Index: libcfa/prelude/builtins.c
===================================================================
--- libcfa/prelude/builtins.c	(revision 8477fc4bdb376b6d926b081d9cd0932f9df33a7c)
+++ libcfa/prelude/builtins.c	(revision d83b266a3965d96a2cd3cfe94b833e4d20ca1cab)
@@ -10,6 +10,6 @@
 // Created On       : Fri Jul 21 16:21:03 2017
 // Last Modified By : Peter A. Buhr
-// Last Modified On : Tue Jul 20 17:31:40 2021
-// Update Count     : 128
+// Last Modified On : Wed Jul 21 13:31:34 2021
+// Update Count     : 129
 //
 
@@ -77,4 +77,6 @@
 // implicit increment, decrement if += defined, and implicit not if != defined
 
+// C11 reference manual Section 6.5.16 (page101): "An assignment expression has the value of the left operand after the
+// assignment, but is not an lvalue." Hence, return a value not a reference.
 static inline {
 	forall( T | { T ?+=?( T &, one_t ); } )