meson: Fix valadoc documentation generation

autotools is able to generate documentation by using the `valadoc`
program. However, meson is not able to generate this documentation.

meson build files has been fixed to be able to generate `valadoc`
documentation.

libgitg-ext/meson.build

@@ -84,7 +84,7 @@ pkg.generate(
 )
 
 # FIXME: does not work due to missing proper valadoc support
-if enable_docs
+if get_option('docs')
   vala_pkgs = [
     '--pkg', 'ggit-1.0',
     '--pkg', 'gio-2.0',
@@ -94,18 +94,20 @@ if enable_docs
   ]
 
   valaproc_cmd = [
-    valadoc,
+    find_program('valadoc'),
     '--directory', join_paths(source_root, 'docs'),
     '--package-name', 'gitgext',
     vala_pkgs,
     '--basedir', source_root,
-    '--vapidir', join_paths(build_root, 'gitg'),
-    sources,
+    '--vapidir', vapi_dir,
+    '--vapidir', libgitg_dir,
+    sources + [join_paths(libgitg_build_dir, libgitg_vapi_name)],
   ]
 
   run_target(
     'libgitg-ext-docs',
     command: valaproc_cmd,
+    depends: libgitg,
   )
 endif
 

meson.build

@@ -47,6 +47,7 @@ pkg = import('pkgconfig')
 source_root = meson.current_source_dir()
 build_root = meson.current_build_dir()
 
+libgitg_dir = join_paths(source_root, 'libgitg')
 po_dir = join_paths(source_root, 'po')
 vapi_dir = join_paths(source_root, 'vapi')
 
@@ -173,12 +174,6 @@ config_h.set_quoted('PLATFORM_NAME', platform_name)
 
 g_ir_compiler = find_program('g-ir-compiler')
 
-enable_docs = get_option('docs')
-if enable_docs
-  docs_dir = join_paths(source_root, 'docs')
-  valadoc = find_program('valadoc')
-endif
-
 subdir('po')
 subdir('contrib/xml')
 subdir('contrib/ide')