[gtk/backports-for-4-4: 9/19] build: Check that introspection is enabled for docs build

[Matthias Clasen <matthiasc src gnome org>]

commit f80170029d09deb69422b314fee4a6f83e77623c
Author: Benjamin Otte <otte redhat com>
Date:   Sun Aug 29 02:47:34 2021 +0200

    build: Check that introspection is enabled for docs build

 docs/reference/meson.build | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/docs/reference/meson.build b/docs/reference/meson.build
index f69f568f2e..4ca44b67e8 100644
--- a/docs/reference/meson.build
+++ b/docs/reference/meson.build
@@ -5,6 +5,10 @@ gidocgen = find_program('gi-docgen', required: get_option('gtk_doc'))
 
 docs_dir = gtk_datadir / 'doc'
 
+if get_option('gtk_doc') and not build_gir
+  error('API reference requires introspection.')
+endif
+
 subdir('gdk')
 subdir('gsk')
 subdir('gtk')