C Backend Miscompiles With static void const Incomplete Type

[Bud-ro]

Zig Version

0.14.0-dev.2384+cbc05e0b1

Steps to Reproduce and Observed Behavior

OS: Windows 10

When using the C-backend I run into an issue of a static void const type being generated, which leads to a compile error in GCC. A minimized example can be found on my branch: https://github.com/Bud-ro/zig-pub-sub/tree/error_reproduction, code pasted for convenience:

const std = @import("std");

const Erd = struct {
    T: type,
    owner: ErdOwner,

    pub const ErdOwner = enum {
        Ram,
        Indirect,
    };
};

pub const ErdDefinitions = struct {
    // zig fmt: off
    application_version:  Erd = .{ .T = u32,   .owner = .Ram      },
    some_bool:            Erd = .{ .T = bool,  .owner = .Ram      },
    unaligned_u16:        Erd = .{ .T = u16,   .owner = .Ram      },
    always_42:            Erd = .{ .T = u16,   .owner = .Indirect },
    pointer_to_something: Erd = .{ .T = ?*u16, .owner = .Ram      },
    another_erd_plus_one: Erd = .{ .T = u16,   .owner = .Indirect },
    // zig fmt: on
};

const erds = ErdDefinitions{};

pub export fn main() void {
    std.log.err("some_bool has type {}", .{erds.some_bool.T});
}

When this is compiled with zig build-exe -target x86_64-linux-gnu -OReleaseSmall -ofmt=c ./src/example_repro.zig -femit-bin=".\zig-out\bin\main.c" and put through GCC (inside WSL, this was necessary because the C-backend doesn't support Windows to my knowledge) the output is the following:

$ gcc --version
gcc (Ubuntu 9.4.0-1ubuntu1~20.04.1) 9.4.0
$ gcc ./zig-out/bin/main.c
./zig-out/bin/main.c:697:19: error: variable or field ‘example_repro_erds__227’ declared void
  697 | static void const example_repro_erds__227;
      |                   ^~~~~~~~~~~~~~~~~~~~~~~
./zig-out/bin/main.c:4339:19: error: variable or field ‘example_repro_erds__227’ declared void
 4339 | static void const example_repro_erds__227 = {};
      |                   ^~~~~~~~~~~~~~~~~~~~~~~
./zig-out/bin/main.c:4339:45: error: empty scalar initializer
 4339 | static void const example_repro_erds__227 = {};

Removing that ErdOwner enum field and definition leads to a C file free of this empty type.

Expected Behavior

Expected behavior is for types only used at comptime to not have code generation in the C-backend. Further, it is expected that no incomplete types would be generated by the C-backend.