sentinel-terminated slice has wrong length after @alignCast / coercion from array pointer

[ssmid]

Zig Version

zig-0.15.0.1184+c41ac8f19

Steps to Reproduce and Observed Behavior

main.zig:

const std = @import("std");

const shader_code: *const [4:0]u8 = @embedFile("test.txt");

pub fn main() void {
        std.debug.print("{d}\n", .{shader_code.len});
        createShader(@alignCast(shader_code));
}

fn createShader(data: [:0]align(4) const u8) void {
        std.debug.print("{d}\n", .{data.len});
}

(note, that createShader() takes a non-terminated slice)
(EDIT: doesn't matter)

test.txt (no trailing line break):

1234

$ zig run main.zig
4
5

Expected Behavior

$ zig run main.zig
4
4

Even after @alignCast, the slice's length should be 4.

This was the case in zig 0.14.

[xdBronch]

this was introduced in #23919 i believe cc @mlugg, it calls abiSize which includes the sentinel in the array and doesnt account for it in the length
https://github.com/ziglang/zig/blob/bb71a18ede1f976ad6d6bb7e84b88f0edc7d30e9/src/Sema.zig#L22511
im not sure if the fix is as simple as subtracting 1 if theres a sentinel so i'll just leave this here for now :p