[Issue 2206] New: unnamed template mixin of class inside function or class has incorrect classinfo and mangleof

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=2206

           Summary: unnamed template mixin of class inside function or class
                    has incorrect classinfo and mangleof
           Product: D
           Version: 1.029
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Keywords: wrong-code
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla at digitalmars.com
        ReportedBy: kamm-removethis at incasoftware.de


Test:
--
template T() {
  class C {}
}

void main()
{
  mixin T!(); // using a named mixin here fixes it

  pragma(msg, T!().C.mangleof);
  pragma(msg, C.mangleof); // incorrectly outputs the same as above

  assert(T!().C.classinfo !is C.classinfo); // fails
  assert(T!().C.mangleof != C.mangleof); // fails
}
--
The types of T!().C and main.C are clearly different as the nested one carries
an additional context pointer. This means that allocation relying on
classinfo.init.length should be wrong too.

In the frontend the types are initially different and only merged into a single
type during semantic. To be specific, Type::mangle unifies them as toDecoBuffer
yields the same result for both.

Maybe this could be fixed by adding a TemplateMixin::mangle overload. This
frontend bug causes some template-mixin related bugs in LLVMDC that seem to be
worked around somehow in DMD.


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