Merge "build internal API docs with Meson" into main

doc/internal-api/doxygen.cfg.in

@@ -14,6 +14,8 @@ PROJECT_NAME           = "Nix"
 
 PROJECT_NUMBER         = @PACKAGE_VERSION@
 
+OUTPUT_DIRECTORY       = @docdir@
+
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a
 # quick idea about the purpose of the project. Keep the description short.

doc/internal-api/meson.build

@@ -0,0 +1,33 @@
+doxygen_cfg = configure_file(
+  input : 'doxygen.cfg.in',
+  output : 'doxygen.cfg',
+  configuration : {
+    'PACKAGE_VERSION': meson.project_version(),
+    'RAPIDCHECK_HEADERS': rapidcheck_meson.get_variable('includedir'),
+    'docdir' : meson.current_build_dir(),
+  },
+)
+
+internal_api_docs = custom_target(
+  'internal-api-docs',
+  command : [
+    bash,
+    # Meson can you please just give us a `workdir` argument to custom targets...
+    '-c',
+    # We have to prefix the doxygen_cfg path with the project build root
+    # because of the cd in front.
+    'cd @0@ && @1@ @2@/@INPUT0@'.format(
+      meson.project_source_root(),
+      doxygen.full_path(),
+      meson.project_build_root(),
+    ),
+  ],
+  input : [
+    doxygen_cfg,
+  ],
+  output : 'html',
+  install : true,
+  install_dir : datadir / 'doc/nix/internal-api',
+)
+
+alias_target('internal-api-html', internal_api_docs)