Re: ptrdiff_t overflow checks for malloc-posix etc.

[Bruno Haible]

> * doc/posix-functions/calloc.texi:
> * doc/posix-functions/malloc.texi:
> * doc/posix-functions/realloc.texi:
> Mention ptrdiff_t issues, and go into more detail about what
> the gnu extension module does.

The patch dropped the list of affected platforms. However this list is
important so that
  - users can decide whether they want to pull in the module,
  - I know on which platforms to conduct tests when preparing changes in this
    area.


2021-04-18  Bruno Haible  <br...@clisp.org>

        malloc-posix, realloc-posix, calloc-posix: Document affected platforms.
        * doc/posix-functions/malloc.texi: Re-add platforms list.
        * doc/posix-functions/realloc.texi: Likewise.
        * doc/posix-functions/calloc.texi: Likewise.

diff --git a/doc/posix-functions/calloc.texi b/doc/posix-functions/calloc.texi
index 9ba40c0..57bec4d 100644
--- a/doc/posix-functions/calloc.texi
+++ b/doc/posix-functions/calloc.texi
@@ -28,6 +28,7 @@ It fixes this portability problem:
 
 @itemize
 @item
-On some platforms, @code{calloc (0, s)} and @code{calloc (n, 0)}
-return @code{NULL} on success.
+@code{calloc (0, s)} and @code{calloc (n, 0)} return @code{NULL} on success
+on some platforms:
+AIX 7.2.
 @end itemize
diff --git a/doc/posix-functions/malloc.texi b/doc/posix-functions/malloc.texi
index 8295173..028f1dc 100644
--- a/doc/posix-functions/malloc.texi
+++ b/doc/posix-functions/malloc.texi
@@ -26,5 +26,6 @@ by fixing this portability problem:
 
 @itemize
 @item
-On some platforms, @code{malloc (0)} returns @code{NULL} on success.
+@code{malloc (0)} returns @code{NULL} on success on some platforms:
+AIX 7.2.
 @end itemize
diff --git a/doc/posix-functions/realloc.texi b/doc/posix-functions/realloc.texi
index 282e360..009bdab 100644
--- a/doc/posix-functions/realloc.texi
+++ b/doc/posix-functions/realloc.texi
@@ -39,7 +39,8 @@ It fixes these portability problems:
 
 @itemize
 @item
-On some platforms, @code{realloc (NULL, 0)} returns @code{NULL} on success.
+@code{realloc (NULL, 0)} returns @code{NULL} on success on some platforms:
+AIX 7.2.
 
 @item
 On some platforms, @code{realloc (p, 0)} with non-null @code{p}