I haven't read the book. What's the gist of the recommendations for addressing those issues? SaferCPlusPlus addresses the signed/unsigned issue by providing compatible substitutes[1] for "int" and "size_t" that automatically handle it. And it addresses the integer underflow/overflow issue by recommending another compatible "int" substitute[2] and introducing the concept (but not yet the implementation) of "quarantined" types for untrusted input values.

[1] https://github.com/duneroadrunner/SaferCPlusPlus#cint-csize_...

[2] https://github.com/robertramey/safe_numerics