How to compile C++ code using modules-ts and gcc (experimental)?

6
votes

I've been trying to code something using the new experimental feature "modules-ts" that will be included in c++20. I've cloned the gcc branch (found here: https://gcc.gnu.org/wiki/cxx-modules), and I'm trying to follow that tutorial (on the link) using modules-ts but an g++ error is preventing me from doing that:

g++: error: unrecognized command-line option ‘-fmodules-ts’

I tried to see the version of g++, to make sure that is not reading from another previous version. And the answer is:

g++ (GCC) 10.0.0 20191029 (experimental) Copyright (C) 2019 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Here is the command that I'm trying to run:

g++ -fmodules-ts hello.cppm main.cpp

1
gccg++

1 Answers

5
votes

Modules-ts is not merged into GCC's main branch yet. You need to download GCC's source and compile it yourself, for further instructions see GCC's installation guide. Grab the source using 

svn co svn://gcc.gnu.org/svn/gcc/branches/c++-modules SomeLocalDir

instead of 

svn checkout svn://gcc.gnu.org/svn/gcc/trunk SomeLocalDir

and you'll get the correct version.

EDIT: For clarification, in this answer I assumed the OP did not compile the right GCC version because there is no svn revision number inside his gcc --version.