Bug #74039 [Com]: is_infinite(-INF) returns false

Edit report at https://bugs.php.net/bug.php?id=74039&edit=1 ID: 74039 Comment by: bug at example dot com Reported by: bugs dot php dot net at chsc dot dk Summary: is_infinite(-INF) returns false Status: Closed Type: Bug Package: Math related Operating System: Alpine Linux PHP Version: 7.0.15 Assigned To: nikic Block user comment: N Private report: N New Comment: $ man isfinite says that isfinite() is a C99 feature. In order to see what's going on compiler diagnostics helps (please note that the return type of main is int according to all known standards): main.c ------ #include <stdio.h> #include <math.h> int main() { double d = 0; printf ("%d\n", isfinite (d)); return 0; } ------ $ gcc -Wall -Werror main.c cc1: warnings being treated as errors main.c: In function 'main': main.c:7: error: implicit declaration of function 'isfinite' The default mode of GCC is C99 since GCC 5, before it was C89. For those older compilers you have to explitly switch C99-mode on: $ gcc -Wall -Werror -std=c99 main.c The reason why there is an linker error is that for the implicitly declared isfinite() the symbol is the object file and the symbol used in the libc is not "isfinite" but here on my machine "__finite": $ nm main.o U __finite 0000000000000000 T main U printf Previous Comments: ------------------------------------------------------------------------ [2017-03-20 12:48:39] georgi at unixsol dot org The C example code does not compile on CentOS 5: georgi@cent5:~$ cat > z.c #include <math.h> #ifndef isfinite # error Not defined #endif void main() {} georgi@cent5:~$ gcc z.c z.c:3:3: error: #error Not defined z.c: In function ‘main’: z.c:5: warning: return type of ‘main’ is not ‘int’ georgi@cent5:~$ rpm -qa | grep glibc | sort | uniq glibc-2.5-58.el5_6.3 glibc-common-2.5-58.el5_6.3 glibc-devel-2.5-58.el5_6.3 glibc-headers-2.5-58.el5_6.3 ------------------------------------------------------------------------ [2017-03-17 19:12:35] nikic@php.net CentOS issue also reported in bug #74265. ------------------------------------------------------------------------ [2017-03-17 16:50:40] nikic@php.net Does #include <math.h> #ifndef isfinite # error Not defined #endif void main() {} compile for you? This seems pretty weird, because glibc should have isfinite(). ------------------------------------------------------------------------ [2017-03-17 16:32:12] georgi at unixsol dot org The fix in https://github.com/php/php-src/commit/714d825b62e719447686da6efe3b4063c2f25749 breaks the build for me for PHP 7.1.3 and PHP 7.0.17 branches: The build fails with: ext/filter/.libs/logical_filters.o: In function `php_filter_float': /home/georgi/build/BUILD/php71-7.1.3/src/ext/filter/logical_filters.c:411: undefined reference to `isfinite' ext/intl/collator/.libs/collator_is_numeric.o: In function `collator_is_numeric': /home/georgi/build/BUILD/php71-7.1.3/src/ext/intl/collator/collator_is_numeric.c:255: undefined reference to `isfinite' ext/standard/.libs/math.o: In function `zif_is_finite': /home/georgi/build/BUILD/php71-7.1.3/src/ext/standard/math.c:589: undefined reference to `isfinite' ext/standard/.libs/math.o: In function `_php_math_round': /home/georgi/build/BUILD/php71-7.1.3/src/ext/standard/math.c:133: undefined reference to `isfinite' /home/georgi/build/BUILD/php71-7.1.3/src/ext/standard/math.c:201: undefined reference to `isfinite' ext/standard/.libs/var.o:/home/georgi/build/BUILD/php71-7.1.3/src/ext/standard/var.c:473: more undefined references to `isfinite' follow After reverting 714d825b62e719447686da6efe3b4063c2f25749, I can build both 7.0 and 7.1 as before. I can provide any logs necessary to track the problem. The build machine is CentOS 5.5 with glibc-devel-2.5-58.el5_6.3. ------------------------------------------------------------------------ [2017-02-05 17:15:44] nikic@php.net Fixed by https://github.com/php/php-src/commit/9ea0949f43959ff0cf519e7a10ef9de7a538cde3. ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at https://bugs.php.net/bug.php?id=74039 -- Edit this bug report at https://bugs.php.net/bug.php?id=74039&edit=1