WIP: build internal API docs with Meson

Change-Id: I98f0017891c25b06866c15f7652fe74f706ec8e1

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 +1,28 @@
+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(
+  # FIXME(Qyriad): alias to internal-api-html
+  'internal-api-docs',
+  command : [
+    bash,
+    '-c',
+    'cd @0@ && @INPUT0@ @1@/@INPUT1@'.format(
+      meson.project_source_root(), meson.project_build_root()
+    ),
+  ],
+  input : [
+    doxygen.full_path(),
+    doxygen_cfg,
+  ],
+  output : 'html',
+  install : true,
+  install_dir : datadir / 'doc/nix',
+)

meson.build

@@ -278,6 +278,10 @@ lsof = find_program('lsof')
 bison = find_program('bison')
 flex = find_program('flex')
 
+if enable_docs # FIXME: internal-api-docs
+  doxygen = find_program('doxygen')
+endif
+
 # This is how Nix does generated headers...
 # other instances of header generation use a very similar command.
 # FIXME(Qyriad): do we really need to use the shell for this?
@@ -396,6 +400,7 @@ subdir('misc')
 
 if enable_docs
   subdir('doc/manual')
+  subdir('doc/internal-api')
 endif
 
 if enable_tests