error: fmod is not a member of std

[dima4p]

Hello, while installing the gem I've got the problem to compile the extension.

$ gem install sassc -v '2.2.0' --source 'https://rubygems.org/'                     Building native extensions. This could take a while...
ERROR:  Error installing sassc:
        ERROR: Failed to build gem native extension.

    current directory: /usr/local/rvm/gems/ruby-2.6.3@my_project/gems/sassc-2.2.0/ext
/usr/local/rvm/rubies/ruby-2.6.3/bin/ruby -I /usr/local/rvm/rubies/ruby-2.6.3/lib/ruby/2.6.0 -r ./siteconf20190828-18319-ou8ovf.rb extconf.rb
creating Makefile

current directory: /usr/local/rvm/gems/ruby-2.6.3@my_project/gems/sassc-2.2.0/ext
make "DESTDIR=" clean

current directory: /usr/local/rvm/gems/ruby-2.6.3@my_project/gems/sassc-2.2.0/ext
make "DESTDIR="
compiling ./libsass/src/color_maps.cpp
In file included from ./libsass/src/ast.hpp:19:0,
                 from ./libsass/src/color_maps.cpp:5:
./libsass/src/util.hpp: In function ‘T Sass::absmod(const T&, const T&)’:
./libsass/src/util.hpp:28:11: error: ‘fmod’ is not a member of ‘std’
     T m = std::fmod(n, r);
           ^
./libsass/src/util.hpp:28:11: note: suggested alternative:
In file included from /usr/include/features.h:368:0,
                 from /usr/include/c++/5.5.0/x86_64-slackware-linux/bits/os_defines.h:39,
                 from /usr/include/c++/5.5.0/x86_64-slackware-linux/bits/c++config.h:489,
                 from /usr/include/c++/5.5.0/string:38,
                 from ./libsass/src/sass.hpp:55,
                 from ./libsass/src/color_maps.cpp:3:
/usr/include/bits/mathcalls.h:187:1: note:   ‘fmod’
 __MATHCALL (fmod,, (_Mdouble_ __x, _Mdouble_ __y));
 ^
Makefile:235: recipe for target 'color_maps.o' failed
make: *** [color_maps.o] Error 1

My gcc is:

$ gcc -v
Reading specs from /usr/lib64/gcc/x86_64-slackware-linux/5.5.0/specs
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-slackware-linux/5.5.0/lto-wrapper
Target: x86_64-slackware-linux
Configured with: ../gcc-5.5.0/configure --prefix=/usr --libdir=/usr/lib64 --mandir=/usr/man --infodir=/usr/info --enable-shared --enable-bootstrap --enable-languages=ada,c,c++,fortran,go,java,lto,objc --enable-threads=posix --enable-checking=release --enable-objc-gc --with-system-zlib --with-python-dir=/lib64/python2.7/site-packages --enable-libstdcxx-dual-abi --with-default-libstdcxx-abi=gcc4-compatible --disable-libunwind-exceptions --enable-__cxa_atexit --enable-libssp --enable-lto --disable-install-libiberty --with-gnu-ld --verbose --enable-java-home --with-java-home=/usr/lib64/jvm/jre --with-jvm-root-dir=/usr/lib64/jvm --with-jvm-jar-dir=/usr/lib64/jvm/jvm-exports --with-arch-directory=amd64 --with-antlr-jar=/home/slackware/slackbuilds/gcc-5.5.0/antlr-runtime-3.4.jar --enable-multilib --target=x86_64-slackware-linux --build=x86_64-slackware-linux --host=x86_64-slackware-linux
Thread model: posix
gcc version 5.5.0 (GCC) 

With the version 2.1.0 there is no problem

[glebm]

Version 2.1.0 comes with a pre-compiled library for Linux+glibc but the new version doesn't.

This seems to be a bug (missing include) that's been fixed on libsass master but is not in any release yet. This missing include seems to only break some compiler versions.

[dima4p]

@glebm, so it seems to be easy fixable?

[RaymondFallon]

Hey @glebm, thanks for identifying the problem! Is there any way to estimate when this fix will be included in a new release?

[dima4p]

@RaymondFallon, is not it easier to fix the line

./libsass/src/util.hpp:28:11

?

[taca]

Bellow code might help.

--- ext/libsass/src/util.hpp.orig	2019-09-16 15:47:08.475272400 +0000
+++ ext/libsass/src/util.hpp
@@ -9,6 +9,7 @@
 #include "ast_fwd_decl.hpp"
 
 #include <cstring>
+#include <cmath>
 #include <vector>
 #include <string>
 #include <assert.h>

[vmiheer]

#153 is dupe of this.
Someone maybe need to update the libsass submodule? So that cmath would be included as per @taca's suggestion?

[ahorek]

update the libsass submodule? see #164

[vmiheer]

@ahorek, yup that release has include. So potentially fix the issue.

[vmiheer]

I built the gem with the modification and used as part of jekyll, things work without hitch.

[dima4p]

The problem for me was the version of GCC compiler.
After I have upgraded it from 5.5.0 to 9.2.0 all is OK.
Probably gem should check the version and report it at install.

[JuPlutonic]

After upgrade of GCC from 5.5.0 to 8.3.0 the installation process successfully finished:
Installing sassc 2.2.1 (was 2.1.0) with native extensions🛠
Upd. just brew unlink gcc

[vmiheer]

Note: upgrading compiler isn't always solution e.g. linuxbrew uses gcc 5.5.

[rscircus]

brew uninstall --ignore-dependencies gcc solved it for me.

Be aware that you should know what you are doing and have replacements available. Like sudo apt-get install ruby-full build-essential zlib1g-dev or something similar. Else the other apps brew installed might stop working for you.