Are you seriously suggesting that the vast majority of C code causes signed int overflows or dereferences invalid pointers?
Not sure about the C code bases you've been spending time in, but in the ones I've looked at, the overwhelming majority of the code has been well-defined by either the C standard or the implementation. In the cases where it hasn't, the vast majority of those cases were genuine bugs that needed fixing, and the fix made the code well-defined.
The number of codebases I've seen that actually relied on unspecified behaviour, or on whatever the current compiler/OS/CPU happened to do with undefined behaviour, is miniscule. (Or an entry in an obfuscated/underhanded coding contest.)
Not sure about the C code bases you've been spending time in, but in the ones I've looked at, the overwhelming majority of the code has been well-defined by either the C standard or the implementation. In the cases where it hasn't, the vast majority of those cases were genuine bugs that needed fixing, and the fix made the code well-defined.
The number of codebases I've seen that actually relied on unspecified behaviour, or on whatever the current compiler/OS/CPU happened to do with undefined behaviour, is miniscule. (Or an entry in an obfuscated/underhanded coding contest.)