You raise a good point about newer compilers doing much deeper analysis of the code than older compilers. I have experienced the horror of compiling an old, nominally clean C++11 code base with the latest version of clang++ and seeing a small avalanche of errors and warnings that weren't picked up by the compiler when that code was written.

It creates a lot of work, and frequently the nature of the bugs are not material (i.e. in context they may not produce a runtime fault), but I do find it to be good hygiene. I used to do builds with two different compilers for the same purpose, though that found compiler bugs as often as it found issues in the code.