无法从任意长度的字符串数组中释放内存字符串

我想编写一个函数来读取文本文件，并将其行作为字符串数组返回以供进一步处理。

为此，我试图正确处理长度为 N 的字符串数组，其中 N 在运行时确定。

我有这个基本示例，其中有一个长度为 2 的硬编码数组。它运行良好，并且没有报告任何泄漏：

const std = @import("std");
const stdout = std.io.getStdOut().writer();
var gpa = std.heap.GeneralPurposeAllocator(.{}){};

pub fn main() !void {
    const alloc = gpa.allocator();
    defer _ = gpa.deinit();

    const names = try getNames(alloc);
    defer destroyNames(alloc, names);

    for(names) |name| {
        try stdout.print("Hello {s}\n", .{name});
    }
}


fn destroyNames(alloc:std.mem.Allocator, names:*[2][]const u8) void {
    for(names) |name| {
        // Correctly frees the '[]const u8'
        alloc.free(name);
    }
    _ = alloc.destroy(names);
}


fn getNames(alloc:std.mem.Allocator) !*[2][]const u8 {
    const names = [_][]const u8{"Alix", "Bub"};

    const new_names = try alloc.create([2][]const u8);
    const title = "Prof";

    for(names, 0..) |name, i| {
        new_names[i] = try std.fmt.allocPrint(alloc, "{s} {s}", .{title, name} );
    }

    return new_names;
}

对此感到满意，我继续移动一些东西。下面的代码运行，但在延迟destroyNames操作上失败

const std = @import("std");
const stdout = std.io.getStdOut().writer();
var gpa = std.heap.GeneralPurposeAllocator(.{}){};

pub fn main() !void {
    const alloc = gpa.allocator();
    defer _ = gpa.deinit();

    const names = try getNames(alloc);
    defer destroyNames(alloc, names);

    for(names.*) |name| {
        try stdout.print("Hello {s}\n", .{name});
    }
}


fn destroyNames(alloc:std.mem.Allocator, names:*[][]const u8) void {
    for(names.*) |name| {
        // ERROR - core dumps here...!
        // Cannot properly free a '[]const u8' supplied like this
        alloc.free(name);
    }
    _ = alloc.destroy(names);
}


fn getNames(alloc:std.mem.Allocator) !*[][]const u8 {
    // Stand-in. Hypothetically, read from a N-line file...
    const names = [_][]const u8{"Alix", "Bub"};

    var new_names:[][]const u8 = undefined;
    new_names = try alloc.create([names.len][]const u8);
    const title = "Prof";

    for(names, 0..) |name, i| {
        new_names[i] = try std.fmt.allocPrint(alloc, "{s} {s}", .{title, name} );
    }

    return &new_names;
}

运行结果

$ zig run length-general.zig 
Hello Prof Alix
Hello Prof Bub
General protection exception (no address available)
/home/tai/.local/var/zig/zig-linux-x86_64-0.14.0-dev.1366+d997ddaa1/lib/compiler_rt/memset.zig:19:14: 0x10f7f10 in memset (compiler_rt)
            d[0] = c;
             ^
/home/tai/.local/var/zig/zig-linux-x86_64-0.14.0-dev.1366+d997ddaa1/lib/std/mem/Allocator.zig:313:26: 0x1040e57 in free__anon_3449 (length-general)
    @memset(non_const_ptr[0..bytes_len], undefined);
                         ^
/home/tai/scratch-zig/length-general.zig:26:19: 0x103bacc in destroyNames (length-general)
        alloc.free(name);
                  ^
/home/tai/scratch-zig/length-general.zig:14:23: 0x103b59c in main (length-general)
    defer destroyNames(alloc, names);
                      ^
/home/tai/.local/var/zig/zig-linux-x86_64-0.14.0-dev.1366+d997ddaa1/lib/std/start.zig:615:37: 0x103ad2f in posixCallMainAndExit (length-general)
            const result = root.main() catch |err| {
                                    ^
/home/tai/.local/var/zig/zig-linux-x86_64-0.14.0-dev.1366+d997ddaa1/lib/std/start.zig:250:5: 0x103a90f in _start (length-general)
    asm volatile (switch (native_arch) {
    ^
???:?:?: 0x0 in ??? (???)
Aborted (core dumped)

作为一个尝试检查，我确实尝试alloc.free(name.*)在这两个例子中，并且都报告了相同的error: index syntax required for slice type '[]const u8'结果，这对我来说意味着它们确实都收到了相同的结果[]const u8

我该如何修复这些错误？