[docs] added a note about g++ versions for macOS users (#1380)

* added a note about g++ versions for macOS users

* hotfix excess dot in FAQ

* added notes about gcc version in installation guides

R-package/README.md

@@ -33,7 +33,7 @@ Install LightGBM R-package with the following command:
 ```sh
 git clone --recursive https://github.com/Microsoft/LightGBM
 cd LightGBM/R-package
-# export CXX=g++-7 CC=gcc-7 # for macOS
+# export CXX=g++-7 CC=gcc-7  # for macOS (replace 7 with version of gcc installed on your machine)
 R CMD INSTALL --build . --no-multiarch
 ```
 
@@ -43,7 +43,7 @@ Or build a self-contained R package which can be installed afterwards:
 git clone --recursive https://github.com/Microsoft/LightGBM
 cd LightGBM/R-package
 Rscript build_package.R
-# export CXX=g++-7 CC=gcc-7 # for macOS
+# export CXX=g++-7 CC=gcc-7  # for macOS (replace 7 with version of gcc installed on your machine)
 R CMD INSTALL lightgbm_2.1.0.tar.gz --no-multiarch
 ``` 
 

docs/FAQ.rst

@@ -111,7 +111,7 @@ LightGBM
 
 -  **Solution 9**: Probably you're trying to pass via ``categorical_feature`` parameter a column with very large values. For instance, it can be some IDs.
    In LightGBM categorical features are limited by int32 range, so you cannot pass values that are greater than ``Int32.MaxValue`` (2147483647) as categorical features
-   (see `Microsoft/LightGBM#1359 <https://github.com/Microsoft/LightGBM/issues/1359>`__.). You should convert them into integer range from zero to number of categories first.
+   (see `Microsoft/LightGBM#1359 <https://github.com/Microsoft/LightGBM/issues/1359>`__). You should convert them into integer range from zero to number of categories first.
 
 --------------
 

docs/Installation-Guide.rst

@@ -101,7 +101,7 @@ Then install LightGBM:
 .. code::
 
   git clone --recursive https://github.com/Microsoft/LightGBM ; cd LightGBM
-  export CXX=g++-7 CC=gcc-7
+  export CXX=g++-7 CC=gcc-7  # replace 7 with version of gcc installed on your machine
   mkdir build ; cd build
   cmake ..
   make -j4
@@ -194,7 +194,7 @@ Then run the following commands:
 .. code::
 
   git clone --recursive https://github.com/Microsoft/LightGBM ; cd LightGBM
-  export CXX=g++-7 CC=gcc-7
+  export CXX=g++-7 CC=gcc-7  # replace 7 with version of gcc installed on your machine
   mkdir build ; cd build
   cmake -DUSE_MPI=ON ..
   make -j4
@@ -342,7 +342,7 @@ Then install LightGBM:
 .. code::
 
   git clone --recursive https://github.com/Microsoft/LightGBM ; cd LightGBM
-  export CXX=g++-7 CC=gcc-7
+  export CXX=g++-7 CC=gcc-7  # replace 7 with version of gcc installed on your machine
   mkdir build ; cd build
   cmake -DUSE_HDFS=ON ..
   make -j4

python-package/README.rst

@@ -17,8 +17,11 @@ Note: 32-bit Python is not supported. Please install 64-bit version.
 
 Install from `PyPI <https://pypi.org/project/lightgbm>`_ Using ``pip``
 ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
 For Windows users, `VC runtime <https://go.microsoft.com/fwlink/?LinkId=746572>`_ is needed if Visual Studio (2015 or 2017) is not installed.
 
+For macOS users, latest versions of LightGBM are built with **g++-8** and cannot be launched on systems with **g++-7** and earlier. You should update your **g++** compiler if you don't want to build from sources or install LightGBM 2.1.1 which is the last version built with **g++-7**.
+
 Install `wheel <http://pythonwheels.com>`_ via ``pip install wheel`` first. After that download the wheel file and install from it:
 
 .. code:: sh
@@ -34,7 +37,7 @@ Build from Sources
 
 For Linux and macOS users, installation from sources requires installed `CMake <https://cmake.org/>`_.
 
-For macOS users, you need to specify compilers by runnig ``export CXX=g++-7 CC=gcc-7`` first.
+For macOS users, you need to specify compilers by runnig ``export CXX=g++-7 CC=gcc-7`` (replace 7 with version of gcc installed on your machine) first.
 
 For Windows users, Visual Studio (or `MS Build <https://www.visualstudio.com/downloads/>`_) is needed. If you get any errors during installation, you may need to install `CMake <https://cmake.org/>`_ (version 3.8 or higher).
 
@@ -111,7 +114,7 @@ For Windows users, Visual Studio (or `MS Build <https://www.visualstudio.com/dow
 
     git clone --recursive https://github.com/Microsoft/LightGBM.git
     cd LightGBM/python-package
-    # export CXX=g++-7 CC=gcc-7  # for macOS users only
+    # export CXX=g++-7 CC=gcc-7  # for macOS users only (replace 7 with version of gcc installed on your machine)
     python setup.py install
 
 Note: ``sudo`` (or administrator rights in Windows) may be needed to perform the command.