Mercurial > gnulib
view m4/strtod.m4 @ 13456:fd291325b6d5
strtod: make it more-accurate typically, and don't require libm
* lib/strtod.c (_GL_ARG_NONNULL): Remove; no longer needed.
Include limits.h. Don't include string.h.
(HAVE_LDEXP_IN_LIBC, HAVE_RAW_DECL_STRTOD): Define to 0 if not defined.
(locale_isspace): New function, so that no casts are needed to
check whether *s is a space.
(ldexp): Provide an unused dummy if not available.
(scale_radix_exp, parse_number, underlying_strtod): New functions.
(strtod): Use them. This implementation prefers to use the
underlying strtod if available, falling back on our own code
only to fix known bugs. This is more likely to produce an
accurate result. Also, it avoids the use of libm functions.
* m4/strtod.m4 (gl_FUNC_STRTOD): Don't invoke _AC_LIBOBJ_STRTOD;
no longer needed. Invoke AC_LIBOBJ([strtod]); don't know why this
was absent, but it caused a test failure with coreutils.
(gl_PREREQ_STRTOD): Check wither ldexp can be used without linking
with libm.
* modules/strtod (Makefile.am, Link): libm is no longer needed.
* modules/strtod-tests (Makefile.am): Likewise.
author | Paul R. Eggert <eggert@cs.ucla.edu> |
---|---|
date | Mon, 12 Jul 2010 09:14:10 -0700 |
parents | 727e17a1e8b3 |
children | 88292c519d86 |
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# strtod.m4 serial 15 dnl Copyright (C) 2002-2003, 2006-2010 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, dnl with or without modifications, as long as this notice is preserved. AC_DEFUN([gl_FUNC_STRTOD], [ AC_REQUIRE([gl_STDLIB_H_DEFAULTS]) dnl Test whether strtod is declared. dnl Don't call AC_FUNC_STRTOD, because it does not have the right guess dnl when cross-compiling. dnl Don't call AC_CHECK_FUNCS([strtod]) because it would collide with the dnl ac_cv_func_strtod variable set by the AC_FUNC_STRTOD macro. AC_CHECK_DECLS_ONCE([strtod]) if test $ac_cv_have_decl_strtod != yes; then HAVE_STRTOD=0 else AC_CACHE_CHECK([whether strtod obeys C99], [gl_cv_func_strtod_works], [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ #include <stdlib.h> #include <math.h> #include <errno.h> /* Compare two numbers with ==. This is a separate function because IRIX 6.5 "cc -O" miscompiles an 'x == x' test. */ static int numeric_equal (double x, double y) { return x == y; } ]], [[ { /* In some old versions of Linux (2000 or before), strtod mis-parses strings with leading '+'. */ const char *string = " +69"; char *term; double value = strtod (string, &term); if (value != 69 || term != (string + 4)) return 1; } { /* Under Solaris 2.4, strtod returns the wrong value for the terminating character under some conditions. */ const char *string = "NaN"; char *term; strtod (string, &term); if (term != string && *(term - 1) == 0) return 1; } { /* Older glibc and Cygwin mis-parse "-0x". */ const char *string = "-0x"; char *term; double value = strtod (string, &term); double zero = 0.0; if (1.0 / value != -1.0 / zero || term != (string + 2)) return 1; } { /* Many platforms do not parse hex floats. */ const char *string = "0XaP+1"; char *term; double value = strtod (string, &term); if (value != 20.0 || term != (string + 6)) return 1; } { /* Many platforms do not parse infinities. HP-UX 11.31 parses inf, but mistakenly sets errno. */ const char *string = "inf"; char *term; double value; errno = 0; value = strtod (string, &term); if (value != HUGE_VAL || term != (string + 3) || errno) return 1; } { /* glibc 2.7 and cygwin 1.5.24 misparse "nan()". */ const char *string = "nan()"; char *term; double value = strtod (string, &term); if (numeric_equal (value, value) || term != (string + 5)) return 1; } { /* darwin 10.6.1 misparses "nan(". */ const char *string = "nan("; char *term; double value = strtod (string, &term); if (numeric_equal (value, value) || term != (string + 3)) return 1; } ]])], [gl_cv_func_strtod_works=yes], [gl_cv_func_strtod_works=no], [dnl The last known bugs in glibc strtod(), as of this writing, dnl were fixed in version 2.8 AC_EGREP_CPP([Lucky user], [ #include <features.h> #ifdef __GNU_LIBRARY__ #if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 8) || (__GLIBC__ > 2) Lucky user #endif #endif ], [gl_cv_func_strtod_works=yes], [gl_cv_func_strtod_works="guessing no"])])]) if test "$gl_cv_func_strtod_works" != yes; then REPLACE_STRTOD=1 fi fi if test $HAVE_STRTOD = 0 || test $REPLACE_STRTOD = 1; then AC_LIBOBJ([strtod]) gl_PREREQ_STRTOD fi ]) # Prerequisites of lib/strtod.c. # FIXME: This implementation is a copy of printf-frexp.m4 and should be shared. AC_DEFUN([gl_PREREQ_STRTOD], [ AC_CACHE_CHECK([whether ldexp can be used without linking with libm], [gl_cv_func_ldexp_no_libm], [ AC_TRY_LINK([#include <math.h> double x; int y;], [return ldexp (x, y) < 1;], [gl_cv_func_ldexp_no_libm=yes], [gl_cv_func_ldexp_no_libm=no]) ]) if test $gl_cv_func_ldexp_no_libm = yes; then AC_DEFINE([HAVE_LDEXP_IN_LIBC], [1], [Define if the ldexp function is available in libc.]) fi ])