I didn't say nothing would work. I said it'd be known as the one where nothing works. Think: IE6. It implemented like 95% of all web standards as of 2006. But this missing 5% was the difference between being at the forefront of progress and holding back the entire industry.
Today, IE6's 95% would be less than 10%. So you'd need to implement several times more features than IE6 had to be even remotely close to the status of unworkable mess that webdevs are better off not supporting.
Low-level exploits like heartbleed are quite rare actually. The vast majority of security bugs in Chrome and Firefox are in unsafely handling edge cases in parsing HTML and other media types, not isolating script execution enough, and bugs in runtime interfaces (cookies, local storage, mic&cam APIs, location APIs, etc.) Realistically, there's no way to avoid these bugs - browser engine has too much inherent complexity, statistically you're bound to mke amistake every so often. Moreover, IIRC about half of those bugs are caused by buffer overflows and similar memory bugs. So by using Rust, you can expect to have half as many security holes than you'd have otherwise. The number is still in the thousands either way.
FWIW C++ can do bound checks aka hardened STL. On the other hand google did riir some of their programs and removed bound checks there for speed, welcome to real world, so absence of bound checks is not a mistake, but an intended performance goal.
Google is consciously making Chrome less secure because otherwise the performance is unacceptable. The end result is about 300 CVEs every year for the last 10 years. That's for an almost 20 year old project that had most of its security issues resolved very early on.
And you're saying somebody who is not Google can make a brand new browser engine from scratch in 2026, have it perform good enough to be actually usable in practice, and not be an absolute security nightmare?
Today, IE6's 95% would be less than 10%. So you'd need to implement several times more features than IE6 had to be even remotely close to the status of unworkable mess that webdevs are better off not supporting.
Low-level exploits like heartbleed are quite rare actually. The vast majority of security bugs in Chrome and Firefox are in unsafely handling edge cases in parsing HTML and other media types, not isolating script execution enough, and bugs in runtime interfaces (cookies, local storage, mic&cam APIs, location APIs, etc.) Realistically, there's no way to avoid these bugs - browser engine has too much inherent complexity, statistically you're bound to mke amistake every so often. Moreover, IIRC about half of those bugs are caused by buffer overflows and similar memory bugs. So by using Rust, you can expect to have half as many security holes than you'd have otherwise. The number is still in the thousands either way.