boost

appveyor.yml

@@ -9,6 +9,7 @@ install:
   - cmd: pip install ninja meson
   # Set up the build environment
   - cmd: '"C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvarsall.bat" x86_amd64'
+  - cmd: set BOOST_ROOT=C:\Libraries\boost_1_71_0
 
 build_script:
   - cmd: meson --backend=ninja builddir