RFC for allowing macros in all ident positions

active/0053-ident-macros.md

@@ -0,0 +1,51 @@
+- Start Date: 2014-08-28
+- RFC PR: (leave this empty)
+- Rust Issue: (leave this empty)
+
+# Summary
+
+Macros which resolve to idents should be usable in all positions that expect idents, including function/struct/enum names in definitions, et cetera.
+Currently they can only be used as variable names.
+
+# Motivation
+
+This will allow for creating better macros which resolve to functions. For example:
+
+```
+macro_rules! make_setter(
+    ( $attr:ident ) => (
+        fn concat_idents!(set_,$attr) (&self) -> u32 {
+            self.$attr
+        }
+    );
+)
+```
+
+can be created to generate setters just by calling `make_setter(foo)` (which will create `set_foo()`)
+
+
+Currently, using macros in this manner will lead to errors like
+
+```
+test.rs:1:17: 1:18 error: expected `(` but found `!`
+test.rs:1 fn concat_idents!(Foo, Bar) () {
+                          ^
+```
+
+See also: https://github.com/rust-lang/rust/issues/13294
+
+# Detailed design
+
+This will probably require converting [`ast::Ident`](http://doc.rust-lang.org/master/syntax/ast/struct.Ident.html) to an enum allowing for a `NamedIdent` vs `MacroIdent` duality.
+
+# Drawbacks
+
+None that I see
+
+# Alternatives
+
+Suggestions welcome
+
+# Unresolved questions
+
+I'm rather unsure about the implementation.