We already have that: `gcc -Wall -Wextra`, and a few more flags for specific things that some projects find too restrictive.

Assuming "that" means "very detailed control over language features" I would say no, these flags don't provide that.

Only very few flags warn or disable the use of entire language features. Most are warnings against dangerous ways of using some of the features.

I believe gp meant Javascript's "use strict" equivalent in C++, which I would say is comparable to the compiler flags.

"use strict" isn't comparable to warning flags at all, because it changes the behavior of code. I only brought it up because it can be applied selectively within function scope, not specifically for what it does.

I think what we need is a way to selectively disable language features. Changing the behavior of existing features is a much more questionable thing to do in my view.

The big question is if it's possible to disable some features without affecting how other features must work. It failed miserably for exceptions, but exceptions are a cross cutting sort of concern.