headers: check that _GL_INLINE_HEADER_BEGIN is defined

[gnulib.git] / lib / gl_oset.h

diff --git a/lib/gl_oset.h b/lib/gl_oset.h
index 575ffd3..5134065 100644 (file)
--- a/lib/gl_oset.h
+++ b/lib/gl_oset.h
@@ -21,6 +21,9 @@
 #include <stdbool.h>
 #include <stddef.h>
 
+#ifndef _GL_INLINE_HEADER_BEGIN
+ #error "Please include config.h first."
+#endif
 _GL_INLINE_HEADER_BEGIN
 #ifndef GL_OSET_INLINE
 # define GL_OSET_INLINE _GL_INLINE