A typo in "const" keyword causes "error: expected ',' after field" message

[Durobot]

Zig Version

0.11.0-dev.2477+2ee328995

Steps to Reproduce and Observed Output

Try to compile the following code:

cost std = @import("std");

pub fn main() void
{
    std.debug.print("Hello, Zig!\n", .{});
}

The following error message is shown:

cost_comp_error.zig:1:6: error: expected ',' after field
cost std = @import("std");
     ^~~

Expected Output

Expected to see an error message stating that cost is an unknown identifier,
or, since .zig files are structs, and the compiler probably considered cost to be the name of the field, "missing : between field cost and type std", and/or "field cost of unknown type std".

[mlugg]

or, since .zig files are structs, and the compiler probably considered cost to be the name of the field, "missing : between field cost and type std"

This error message is happening because the file is actually being parsed as a tuple type (since tuples are basically just structs), with the first field having type cost. I think it'd be reasonable to disallow files from being tuples, since you can't have declarations on tuples so it seems quite useless; however this issue would still remain on actual struct definitions. Perhaps this should be made a more general error message such as expected field or declaration.

[Durobot]

.. with the first field having type cost.

You mean, the first field is named cost?

I think it'd be reasonable to disallow files from being tuples

Parts of the standard library rely on this, as far as I can tell, e.g. Allocator.zig -

const Allocator = @This();
. . .
ptr: *anyopaque,
vtable: *const VTable,