Fix bugs when rounding to bignums

Also, since Emacs historically reported a range error when
rounding operations overflowed, do that consistently for all
bignum overflows.
* doc/lispref/errors.texi (Standard Errors):
* doc/lispref/numbers.texi (Integer Basics): Document range errors.
* src/alloc.c (range_error): Rename from integer_overflow.
All uses changed.
* src/floatfns.c (rounding_driver): When the result of a floating
point rounding operation does not fit into a fixnum, put it
into a bignum instead of always signaling an range error.
* test/src/floatfns-tests.el (divide-extreme-sign):
These tests now return the mathematically-correct answer
instead of signaling an error.
(bignum-round): Check that integers round to themselves.

2 files changed, 6 insertions, 4 deletions

diff --git a/doc/lispref/errors.texi b/doc/lispref/errors.texi
index a0e32c5631c..e61ea98e210 100644
--- a/doc/lispref/errors.texi
+++ b/doc/lispref/errors.texi
@@ -159,6 +159,11 @@ The message is @samp{No catch for tag}.  @xref{Catch and Throw}.
 The message is @samp{Attempt to modify a protected file}.
 @end ignore
 
+@item range-error
+The message is @code{Arithmetic range error}.
+This can happen with integers exceeding the @code{integer-width} limit.
+@xref{Integer Basics}.
+
 @item scan-error
 The message is @samp{Scan error}.  This happens when certain
 syntax-parsing functions find invalid syntax or mismatched
@@ -223,9 +228,6 @@ The message is @samp{Arithmetic domain error}.
 The message is @samp{Arithmetic overflow error}.  This is a subcategory
 of @code{domain-error}.
 
-@item range-error
-The message is @code{Arithmetic range error}.
-
 @item singularity-error
 The message is @samp{Arithmetic singularity error}.  This is a
 subcategory of @code{domain-error}.
diff --git a/doc/lispref/numbers.texi b/doc/lispref/numbers.texi
index a8150478613..d03113674f5 100644
--- a/doc/lispref/numbers.texi
+++ b/doc/lispref/numbers.texi
@@ -201,7 +201,7 @@ range are limited to absolute values less than
 @math{2^{n}},
 @end tex
 where @var{n} is this variable's value.  Attempts to create bignums outside
-this range result in an integer overflow error.  Setting this variable
+this range signal a range error.  Setting this variable
 to zero disables creation of bignums; setting it to a large number can
 cause Emacs to consume large quantities of memory if a computation
 creates huge integers.