Nothing actually works as advertised in Meson.

sfmldemo/meson.build

@@ -1,11 +1,8 @@
 project('sfmldemo', 'cpp',
-  default_options: ['cpp_std=c++17'])
-
-if host_machine.system() == 'windows'
-  defaults = ['library_default=static']
-else
-  defaults = []
-endif
+  default_options: [
+    'cpp_std=c++17',
+    'default_library=static'
+    ])
 
 dependencies = [
   dependency('sfml'),
@@ -16,5 +13,4 @@ dependencies = [
 executable('sfmldemo', 'main.cpp',
   win_subsystem: 'windows',
   cpp_args: '-DFMT_HEADER_ONLY',
-  override_options: defaults,
   dependencies: dependencies)