gst_all_1.gstreamer: disable introspection if unavailable

pkgs/development/libraries/gstreamer/core/default.nix

@@ -15,9 +15,11 @@
 , lib
 , Cocoa
 , CoreServices
-, gobject-introspection
 , rustc
 , testers
+, gobject-introspection
+, buildPackages
+, withIntrospection ? lib.meta.availableOn stdenv.hostPlatform gobject-introspection && stdenv.hostPlatform.emulatorAvailable buildPackages
 , libunwind
 # darwin.libunwind doesn't have pkg-config definitions so meson doesn't detect it.
 , withLibunwind ? !stdenv.isDarwin && lib.meta.availableOn stdenv.hostPlatform libunwind
@@ -60,10 +62,11 @@ stdenv.mkDerivation (finalAttrs: {
  makeWrapper
  glib
  bash-completion
- gobject-introspection
  rustc
  ] ++ lib.optionals stdenv.isLinux [
  libcap # for setcap binary
+ ] ++ lib.optionals withIntrospection [
+ gobject-introspection
  ] ++ lib.optionals enableDocumentation [
  hotdoc
  ];
@@ -88,6 +91,7 @@ stdenv.mkDerivation (finalAttrs: {
  mesonFlags = [
  "-Ddbghelp=disabled" # not needed as we already provide libunwind and libdw, and dbghelp is a fallback to those
  "-Dexamples=disabled" # requires many dependencies and probably not useful for our users
+ (lib.mesonEnable "introspection" withIntrospection)
  (lib.mesonEnable "doc" enableDocumentation)
  (lib.mesonEnable "libunwind" withLibunwind)
  (lib.mesonEnable "libdw" withLibunwind)