fix filesystem compilation

Author: Lishen1

.travis.yml

@@ -6,6 +6,8 @@
 #   - master
 
 dist: bionic
+osx_image: xcode11.6
+
 language: cpp
 os:
     - linux
@@ -16,6 +18,10 @@ compiler:
 
 addons:
   apt:
+    sources:
+    - sourceline: 'deb http://apt.llvm.org/bionic/ llvm-toolchain-bionic-9 main'
+      key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
+    - sourceline: 'ppa:ubuntu-toolchain-r/test'
     packages:
         - libxrandr-dev
         - libxinerama-dev
@@ -24,6 +30,16 @@ addons:
         - libglu1-mesa-dev
         - freeglut3-dev
         - mesa-common-dev
+        - clang-9
+        - gcc-9
+        - g++-9
+  homebrew:
+    packages:
+    # - cmake
+    # - gcc@9
+    - llvm@10
+    # - ninja
+    update: true
 
 jobs:
   # include:
@@ -41,11 +57,34 @@ jobs:
         env: TARGET_CPU=x86 BUILD_CONFIGURATION=Release
 
 # before_install:
+    # - sudo add-apt-repository ppa:jonathonf/gcc -y
+    # - sudo apt-get install gcc-9 -y
 #   - sudo apt install libxrandr-dev -y
 install:
     # скрипт настройки среды и установки зависимостей:
     - source travis/install-$TRAVIS_OS_NAME.sh
 
+    # The following Homebrew packages aren't linked by default, and need to be
+    # prepended to the path explicitly.
+    - if [ "$TRAVIS_OS_NAME" = "osx" ]; then
+        export PATH="$(brew --prefix llvm)/bin:$PATH";
+      fi
+    # /usr/bin/gcc points to an older compiler on both Linux and macOS.
+    - if [ "$CXX" = "g++" ]; then export CXX="g++-9" CC="gcc-9"; fi
+    # /usr/bin/clang points to an older compiler on both Linux and macOS.
+    #
+    # Homebrew's llvm package doesn't ship a versioned clang++ binary, so the values
+    # below don't work on macOS. Fortunately, the path change above makes the
+    # default values (clang and clang++) resolve to the correct compiler on macOS.
+    - if [ "$TRAVIS_OS_NAME" = "linux" ]; then
+        if [ "$CXX" = "clang++" ]; then export CXX="clang++-9" CC="clang-9"; fi;
+      fi
+    - echo ${CC}
+    - echo ${CXX}
+    - ${CXX} --version
+    - cmake --version
+
+
 script:
     # скрипт сборки и тестирования проекта:
     - mkdir build