Re: Merging bignum to master

[Paul Eggert <eggert@cs.ucla.edu>]

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Pip Cet wrote:

> I notice that there are a few places where you use XFIXNUMPTR
> directly, rather than make_mint_ptr. Is that intentional? I think now
> would be a good time to fix it and make XFIXNUMPTR internal to lisp.h.

It's intentional since those few places don't need the full power of 
make_mint_ptr (often the pointers are already aligned) and there might be 
trouble if storage allocation fails if the pointer is not aligned. Perhaps 
you're right and this is overkill; it is confusing at any rate. In the meantime 
I installed the attached first patch to fix a glitch I saw in this area while 
looking at the current XFIXNUMPTR uses.

> Also, the doc comments for most_negative_fixnum and
> most_positive_fixnum in data.c still need updating.

Thanks, done in the second attached patch.

[-- Attachment #2: 0001-Fix-check-for-unsafe-watch-descriptor.patch --]
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From 76101698a770d389f22b547c331ec78473040c47 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Mon, 13 Aug 2018 15:45:17 -0700
Subject: [PATCH 1/2] Fix check for unsafe watch descriptor

* src/lisp.h (make_pointer_integer_unsafe): New function.
(make_pointer_integer): Use it.
* src/gfilenotify.c (dir_monitor_callback): Omit redundant eassert.
(Fgfile_add_watch): Signal an error instead of failing an
assertion if the pointer does not work.
---
 src/gfilenotify.c | 7 +++----
 src/lisp.h        | 8 +++++++-
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/src/gfilenotify.c b/src/gfilenotify.c
index 7eea2cfac1..798f308b31 100644
--- a/src/gfilenotify.c
+++ b/src/gfilenotify.c
@@ -77,7 +77,6 @@ dir_monitor_callback (GFileMonitor *monitor,
 
   /* Determine callback function.  */
   monitor_object = make_pointer_integer (monitor);
-  eassert (FIXNUMP (monitor_object));
   watch_object = assq_no_quit (monitor_object, watch_list);
 
   if (CONSP (watch_object))
@@ -203,10 +202,10 @@ will be reported only in case of the `moved' event.  */)
   if (! monitor)
     xsignal2 (Qfile_notify_error, build_string ("Cannot watch file"), file);
 
-  Lisp_Object watch_descriptor = make_pointer_integer (monitor);
+  Lisp_Object watch_descriptor = make_pointer_integer_unsafe (monitor);
 
-  /* Check the dicey assumption that make_pointer_integer is safe.  */
-  if (! FIXNUMP (watch_descriptor))
+  if (! (FIXNUMP (watch_descriptor)
+	 && XFIXNUMPTR (watch_descriptor) == monitor))
     {
       g_object_unref (monitor);
       xsignal2 (Qfile_notify_error, build_string ("Unsupported file watcher"),
diff --git a/src/lisp.h b/src/lisp.h
index b7ef8dc63a..18d53537cc 100644
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -1188,10 +1188,16 @@ XFIXNUMPTR (Lisp_Object a)
   return XUNTAG (a, Lisp_Int0, char);
 }
 
+INLINE Lisp_Object
+make_pointer_integer_unsafe (void *p)
+{
+  return TAG_PTR (Lisp_Int0, p);
+}
+
 INLINE Lisp_Object
 make_pointer_integer (void *p)
 {
-  Lisp_Object a = TAG_PTR (Lisp_Int0, p);
+  Lisp_Object a = make_pointer_integer_unsafe (p);
   eassert (FIXNUMP (a) && XFIXNUMPTR (a) == p);
   return a;
 }
-- 
2.17.1


[-- Attachment #3: 0002-Update-doc-strings-for-fixnum-constants.patch --]
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From dc18a0917a5531ef3e1c9b4921bb4d8f317bc7a4 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Mon, 13 Aug 2018 15:55:06 -0700
Subject: [PATCH 2/2] Update doc strings for fixnum constants

* src/data.c (most-positive-fixnum, most-negative-fixnum):
Update doc strings in the light of fixnums.
---
 src/data.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/data.c b/src/data.c
index 7b8dd45c94..a1215b9d6b 100644
--- a/src/data.c
+++ b/src/data.c
@@ -4260,13 +4260,13 @@ syms_of_data (void)
   set_symbol_function (Qwholenump, XSYMBOL (Qnatnump)->u.s.function);
 
   DEFVAR_LISP ("most-positive-fixnum", Vmost_positive_fixnum,
-	       doc: /* The largest value that is representable in a Lisp integer.
+	       doc: /* The greatest integer that is represented efficiently.
 This variable cannot be set; trying to do so will signal an error.  */);
   Vmost_positive_fixnum = make_fixnum (MOST_POSITIVE_FIXNUM);
   make_symbol_constant (intern_c_string ("most-positive-fixnum"));
 
   DEFVAR_LISP ("most-negative-fixnum", Vmost_negative_fixnum,
-	       doc: /* The smallest value that is representable in a Lisp integer.
+	       doc: /* The least integer that is represented efficiently.
 This variable cannot be set; trying to do so will signal an error.  */);
   Vmost_negative_fixnum = make_fixnum (MOST_NEGATIVE_FIXNUM);
   make_symbol_constant (intern_c_string ("most-negative-fixnum"));
-- 
2.17.1