+#ifndef MSP_GL_PREDICATE_BACKEND_H_
+#define MSP_GL_PREDICATE_BACKEND_H_
+
+#ifndef MSP_GL_PREDICATE_H_
+#error "predicate_backend.h requires predicate.h"
+#endif
+
+namespace Msp {
+namespace GL {
+
+unsigned get_gl_predicate(Predicate);
+
+} // namespace GL
+} // namespace Msp
+
+#endif