The Clang Static Analyzer uses immutable data structures. Here, for instance, is its immutable list implementation: https://github.com/llvm/llvm-project/blob/ma

The Clang Static Analyzer uses immutable data structures. Here, for instance, is its immutable list implementation: https://github.com/llvm/llvm-project/blob/master/llvm/include/llvm/ADT/ImmutableList.h https://github.com/llvm/llvm-project/blob/master/llvm/includ... The data structures are used during program state exploration because they are more memory efficient than storing many copies of the program state with small mutations.