[Issue 17968] New: object initializer for auto function not included when seen through 2 libraries

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=17968

          Issue ID: 17968
           Summary: object initializer for auto function not included when
                    seen through 2 libraries
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Keywords: link-failure
          Severity: normal
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: schveiguy at yahoo.com

I need to reduce this more. But I can't figure out easily what the trigger is.
It has something to do with the auto return.

Just wanting to put a bug in place so it's not forgotten.

Here is the gist of the situation:

I have one library that depends on another. In the first library I have a
function like so:

auto openDev(int fd)
{
   return ioObject(File(fd));
}

ioObject is from another library that looks like this:

IOObject!IO ioObject(IO)(IO io)
{
    return new IOObject!IO(io.move);
}

Where IOObject is a templated class.

In a program I am compiling, I have a statement that uses openDev(0).

If I compile this, I get a missing symbol, which is this:

_D50TypeInfo_xC3std2io__T8IOObjectTSQvQt4file4FileZQBa6__initZ

This is the initializer for the IOObject!File, that the ioObject is
instantiating. However, it is never instantiated in either library.

If I change the auto return to returning IOObject!File, it links and compiles.
At that point, the object file of the executable (not either of the libraries)
*defines* the symbol (in one case, nm says the symbol is undefined, in the
successful case, it says it's defined). I'm not sure what the difference is,
but clearly it should define it either way, it shouldn't look to the libraries
to define it.

I tried reducing to a simple 2-library solution with some simplified code. This
did not exhibit the problem. The libraries in question don't compile on
anything earlier than 2.076.0, so I am going to work around these issues to see
if this ever worked.

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