The first step would be to actually define such a subset. And what happens when this subset calls into "full" C++? If you don't want to lose interoperability you have to be pretty conservative with the things you disallow.
In particular since C++ kept the C-style preprocessor "just copy and paste that file in there" includes it would be tricky to handle "sane C++" including "full C++", especially since templated C++ tends to put a massive amount of code in the headers (think boost for instance, which is mostly .hpp "headers"). You'd have to tell the compiler to switch the "sane" flag on and off within the same translation unit depending on the original source of the code. Nothing impossible, but not exactly elegant. Alternatively you could use a new `extern "sane-C++" { ... }`-type block around all your code to tell the compiler what to do.
At any rate you'll have to make sure that your sane subset can always inter-operate with the "wild" C++ without any cross-contamination.
But really I think the main problem is that you'd have trouble getting a consensus on what would be your sane subset. Some devs will tell you to get rid of exceptions altogether, others will tell you that multiple inheritance is the work of the devil. Some will want to ban raw pointers (or at least severely gimp them). And some will want none of that but something else instead.
> But really I think the main problem is that you'd have trouble getting a consensus on what would be your sane subset.
This can probably be solved by adding flexible configuration options (C++ compilers already have plenty). In practice, project leaders would then decide on a set of such options, similar to what happens with code style guidelines.
Perhaps some day a majority of people will agree on a "good" subset of C++ / option set and it will become standardized as a new language or dialect.
In particular since C++ kept the C-style preprocessor "just copy and paste that file in there" includes it would be tricky to handle "sane C++" including "full C++", especially since templated C++ tends to put a massive amount of code in the headers (think boost for instance, which is mostly .hpp "headers"). You'd have to tell the compiler to switch the "sane" flag on and off within the same translation unit depending on the original source of the code. Nothing impossible, but not exactly elegant. Alternatively you could use a new `extern "sane-C++" { ... }`-type block around all your code to tell the compiler what to do.
At any rate you'll have to make sure that your sane subset can always inter-operate with the "wild" C++ without any cross-contamination.
But really I think the main problem is that you'd have trouble getting a consensus on what would be your sane subset. Some devs will tell you to get rid of exceptions altogether, others will tell you that multiple inheritance is the work of the devil. Some will want to ban raw pointers (or at least severely gimp them). And some will want none of that but something else instead.