[glib: 1/2] Meson: Override every dependency glib provides

[Philip Withnall <pwithnall src gnome org>]

commit 10280deebdb6bfa96e24325548c15a6085d6bdf2
Author: Xavier Claessens <xavier claessens collabora com>
Date:   Sun Apr 5 00:34:04 2020 -0400

    Meson: Override every dependency glib provides
    
    Meson 0.54.0 added a new method meson.override_dependency() that must be
    used to ensure dependency consistency. This patch ensures a project that
    depends on glib will never link to a mix of system and subproject
    libraries. It would happen in such cases:
    
    The system has glib 2.40 installed, and a project does:
    dependency('glib-2.0', version: '>=2.60',
      fallback: ['glib', 'glib_dep'])
    dependency('gobject-2.0')
    
    The first call will configure glib subproject because the system libglib
    is too old, but the 2nd call will return system libgobject.
    
    By overriding 'gobject-2.0' dependency while configuring glib subproject
    during the first call, meson knows that on the 2nd call it must return
    the subproject dependency instead of system dependency.
    
    This also has the nice side effect that with Meson >0.54.0 an
    application depending on glib can declare the fallback without knowing
    the dependency variable name: dependency('glib-2.0', fallback: 'glib').

 gio/meson.build     | 19 +++++++++++++++----
 glib/meson.build    |  4 ++++
 gmodule/meson.build |  6 ++++++
 gobject/meson.build |  4 ++++
 gthread/meson.build |  4 ++++
 5 files changed, 33 insertions(+), 4 deletions(-)
---
diff --git a/gio/meson.build b/gio/meson.build
index 2ef60eda9..39e246b9b 100644
--- a/gio/meson.build
+++ b/gio/meson.build
@@ -813,6 +813,10 @@ endif
 
 schemas_subdir = join_paths('glib-2.0', 'schemas')
 
+libgio_dep = declare_dependency(link_with : libgio,
+  dependencies : [libgmodule_dep, libgobject_dep, gioenumtypes_dep],
+  include_directories : [gioinc])
+
 pkg.generate(libgio,
   libraries_private : [osx_ldflags],
   requires : ['glib-2.0', 'gobject-2.0'],
@@ -835,6 +839,11 @@ pkg.generate(libgio,
   description : 'glib I/O library',
 )
 
+if meson.version().version_compare('>=0.54.0')
+  meson.override_dependency('gio-2.0', libgio_dep)
+endif
+
+
 if host_system == 'windows'
   pkg.generate(requires : ['gobject-2.0', 'gmodule-no-export-2.0', 'gio-2.0'],
     subdirs : ['gio-win32-2.0'],
@@ -844,6 +853,9 @@ if host_system == 'windows'
     name : 'GIO Windows specific APIs',
     description : 'Windows specific headers for glib I/O library',
   )
+  if meson.version().version_compare('>=0.54.0')
+    meson.override_dependency('gio-win32-2.0', libgio_dep)
+  endif
 else
   pkg.generate(requires : ['gobject-2.0', 'gio-2.0'],
     subdirs : ['gio-unix-2.0'],
@@ -853,12 +865,11 @@ else
     name : 'GIO unix specific APIs',
     description : 'unix specific headers for glib I/O library',
   )
+  if meson.version().version_compare('>=0.54.0')
+    meson.override_dependency('gio-unix-2.0', libgio_dep)
+  endif
 endif
 
-libgio_dep = declare_dependency(link_with : libgio,
-  dependencies : [libgmodule_dep, libgobject_dep, gioenumtypes_dep],
-  include_directories : [gioinc])
-
 if host_system == 'windows'
   # Hack till https://github.com/mesonbuild/meson/issues/2324 is fixed
   libgiounix_dep = dependency('', required : false)
diff --git a/glib/meson.build b/glib/meson.build
index aaf5f00f5..3869f7a9d 100644
--- a/glib/meson.build
+++ b/glib/meson.build
@@ -385,6 +385,10 @@ pkg.generate(libglib,
   description : 'C Utility Library',
 )
 
+if meson.version().version_compare('>=0.54.0')
+  meson.override_dependency('glib-2.0', libglib_dep)
+endif
+
 # On Windows, glib needs a spawn helper for g_spawn* API
 if host_system == 'windows'
   if host_machine.cpu_family() == 'x86'
diff --git a/gmodule/meson.build b/gmodule/meson.build
index 9801c9476..b1a5a11a9 100644
--- a/gmodule/meson.build
+++ b/gmodule/meson.build
@@ -120,3 +120,9 @@ pkg.generate(libraries : [libgmodule, export_dynamic_ldflags],
 libgmodule_dep = declare_dependency(link_with : libgmodule,
   include_directories : [gmoduleinc],
   dependencies : [libglib_dep])
+
+if meson.version().version_compare('>=0.54.0')
+  meson.override_dependency('gmodule-no-export-2.0', libgmodule_dep)
+  meson.override_dependency('gmodule-export-2.0', libgmodule_dep)
+  meson.override_dependency('gmodule-2.0', libgmodule_dep)
+endif
diff --git a/gobject/meson.build b/gobject/meson.build
index 85e283bab..536f15393 100644
--- a/gobject/meson.build
+++ b/gobject/meson.build
@@ -143,6 +143,10 @@ libgobject_dep = declare_dependency(link_with : libgobject,
   include_directories : [gobjectinc],
   dependencies : [libglib_dep, glib_enumtypes_dep])
 
+if meson.version().version_compare('>=0.54.0')
+  meson.override_dependency('gobject-2.0', libgobject_dep)
+endif
+
 executable('gobject-query', 'gobject-query.c',
   install : true,
   dependencies : [libglib_dep, libgobject_dep])
diff --git a/gthread/meson.build b/gthread/meson.build
index d4fca40b8..808e889cc 100644
--- a/gthread/meson.build
+++ b/gthread/meson.build
@@ -34,3 +34,7 @@ pkg.generate(libgthread,
 )
 
 libgthread_dep = declare_dependency(link_with : libgthread)
+
+if meson.version().version_compare('>=0.54.0')
+  meson.override_dependency('gthread-2.0', libgthread_dep)
+endif