Re: Compiler bug or incorrect usage for pointer of Struct?

[Temtaime via Digitalmars-d]

On Sunday, 14 January 2018 at 04:02:09 UTC, Heromyth wrote:
On Saturday, 13 January 2018 at 14:11:23 UTC, H. S. Teoh wrote:
On Sat, Jan 13, 2018 at 12:22:17PM +0000, Heromyth via 
Digitalmars-d wrote: [...]
auto writerFor(OutRange)(auto ref OutRange outRange)
{
    auto res = Writer!(OutRange)();
    res.setSink(outRange);
    return res;
}
struct Writer(OutRange)
{
    private OutRange* output;

    void setSink(ref OutRange output)
    {
        this.output = &output;
[...]

Here's the bug.  `output` refers to a local variable 
(parameter) in
writerFor(), which goes out of scope after writerFor() exits, 
so
this.output becomes a dangling pointer.


T

I have another test. It runs whithout any error. Here it is:

import std.stdio;

void main()
{
        Tester tester = new Tester(buildWriter());
        tester.run("It's OK");
}

struct StringWriter
{
        void put(string s)
        {
                writeln(s);
        }
}

StringWriter buildWriter()
{
        return StringWriter();
}

class Tester
{
        private StringWriter* writer;

        this(StringWriter w)
        {
                writer = &w;
                writer.put("ok");
        }

        void run(string m)
        {
                writer.put(m);
        }
}

https://run.dlang.io/is/RUHtqK
It's not ok dude
It runs because you don't use any variable inside the struct and 
because struct members are simple functions with hidden parameter