gl/build: build with implicit_include_directories : false

Fixes case-insensitive file systems confusing gst-libs/gst/gl/egl/egl.h
with EGL/egl.h when the source directory gst-libs/gst/gl is automatically
added to the compiler's search path.

Due to mesonbuild/meson#7582 we also need to
perform manual enumtype generation.

Fixes https://gitlab.freedesktop.org/gstreamer/gst-plugins-base/-/issues/814

gst-libs/gst/gl/gl_mkenum.py

@@ -0,0 +1,55 @@
+#!/usr/bin/env python3
+
+# This is in its own file rather than inside meson.build
+# because a) mixing the two is ugly and b) trying to
+# make special characters such as \n go through all
+# backends is a fool's errand.
+
+import sys, subprocess
+
+h_array = ['--fhead',
+           "#pragma once\n\n#include <gst/gst.h>\n#include <gst/gl/gstgl_fwd.h>\nG_BEGIN_DECLS\n",
+           '--fprod',
+           "\n/* enumerations from \"@basename@\" */\n",
+           '--vhead',
+           "GST_GL_API\nGType @enum_name@_get_type (void);\n#define GST_TYPE_@ENUMSHORT@ (@enum_name@_get_type())\n",
+           '--ftail',
+           "G_END_DECLS"
+]
+
+c_array = ['--fhead',
+           "#ifdef HAVE_CONFIG_H\n#include \"config.h\"\n#endif\n#include \"gl-enumtypes.h\"\n\n#include <gst/gl/gl.h>\n\n#define C_ENUM(v) ((gint) v)\n#define C_FLAGS(v) ((guint) v)",
+           '--fprod',
+           "\n/* enumerations from \"@basename@\" */",
+           '--vhead',
+           "GType\n@enum_name@_get_type (void)\n{\n  static volatile gsize g_define_type_id__volatile = 0;\n  if (g_once_init_enter (&g_define_type_id__volatile)) {\n    static const G@Type@Value values[] = {",
+           '--vprod',
+           "      { C_@TYPE@ (@VALUENAME@), \"@VALUENAME@\", \"@valuenick@\" },",
+           '--vtail',
+           "      { 0, NULL, NULL }\n    };\n    GType g_define_type_id = g_@type@_register_static (\"@EnumName@\", values);\n    g_once_init_leave (&g_define_type_id__volatile, g_define_type_id);\n  }\n  return g_define_type_id__volatile;\n}\n"
+]
+
+cmd = []
+argn = 1
+# Find the full command needed to run glib-mkenums
+# On UNIX-like, this is just the full path to glib-mkenums
+# On Windows, this is the full path to interpreter + full path to glib-mkenums
+for arg in sys.argv[1:]:
+    cmd.append(arg)
+    argn += 1
+    if arg.endswith('glib-mkenums'):
+        break
+ofilename = sys.argv[argn]
+headers = sys.argv[argn + 1:]
+
+if ofilename.endswith('.h'):
+    arg_array = h_array
+else:
+    arg_array = c_array
+
+cmd_array = cmd + arg_array + headers
+pc = subprocess.Popen(cmd_array, stdout=subprocess.PIPE)
+(stdo, _) = pc.communicate()
+if pc.returncode != 0:
+    sys.exit(pc.returncode)
+open(ofilename, 'wb').write(stdo)

gst-libs/gst/gl/meson.build

@@ -973,15 +973,20 @@ if build_gstgl
     install_dir : get_option('libdir') + '/gstreamer-1.0/include/gst/gl',
     configuration : glconf)
 
-  gl_enums = gnome.mkenums_simple('gl-enumtypes',
-    sources : gir_gl_headers,
-    body_prefix : '#ifdef HAVE_CONFIG_H\n#include "config.h"\n#endif',
-    header_prefix : '#include <gst/gl/gl-prelude.h>',
-    decorator : 'GST_GL_API',
-    install_header: true,
-    install_dir : join_paths(get_option('includedir'), 'gstreamer-1.0/gst/gl'))
-  gl_enumtypes_c = gl_enums[0]
-  gl_enumtypes_h = gl_enums[1]
+  glib_mkenums = find_program('glib-mkenums')
+  mkenums = find_program('gl_mkenum.py')
+  gl_enumtypes_h = custom_target('gstglenumtypes_h',
+    output : 'gl-enumtypes.h',
+    input : gir_gl_headers,
+    install : true,
+    install_dir : join_paths(get_option('includedir'), 'gstreamer-1.0/gst/gl/'),
+    command : [mkenums, glib_mkenums, '@OUTPUT@', '@INPUT@'])
+
+  gl_enumtypes_c = custom_target('gstglenumtypes_c',
+    output : 'gl-enumtypes.c',
+    input : gir_gl_headers,
+    depends : [gl_enumtypes_h],
+    command : [mkenums, glib_mkenums, '@OUTPUT@', '@INPUT@'])
   gen_sources = [gl_enumtypes_h]
 
   gstgl = library('gstgl-' + api_version,
@@ -995,7 +1000,9 @@ if build_gstgl
     darwin_versions : osxversion,
     install : true,
     dependencies : [gst_base_dep, video_dep, allocators_dep, gmodule_dep,
-                    gl_lib_deps, gl_platform_deps, gl_winsys_deps, gl_misc_deps])
+                    gl_lib_deps, gl_platform_deps, gl_winsys_deps, gl_misc_deps],
+    # don't confuse EGL/egl.h with gst-libs/gl/egl/egl.h on case-insensitive file systems
+    implicit_include_directories : true)
 
   if build_gir
     gl_gir = gnome.generate_gir(gstgl,