refs #72, ci tesing for centos

.cirrus.yml

@@ -1,7 +1,6 @@
-freebsd_instance:
-  image_family: freebsd-12-1
-
-task:
+freebsd_task:
+  freebsd_instance:
+    image_family: freebsd-12-1
   install_script: |
     pkg install -y cmake
     pw groupadd testgrp
@@ -11,3 +10,26 @@ task:
     sudo -u testuser .ci/unix-build.sh
   test_script: |
     sudo -u testuser .ci/unix-test.sh
+
+centos7_task:
+  container:
+    image: centos:7
+  install_script: |
+    yum install -y centos-release-scl
+    yum install -y devtoolset-9
+    curl -L https://github.com/Kitware/CMake/releases/download/v3.16.4/cmake-3.16.4-Linux-x86_64.tar.gz | tar xzvf - -C /usr/local --strip-components 1
+  build_script: |
+    source /opt/rh/devtoolset-9/enable && PATH=$PATH:/usr/local/bin .ci/unix-build.sh
+  test_script: |
+    source /opt/rh/devtoolset-9/enable && PATH=$PATH:/usr/local/bin .ci/unix-test.sh
+
+centos8_task:
+  container:
+    image: centos:8
+  install_script: |
+    yum group install -y "Development Tools"
+    curl -L https://github.com/Kitware/CMake/releases/download/v3.16.4/cmake-3.16.4-Linux-x86_64.tar.gz | tar xzvf - -C /usr/local --strip-components 1
+  build_script: |
+    PATH=$PATH:/usr/local/bin .ci/unix-build.sh
+  test_script: |
+    PATH=$PATH:/usr/local/bin .ci/unix-test.sh

test/filesystem_test.cpp

@@ -276,6 +276,11 @@ class TestAllocator
     value_type* allocate(std::size_t n) { return static_cast<value_type*>(::operator new(n * sizeof(value_type))); }
 
     void deallocate(value_type* p, std::size_t) noexcept { ::operator delete(p); }
+
+    template<class U>
+    struct rebind {
+        typedef TestAllocator<U> other;
+    };
 };
 
 template <class T, class U>