integer overflow with new for loop

[IntegratedQuantum]

Zig Version

0.11.0-dev.1711+dc1f50e50

Steps to Reproduce and Observed Behavior

const std = @import("std");

pub fn main() void {
	var start: u32 = 1;
	var end: u32 = 0;
	for(start..end) |x| {
		std.log.info("{}", .{x});
	}
}

output:

$ zig run test.zig
thread 28234 panic: integer overflow
/home/mint/Desktop/test.zig:6:6: 0x20b56c in main (test)
 for(start..end) |x| {
     ^
/home/mint/Downloads/zig/lib/std/start.zig:607:22: 0x20aa25 in posixCallMainAndExit (test)
            root.main();
                     ^
/home/mint/Downloads/zig/lib/std/start.zig:376:5: 0x20a4d1 in _start (test)
    @call(.never_inline, posixCallMainAndExit, .{});
    ^
Aborted (core dumped)

Expected Behavior

I would expect these two loops to behave equivalent:

for(start..end) |x| {
	...
}
// should behave like
var x: usize = start
while(x < end) : (x += 1) {
	...
}

And therefor no integer overflow should happen.

workaround for anyone else who stumbles over this

for(start..@max(start, end)) |x| {
	...
}

[wooster0]

It sounds a bit like a proposal? At the moment I think this is behaving as expected.
It sounds like something I mentioned in #14671 (comment) and I was wondering if it would be worth opening a proposal for those different ranges, or if it is better to keep it as simple and limited as it is right now because maybe they would give more opportunities for logic errors to work unexpectedly.

[nektro]

I would definitely not expect the types to be padded out to usize, but i would expect this program to print 0 with no issue. this definitely seems like a bug indeed

edit: didnt realize it was going from 1 to 0

[andrewrk]

This is working as designed. You can't have a negative length. Note that if you make them const, you get a compile error:

test.zig:6:15: error: overflow of integer type 'u32' with value '-1'
    for (start..end) |x| {
         ~~~~~^~~~~

You also can't slice this way:

const std = @import("std");

pub fn main() void {
    const hello = "hello";
    const start: u32 = 1;
    const end: u32 = 0;
    const slice = hello[start..end];
    _ = slice;
}

test.zig:7:25: error: start index 1 is larger than end index 0
    const slice = hello[start..end];
                        ^~~~~

with runtime known values:

thread 2084384 panic: start index 1 is larger than end index 0
/home/andy/dev/zig/build-release/test.zig:7:24: 0x20b45a in main (test)
    const slice = hello[start..end];
                       ^