meson: moving away from meson subprojects in favor of git submodules.

Meson subprojects just have too many problems and limitations and I can foresee
the maintenance headache and the future incoming false-positive bug reports if
we start using meson subprojects.

Comparing to the simplicity of git submodule which also has much better
notifications to help people understand when the submodule is not in sync and
how to remedy to it.

See commit gimp-data@c364adb explaining the main reasons in detail.

.gitlab-ci.yml

@@ -322,6 +322,7 @@ deps-debian-x64:
     - export LD_LIBRARY_PATH="${GIMP_PREFIX}/lib/`gcc -print-multiarch`:$LD_LIBRARY_PATH"
     - export XDG_DATA_DIRS="${GIMP_PREFIX}/share:/usr/local/share:/usr/share"
     - export GI_TYPELIB_PATH="${GIMP_PREFIX}/lib/`gcc -print-multiarch`/girepository-1.0/:${GI_TYPELIB_PATH}"
+    - git submodule update --init
   needs: ["deps-debian-x64"]
 
 gimp-debian-x64:
@@ -542,6 +543,7 @@ gimp-win-x64-cross:
     - apt-cache
   script:
     - export PATH="`pwd`/.local/bin:$PATH"
+    - git submodule update --init
     - crossroad w64 gimp --run="build/windows/gitlab-ci/2_build-gimp-crossroad.sh"
   needs: ["deps-win-x64-cross"]
   artifacts:
@@ -641,6 +643,7 @@ gimp-win-x86-cross:
     - apt-cache
   script:
     - export PATH="`pwd`/.local/bin:$PATH"
+    - git submodule update --init
     - crossroad w32 gimp --run="build/windows/gitlab-ci/2_build-gimp-crossroad.sh"
   needs: ["deps-win-x86-cross", "deps-win-x64-cross"]
   artifacts:
@@ -741,6 +744,7 @@ gimp-win-a64:
     - windows-aarch64
   before_script:
     # C:\msys64\usr\bin\pacman --noconfirm -Syyuu
+    - git submodule update --init
   script:
     - $stuck = Test-Path -Path "C:\msys64\var\lib\pacman\db.lck" -PathType Leaf
     - if ($stuck -eq "True") {
@@ -848,6 +852,7 @@ gimp-win-x64:
     - win32-ps
   before_script:
     - C:\msys64\usr\bin\pacman --noconfirm -Syyuu
+    - git submodule update --init
   script:
     - C:\msys64\usr\bin\bash -lc "bash -x ./build/windows/gitlab-ci/2_build-gimp-msys2.sh"
   artifacts:
@@ -940,6 +945,7 @@ gimp-win-x86:
     - win32-ps
   before_script:
     - C:\msys64\usr\bin\pacman --noconfirm -Syyuu
+    - git submodule update --init
   script:
     - C:\msys64\usr\bin\bash -lc "bash -x ./build/windows/gitlab-ci/2_build-gimp-msys2.sh"
   artifacts:

.gitmodules

@@ -0,0 +1,5 @@
+[submodule "gimp-data"]
+	path = gimp-data
+	url = https://gitlab.gnome.org/GNOME/gimp-data.git
+	shallow = true
+	branch = wip/Jehan/git-submodules

app/gui/icon-themes.c

@@ -255,8 +255,7 @@ icons_apply_theme (Gimp        *gimp,
       gchar *path;
 
       path = g_build_filename (g_getenv ("GIMP_TESTING_ABS_TOP_SRCDIR"),
-                               "subprojects", "gimp-data", "icons",
-                               icon_theme_name, NULL);
+                               "gimp-data", "icons", icon_theme_name, NULL);
       file = g_file_new_for_path (path);
 
       applied = gimp_icons_set_icon_theme (file);

build/windows/gimp.rc.in

@@ -64,6 +64,6 @@ BEGIN
 END
 
 #include "winuser.h"
-1	ICON	QUOTE(TOP_SRCDIR) "/subprojects/gimp-data/images/gimp.ico"
+1	ICON	QUOTE(TOP_SRCDIR) "/gimp-data/images/gimp.ico"
 2	ICON	QUOTE(TOP_SRCDIR) "/build/windows/fileicon.ico"
 CREATEPROCESS_MANIFEST_RESOURCE_ID RT_MANIFEST QUOTE(TOP_SRCDIR) "/build/windows/gimp.manifest"

meson.build

@@ -1827,16 +1827,8 @@ else
   gimp_exe_name=gimpmain_exe_name
 endif
 
-# Loading gimp-data subproject, the versions must be in sync.
-gimp_data = subproject('gimp-data', version: '=' + gimp_version,
-                       default_options: [
-                         'gimp-datadir=' + gimpdatadir,
-                         'gimp-exe='     + gimp_exe_name,
-                       ])
-icons_imgs_sources = gimp_data.get_variable('icons_imgs_sources')
-icons_core_sources = gimp_data.get_variable('icons_core_sources')
-cursors_sources    = gimp_data.get_variable('cursors_sources')
-pickers_sources    = gimp_data.get_variable('pickers_sources')
+# gimp-data submodule
+subdir('gimp-data')
 
 # Libraries (order here is important!)
 subdir('libgimpcolor')

subprojects/gimp-data.wrap

@@ -1,4 +0,0 @@
-[wrap-git]
-url      = https://gitlab.gnome.org/GNOME/gimp-data
-revision = main
-depth    = 1