import std.stdio;

​

@safe:

​

struct ScopeBuffer

{

    this(char[4] init)

    {

        this.buf = init;

    }

    // The bug is that `inout` implies `return` on `this`.

    // See https://github.com/dlang/dmd/blob/2dc5b15d1949148d460e8c809dd878e6dec8dfa3/src/dmd/func.d#L511-L513

    inout(char)[] opSlice(size_t lower, size_t upper) inout

    do

    {

        return buf[lower .. upper]; //BUG: compiler error should be emitted here

    }

    char[4] buf;

}

​

char[] fun()

{

    char[4] buf = "abcd";

    auto sb = ScopeBuffer(buf);

    return sb[0..2];

}

​

void main()

{

    auto s = fun();

    writeln(s);

}