```zig
// a.zig
struct Foo {
    a: u32,
};
```

before:
```
a.zig:1:1: error: expected test, comptime, var decl, or container field, found 'struct'
struct Foo {
^
```
after:
```
a.zig:1:8: error: 'struct Foo' is invalid
struct Foo {
       ^
a.zig:1:8: note: to declare a container do 'const Foo = struct'
struct Foo {
       ^
```