644
--- a/string.c
+++ b/string.c
@@ -1031,7 +1031,7 @@ rb_str_eql(str1, str2)
 
 /*
  *  call-seq:
- *     str <=> other_str   => -1, 0, +1
+ *     str <=> other_str   => -1, 0, +1 or nil
  *
  *  Comparison---Returns -1 if <i>other_str</i> is greater than, 0 if
  *  <i>other_str</i> is equal to, and +1 if <i>other_str</i> is less than
@@ -1085,7 +1085,7 @@ rb_str_cmp_m(str1, str2)
 
 /*
  *  call-seq:
- *     str.casecmp(other_str)   => -1, 0, +1
+ *     str.casecmp(other_str)   => -1, 0, +1 or nil
  *
  *  Case-insensitive version of <code>String#<=></code>.
  *
diff --git a/time.c b/time.c
index df43e2339a..6fe5326dda 100644
--- a/time.c
+++ b/time.c
@@ -950,12 +950,9 @@ time_usec(time)
 
 /*
  *  call-seq:
- *     time <=> other_time => -1, 0, +1
- *     time <=> numeric    => -1, 0, +1
+ *     time <=> other_time => -1, 0, +1 or nil
  *
- *  Comparison---Compares <i>time</i> with <i>other_time</i> or with
- *  <i>numeric</i>, which is the number of seconds (possibly
- *  fractional) since epoch.
+ *  Comparison---Compares <i>time</i> with <i>other_time</i>.
  *
  *     t = Time.now       #=> Wed Apr 09 08:56:03 CDT 2003
  *     t2 = t + 2592000   #=> Fri May 09 08:56:03 CDT 2003