Compiler bug or incorrect usage for pointer of Struct?

[Temtaime]

On Saturday, 13 January 2018 at 12:22:17 UTC, Heromyth wrote:
> When executing the test code, it will exit abnormally. It seems 
> *this.output* is pointing a free memory when executing 
> *writer.write(dom)*.
>
> I'm not sure whether there is a bug in the compiler. If it is, 
> I can file a bug. If not, somebody can tell me how to fix this.
>
> Thanks!
>
> Here is my test code (You can test it in 
> https://run.dlang.io/is/0OPBVI):
>
> ==============================
> import std.stdio;
>
> void main()
> {
>     bugTest();
> }
>
> // This code is stripped from 
> https://github.com/Kozzi11/experimental.xml/blob/master/source/std/experimental/xml/writer.d
> void bugTest()
> {
>     string dom = "XML DOM";
>
>     auto file = File("catalogue.xml", "w");
>
>     // It's OK
>     // auto textWriter = file.lockingTextWriter;
>     // textWriter.writerFor.write(dom);
>
>     // There's a bug
>     auto writer = writerFor(file.lockingTextWriter);
>     writer.write(dom);
>
>     file.close();
> }
>
> 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;
>         writeln("in setSink: ", this.output);
>     }
>
>     // void setSink(typeof(output) output)
>     // {
>     // 	this.output = output;
>     // }
>
>     void write(string s)
>     {
>         writeln("in write: ", output);
>         output.put(s);
>     }
> }

It's your bug.
file.lockingTextWriter does not return a reference.
It is passed to writerFor as a copy on the stack and in setSink 
you get a pointer of a stack variable that gets killed after 
writerFor returns.