[dconf: 4/6] build: Remove libdconf-common-hidden

[Daniel Playfair Cal <danielplayfaircal src gnome org>]

commit 7526617ab25d314f646c5ae874197b8846de2a64
Author: Iñigo Martínez <inigomartinez gmail com>
Date:   Mon Aug 13 23:52:05 2018 +0200

    build: Remove libdconf-common-hidden
    
    `libdconf-common-hidden` is built to hide symbols not necessary
    in the `gsettings` gio module that only needs to expose
    `g_io_module_[load|query|unload]` symbols.
    
    To achieve this a symbol map along with `version-script` linker flag
    is used. Thanks to this only the necessary symbols are exposed,
    building `libdconf-common-hidden` static library is not necessary
    anymore and the existing dependencies can be used.

 common/meson.build    | 14 --------------
 gsettings/meson.build | 15 ++++++++-------
 gsettings/symbol.map  |  8 ++++++++
 3 files changed, 16 insertions(+), 21 deletions(-)
---
diff --git a/common/meson.build b/common/meson.build
index 61af2f9a..befa9bcc 100644
--- a/common/meson.build
+++ b/common/meson.build
@@ -30,17 +30,3 @@ libdconf_common_dep = declare_dependency(
   dependencies: glib_dep,
   link_with: libdconf_common,
 )
-
-libdconf_common_hidden = static_library(
-  'dconf-common-hidden',
-  sources: sources,
-  include_directories: top_inc,
-  dependencies: glib_dep,
-  c_args: dconf_c_args + cc.get_supported_arguments('-fvisibility=hidden'),
-  pic: true,
-)
-
-libdconf_common_hidden_dep = declare_dependency(
-  dependencies: glib_dep,
-  link_with: libdconf_common_hidden,
-)
diff --git a/gsettings/meson.build b/gsettings/meson.build
index ee0f723c..94634530 100644
--- a/gsettings/meson.build
+++ b/gsettings/meson.build
@@ -1,18 +1,19 @@
-# We use the libraries directly, as the dependency objects use
-# link_whole; this avoids the gsettings backend module exposing
-# symbols other than g_io_module_*
 backend_deps = [
-  libdconf_common_hidden,
-  libdconf_gdbus_thread,
+  libdconf_common_dep,
+  libdconf_gdbus_thread_dep,
 ]
 
+symbol_map = join_paths(meson.current_source_dir(), 'symbol.map')
+ldflags = cc.get_supported_link_arguments('-Wl,--version-script,@0@'.format(symbol_map))
+
 libdconf_settings = shared_library(
   'dconfsettings',
   sources: 'dconfsettingsbackend.c',
   include_directories: top_inc,
-  link_with: backend_deps,
-  dependencies: gio_dep,
+  dependencies: backend_deps,
   c_args: dconf_c_args,
+  link_args: ldflags,
+  link_depends: symbol_map,
   install: true,
   install_dir: gio_module_dir,
 )
diff --git a/gsettings/symbol.map b/gsettings/symbol.map
new file mode 100644
index 00000000..43ed5a77
--- /dev/null
+++ b/gsettings/symbol.map
@@ -0,0 +1,8 @@
+{
+global:
+  g_io_module_load;
+  g_io_module_unload;
+  g_io_module_query;
+local:
+  *;
+};