behavior and documentation of right shift on signed integers differs

[scottredig]

Zig Version

0.14.0-dev.1913+7b8fc18c6

Steps to Reproduce and Observed Behavior

When doing a right shift on a negative signed integer, 1 is shifted in for the missing significant digits, this is the behavior my code needs:

const std = @import("std");

pub fn main() void {
    const value: i8 = -5;
    const value_bits: u8 = @bitCast(value);

    const shifted = value >> 1;
    const shifted_bits: u8 = @bitCast(shifted);
    std.debug.print("Value:   {b} {d}\n", .{ value_bits, value });
    std.debug.print("Shifted: {b} {d}\n", .{ shifted_bits, shifted });
}

Produces this result:

Value:   11111011 -5
Shifted: 11111101 -3

However, language reference states

Bit Shift Right

Moves all bits to the right, inserting zeroes at the most-significant bit.

Expected Behavior

The language reference state the correct behavior, assuming that it is the intended behavior.

[rohlem]

Related discussion of distinguishing logical (= insert 0) from arithmetic (= sign-extending) shifts: #20367