for g++-11

GNUmakefile.in

@@ -160,7 +160,7 @@ else
 src/revision.hpp:
 	@ echo 'const char kRevision[] = R"(' > $@
 	@ echo libcifpp-version: $(VERSION) >> $@
-	@ echo Date:   $$(date --iso-8601) >> $@
+	@ echo Date:   $$(TZ=GMT date +"%Y-%m-%d") >> $@
 	@ echo ')";' >> $@
 
 endif

include/cif++/Cif++.hpp

@@ -34,6 +34,7 @@
 #include <set>
 #include <list>
 #include <array>
+#include <optional>
 
 #include "cif++/CifUtils.hpp"
 

src/Compound.cpp

@@ -28,6 +28,7 @@
 
 #include <map>
 #include <numeric>
+#include <mutex>
 #include <shared_mutex>
 
 #include <boost/algorithm/string.hpp>

src/PDB2Cif.cpp

@@ -1008,7 +1008,7 @@ class PDBFileParser
 		if (i != mLinks.end())
 			return { i->a == atom ? i->b : i->a, true };
 
-		return {{}, false};
+		return {};
 	}
 
 	// ----------------------------------------------------------------