+@subsubsection contributing_todo_mc_state_compare Overhaul the state comparison code
+
+The state comparison code is quite complicated. It has very long functions and
+is programmed mostly using C idioms and is difficult to understanda and debug.
+It is in need or an overhaul:
+
+ - cleanup, refactorisation, usage of C++ features.
+
+ - The state comparison code works by infering types of blocks allocated on the
+ heap by following pointers from known roots (global variables, local
+ variables). Usually the first type found for a given block is used even if
+ a better one could be found later. By using a first pass of type inference,
+ on each snapshot before comparing the states, we might use a better type
+ information on the different blocks.
+
+ - We might benefit from adding logic for handling some known types. For
+ example, both `std::string` and `std::vector` have a capacity which might
+ be larger than the current size of the container. We should might ignore
+ the corresponding elements when comparing the states and infering the types.
+
+ - Another difficulty in the state comparison code is the detection of
+ dangling pointers. We cannot easily know if a pointer is dangling and
+ dangling pointers might lead us to choose the wrong type when infering
+ heap blocks. We might mitigate this problem by delaying the reallocation of
+ a freed block until there is no blocks pointing to it anymore using some
+ sort of basic garbage-collector.
+
+@subsubsection contributing_todo_state_hashing Hashing the states
+
+In order to speed up the state comparison an idea was to create a hash of the
+state. Only states with the same hash would need to be compared using the
+state comparison algorithm. Some information should not be inclueded in the
+hash in order to avoid considering different states which would otherwise
+would have been considered equal.
+
+The stated could be indexed by their hash. Currently they are indexed
+by the number of processes and the amount of heap currently allocated
+(see `DerefAndCompareByNbProcessesAndUsedHeap`).
+
+Good candidate informations for the state hashing:
+
+ - number of processes;
+
+ - their backtraces (instruction addresses);
+
+ - their current simcall numbers;
+
+ - some simcall arguments (eg. number of elements in a waitany);
+
+ - number of pending communications;
+
+ - etc.
+
+Some basic infrastructure for this is already in the code (see `mc_hash.cpp`)
+but it is currently disabled.
+
+@subsubsection contributing_todo_mc_separation Separate the model-checker code from libsimgrid
+
