Although it doesn't have the same level of compile-time guarantees, there are ru...

bmacho · on Oct 2, 2024

> Although it doesn't have the same level of compile-time guarantees, there are runtime checks to ensure memory safety if you use Debug or ReleaseSafe.

it is not very good, as

    const std = @import("std");
    const print = std.debug.print;

    fn foo() fn() *u32 {
        
        const T = struct {

            fn bar() *u32 {
                var x: u32 = 123;
                return &x;
            }

        };
        
        return T.bar;
    }

    pub fn main() void {

        print("Resultt: {}", .{foo()().*});

    }

outputs 123 in debug[0] and 0 in ReleaseSafe[1] instead of giving a Runtime Error.

[0] https://zig.godbolt.org/z/ezTr3zP6a

[1] https://zig.godbolt.org/z/3ExeveT69

DanielHB · on Oct 2, 2024

Just wondering, if you don't care about that much about the performance for your application, is it okay to use the runtime checks compilation in production?

Like say I have a really weird issue I can't seem to find locally, can I switch my production server to this different compilation mode temporarily to get better logs? Can I run my development environment with it on all the time?

laserbeam · on Oct 2, 2024

Certain classes of programs should be built as ReleaseSafe rather than ReleaseFast to keep many of the runtime checks. It's perfectly reasonable to write a database and build as ReleaseSafe, but also make a game and build it as ReleaseFast.

sciolistse · on Oct 2, 2024

You can definitely use ReleaseSafe, you can also switch modes during compilation. so you can call '@setRuntimeSafety(false)' at the start of a scope to disable runtime safety for performance critical sections.

DanielHB · on Oct 2, 2024

this is an amazing feature

jonathrg · on Oct 2, 2024

Sure, an application built in Debug mode with a compiled language is going to be much faster than if you implemented it in an interpreted language. Given how much of the world runs on Python, PHP and Javascript, your zig application in debug mode is probably going to run just fine.