module test;

struct Foo { }
void main()
{
    Foo x;
    int Foo;
    Foo y;  // Error: Foo is used as a type
}

Compare the above to this:

module a;
int Foo;

module b;
struct Foo { }

module main;

import a;
import b;

void main() {
    Foo m;
}

main.d(7): Error: a.Foo at a.d(2) conflicts with b.Foo at b.d(2)
main.d(7): Error: Foo is used as a type

The first code example could instead output:
test.d(8): Error: test.Foo at test.d(3) conflicts with test.Foo at test.d(7)
test.d(8): Error: Foo is used as a type