Zig fmt doesn't align vertically on trailing comma

[kristoff-it]

Zig Version

0.13.0

Steps to Reproduce and Observed Behavior

fn version(b: anytype) []const u8 {
    const git_describe = std.mem.trim(
        u8,
        b.run(&[_][]const u8{"git", "-C", b.build_root.path.?, "describe", "--match", "*.*.*", "--tags",
             }),
        " \n\r",
    );
}

Expected Behavior

On format the list of arguments should be aligned vertically because of the trailing comma but instead it all stays on one line.

Unless this is a peculiar corner-case of more-than-one-item-per-line formatting, it seems a bug.

Removing the comma, formatting, and then adding it back restored the expected behavior (because the first save changes the location of }),.

[castholm]

This is not a bug, zig fmt has special rules for array inits and tries to format them like tables. What you end up with in your repro is a table with 7 columns and 1 row. But if you for example instead first manually format your code like this

fn version(b: anytype) []const u8 {
    const git_describe = std.mem.trim(
        u8,
        b.run(&[_][]const u8{"git", "-C", b.build_root.path.?,
        "describe", "--match", "*.*.*", "--tags", }),
        " \n\r",
    );
}

before invoking zig fmt, you end up with a table with 3 columns and 3 rows:

fn version(b: anytype) []const u8 {
    const git_describe = std.mem.trim(
        u8,
        b.run(&[_][]const u8{
            "git",      "-C",      b.build_root.path.?,
            "describe", "--match", "*.*.*",
            "--tags",
        }),
        " \n\r",
    );
}

However, it should be noted that this special handling is a little awkward and is the reason that // zig fmt: off does not work in array inits. It has been suggested that this special handling should be removed in favor of manual alignment with // zig fmt: off (#10418 (comment)), or expanded upon as part of #17145.