2 dnl Copyright (C) 2002-2003, 2006-2017 Free Software Foundation, Inc.
3 dnl This file is free software; the Free Software Foundation
4 dnl gives unlimited permission to copy and/or distribute it,
5 dnl with or without modifications, as long as this notice is preserved.
7 AC_DEFUN([gl_FUNC_STRTOD],
9 AC_REQUIRE([gl_STDLIB_H_DEFAULTS])
10 m4_ifdef([gl_FUNC_STRTOD_OBSOLETE], [
11 dnl Test whether strtod is declared.
12 dnl Don't call AC_FUNC_STRTOD, because it does not have the right guess
13 dnl when cross-compiling.
14 dnl Don't call AC_CHECK_FUNCS([strtod]) because it would collide with the
15 dnl ac_cv_func_strtod variable set by the AC_FUNC_STRTOD macro.
16 AC_CHECK_DECLS_ONCE([strtod])
17 if test $ac_cv_have_decl_strtod != yes; then
21 if test $HAVE_STRTOD = 1; then
22 AC_CACHE_CHECK([whether strtod obeys C99], [gl_cv_func_strtod_works],
23 [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
27 /* Compare two numbers with ==.
28 This is a separate function because IRIX 6.5 "cc -O" miscompiles an
31 numeric_equal (double x, double y)
38 /* In some old versions of Linux (2000 or before), strtod mis-parses
39 strings with leading '+'. */
40 const char *string = " +69";
42 double value = strtod (string, &term);
43 if (value != 69 || term != (string + 4))
47 /* Under Solaris 2.4, strtod returns the wrong value for the
48 terminating character under some conditions. */
49 const char *string = "NaN";
51 strtod (string, &term);
52 if (term != string && *(term - 1) == 0)
56 /* Older glibc and Cygwin mis-parse "-0x". */
57 const char *string = "-0x";
59 double value = strtod (string, &term);
61 if (1.0 / value != -1.0 / zero || term != (string + 2))
65 /* Many platforms do not parse hex floats. */
66 const char *string = "0XaP+1";
68 double value = strtod (string, &term);
69 if (value != 20.0 || term != (string + 6))
73 /* Many platforms do not parse infinities. HP-UX 11.31 parses inf,
74 but mistakenly sets errno. */
75 const char *string = "inf";
79 value = strtod (string, &term);
80 if (value != HUGE_VAL || term != (string + 3) || errno)
84 /* glibc 2.7 and cygwin 1.5.24 misparse "nan()". */
85 const char *string = "nan()";
87 double value = strtod (string, &term);
88 if (numeric_equal (value, value) || term != (string + 5))
92 /* darwin 10.6.1 misparses "nan(". */
93 const char *string = "nan(";
95 double value = strtod (string, &term);
96 if (numeric_equal (value, value) || term != (string + 3))
101 [gl_cv_func_strtod_works=yes],
102 [gl_cv_func_strtod_works=no],
103 [dnl The last known bugs in glibc strtod(), as of this writing,
104 dnl were fixed in version 2.8
105 AC_EGREP_CPP([Lucky user],
107 #include <features.h>
108 #ifdef __GNU_LIBRARY__
109 #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ >= 8) || (__GLIBC__ > 2)) \
110 && !defined __UCLIBC__
115 [gl_cv_func_strtod_works="guessing yes"],
116 [gl_cv_func_strtod_works="guessing no"])])])
117 case "$gl_cv_func_strtod_works" in
126 # Prerequisites of lib/strtod.c.
127 AC_DEFUN([gl_PREREQ_STRTOD], [
128 AC_REQUIRE([gl_CHECK_LDEXP_NO_LIBM])
129 if test $gl_cv_func_ldexp_no_libm = yes; then
130 AC_DEFINE([HAVE_LDEXP_IN_LIBC], [1],
131 [Define if the ldexp function is available in libc.])