try better meson_config.rs handling

.gitignore

@@ -1,2 +1 @@
 target/
-src/meson_config.rs

meson.build

@@ -65,6 +65,7 @@ custom_target(
   build_by_default: true,
   build_always_stale: true,
   depends: [audrey_c, blueprints],
+  input: config_rs,
   console: true,
   # means nothing (always stale and uncopied), we can't cp since env: drops the /bin/sh wrapper
   output: meson.project_name(),

src/meson.build

@@ -22,18 +22,11 @@ audrey_deps = [
 
 audrey_sources += removeme
 
-configure_file(
+config_rs = configure_file(
   output: 'meson_config.rs',
   input: 'meson_config.rs.in',
   configuration: config_h,
 )
-# awful hack to put the configured file back in source
-run_command(
-  'cp',
-  meson.project_build_root() / 'src' / 'meson_config.rs',
-  meson.project_source_root() / 'src' / 'meson_config.rs',
-  check: true,
-)
 
 audrey_c = static_library(
   'audrey',

src/meson_config.rs

@@ -0,0 +1 @@
+include!(concat!(env!("MESON_BUILD_ROOT"), "/src/meson_config.rs"));