[Issue 18426] New: Conversion from Tuple with named fields to Tuple without named fields should work during compilation

[d-bugmail at puremagic.com]

https://issues.dlang.org/show_bug.cgi?id=18426

          Issue ID: 18426
           Summary: Conversion from Tuple with named fields to Tuple
                    without named fields should work during compilation
           Product: D
           Version: D2
          Hardware: x86_64
                OS: Linux
            Status: NEW
          Severity: enhancement
          Priority: P1
         Component: dmd
          Assignee: nobody at puremagic.com
          Reporter: andrei at erdani.com

Refer to
https://github.com/dlang/phobos/commit/8becc70da790826bccec734d40021dd7ff22f485.

Currently we implement the correct subtyping by means of a cast, which does not
work during compilation.

A better implementation would be to have the Tuple with named fields use the
Tuple with no named fields as its only member variable; then, "alias this"
needs to simply return a reference to that member.

--