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Re: Troubles with conditional adding files to library
From: |
Russ Allbery |
Subject: |
Re: Troubles with conditional adding files to library |
Date: |
Fri, 27 Mar 2009 08:23:16 -0700 |
User-agent: |
Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux) |
"Gerald I. Evenden" <address@hidden> writes:
> I use both functions quite frequently but do nothing special about
> library use or using alternate source. I just assumed they are part of
> the standard library. I do not understand why there is anything special
> about these routines and did wonder why the special attention was given
> them in the configure.scan.
AC_FUNC_MALLOC exists because of:
If the `malloc' function is compatible with the GNU C library
`malloc' (i.e., `malloc (0)' returns a valid pointer), define
`HAVE_MALLOC' to 1. Otherwise define `HAVE_MALLOC' to 0, ask for
an `AC_LIBOBJ' replacement for `malloc', and define `malloc' to
`rpl_malloc' so that the native `malloc' is not used in the main
project.
If you don't rely on malloc(0) working, you don't care. I never rely on
that; I think it's bad coding style.
AC_FUNC_STRTOD exists because of:
/* Some versions of Linux strtod mis-parse strings with leading '+'. */
char *string = " +69";
char *term;
double value;
value = strtod (string, &term);
if (value != 69 || term != (string + 4))
return 1;
and:
/* Under Solaris 2.4, strtod returns the wrong value for the
terminating character under some conditions. */
char *string = "NaN";
char *term;
strtod (string, &term);
if (term != string && *(term - 1) == 0)
return 1;
If your uses of strtod don't care, you probably don't care about this one
either.
The Autoconf manual has the documentation for both of these.
--
Russ Allbery (address@hidden) <http://www.eyrie.org/~eagle/>
Re: Troubles with conditional adding files to library, Jan Engelhardt, 2009/03/27