RFC: remove virtual structs

active/0000-remove-virtual-structs.md

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+- Start Date: (fill me in with today's date, 2014-09-30)
+- RFC PR: (leave this empty)
+- Rust Issue: (leave this empty)
+
+# Summary
+
+Removes the "virtual struct" (aka struct inheritance) feature, which
+is currently feature gated.
+
+# Motivation
+
+Virtual structs were added experimentally prior to the RFC process as
+a way of inheriting fields from one struct when defining a new struct.
+
+The feature was introduced and remains behind a feature gate.
+
+The motivations for removing this feature altogether are:
+
+1. The feature is likely to be replaced by a more general mechanism,
+   as part of the need to address hierarchies such as the DOM, ASTs,
+   and so on. See
+   [this post](http://discuss.rust-lang.org/t/summary-of-efficient-inheritance-rfcs/494/43)
+   for some recent discussion.
+
+2. The implementation is somewhat buggy and incomplete, and the
+   feature is not well-documented.
+
+3. Although it's behind a feature gate, keeping the feature around is
+   still a maintenance burden.
+
+# Detailed design
+
+Remove the implementation and feature gate for virtual structs.
+
+Retain the `virtual` keyword as reserved for possible future use.
+
+# Drawbacks
+
+The language will no longer offer any built-in mechanism for avoiding
+repetition of struct fields. Macros offer a reasonable workaround
+until a more general mechanism is added.
+
+# Unresolved questions
+
+None known.