[tepl] io-error-info-bars: #error in case the header is #included directly

[Sébastien Wilmet <swilmet src gnome org>]

commit 9885194bd5e9f900bdf70677cf441fa245b226fb
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Wed Nov 11 15:09:52 2020 +0100

    io-error-info-bars: #error in case the header is #included directly

 tepl/tepl-io-error-info-bars.h | 4 ++++
 1 file changed, 4 insertions(+)
---
diff --git a/tepl/tepl-io-error-info-bars.h b/tepl/tepl-io-error-info-bars.h
index 978faa0..a0bbe8e 100644
--- a/tepl/tepl-io-error-info-bars.h
+++ b/tepl/tepl-io-error-info-bars.h
@@ -5,6 +5,10 @@
 #ifndef TEPL_IO_ERROR_INFO_BARS_H
 #define TEPL_IO_ERROR_INFO_BARS_H
 
+#if !defined (TEPL_H_INSIDE) && !defined (TEPL_COMPILATION)
+#error "Only <tepl/tepl.h> can be included directly."
+#endif
+
 #include <gio/gio.h>
 #include <tepl/tepl-info-bar.h>