> EXACTLY. It's f-ing stupid. C's excuse was compilers doing magic on UB or whatever. Java has no such excuse. They just wanted it to behave the same as C/C++ to attract C++ devs.
But... as you yourself are saying, Java's behavior is not "the same as C/C++". Java wraps while in C and C++ signed overflow is undefined. (Interestingly, C++ is now moving away from UB for this, and defining wrapping semantics. While I'm not one for proof by authority, it looks like some very well-informed people disagree with you about the usefulness of this feature.)
Signed integer overflow checking can be almost free. Until it isn't, because it doesn't play nicely with SIMD code. So the code you want to run fastest will pay the biggest price. This article is from 2016 so take it with a grain of salt, but it looks like this can cause 20% to 40% slowdowns: https://blog.regehr.org/archives/1384
I understand that there are performance implications.
But a 20% to 40% slowdown for number crunching in a language that is primarily designed for writing super indirection-heavy, heap-allocation-heavy, application architectures is just nothing.
Having some kind of high performance math section of the standard library would be fine. But the default behavior is, frankly, dangerous. And for a 20% speed up on operations that are probably far less than 1% of the typical Java application?
> a language that is primarily designed for writing super indirection-heavy, heap-allocation-heavy, application architectures
Are there Java design documents that describe the language in these terms, as opposed to something like "a general-purpose object oriented language"?
> But the default behavior is, frankly, dangerous.
You keep saying variations of this, but you haven't really made the case.
True, if you increment a number, you will typically expect the result to be greater. But how many application domains are there where 2^32 - 1 is really the exact upper limit of the range of valid values? I would think that in most cases catching a overflow would come much too late, because the actual error is exceeding some application-specific limit rather than the artificial limit of the range of int. Or put differently, I bet 99.9% of ArrayIndexOutOfBounds errors are because indices leave their legal range without ever overflowing int.
> Are there Java design documents that describe the language in these terms, as opposed to something like "a general-purpose object oriented language"?
I'm sure there aren't. And truthfully, I understand that Java was supposed to be efficient enough to run on small devices and whatnot. But if you look at the evolution of the language as well as where it's mostly used in recent history (no more web browser applets, for example), it seems to me that it has a bit of an identity crisis. Is it the low level implementation language of the JVM platform, or is it a high level app development language?
> True, if you increment a number, you will typically expect the result to be greater.
I'd say this is a pretty big deal for people who are reasoning about code.
> But how many application domains are there where 2^32 - 1 is really the exact upper limit of the range of valid values? I would think that in most cases catching a overflow would come much too late, because the actual error is exceeding some application-specific limit rather than the artificial limit of the range of int.
Agreed. But I've almost never seen code that actually checks value ranges before and after math operations. And Java doesn't make it easy or efficient to do a "newtype" pattern so that the types actually are limited in any meaningful way.
Instead, most enterprisey backend systems I've worked on just accept a JSON request, deserialize some `quantity` fields to an `int`, and go to town with it.
> Or put differently, I bet 99.9% of ArrayIndexOutOfBounds errors are because indices leave their legal range without ever overflowing int.
I'm sure that's true. But indexing a collection is not the issue I was thinking about.
But... as you yourself are saying, Java's behavior is not "the same as C/C++". Java wraps while in C and C++ signed overflow is undefined. (Interestingly, C++ is now moving away from UB for this, and defining wrapping semantics. While I'm not one for proof by authority, it looks like some very well-informed people disagree with you about the usefulness of this feature.)
Signed integer overflow checking can be almost free. Until it isn't, because it doesn't play nicely with SIMD code. So the code you want to run fastest will pay the biggest price. This article is from 2016 so take it with a grain of salt, but it looks like this can cause 20% to 40% slowdowns: https://blog.regehr.org/archives/1384