boost crowd.

[Alexey Veselovsky]

ok. I just removed from test.di all non public entities.

// D import file generated from 'test.d'
module test;
public
{
    void foo();

    struct Boo
    {
        public
        {
            void boo();
        }
    }
}

Now, let's build it:
$ dmd test.di test.d main.d
test.d: Error: module test from file test.d conflicts with another
module test from file test.di

di file not specification, but just another version of implementation?

ok. let's separate build.

$ dmd -c test.d
$ dmd main.d test.di
main.d(7): Error: no property 'S' for type 'Boo'
main.d(7): Error: Boo.S is used as a type
main.d(8): Error: undefined identifier HelperStruct

It seem like ok. Expected error. We fix it, and everybody happy. But
after years, someone changes test.d:

module test;

public {
    void foo() {foo_helper();}

    struct Boo
    {
    public:
        void booBar() {S ss; foo_helper();} // <---- method was renamed
    private:
        struct S {};
    }
}

private {
    struct HelperStruct {};
    void foo_helper() {HelperStruct s;}
}

He rename method, but forgot to change test.di. Let's build it:
$ dmd -c test.d
$ dmd main.d test.di
Undefined symbols for architecture i386:
  "_D4test3Boo3booMFZv", referenced from:
      __Dmain in main.o
  "_D4test3fooFZv", referenced from:
      __Dmain in main.o
ld: symbol(s) not found for architecture i386
collect2: ld returned 1 exit status

Oops. No compilation error. Only linker error. Welcome back to C!

Compiler doesn't know anything about "specification" files. So, he
did't check specification&implementation conformance.