Add take glue for unique boxes

Closes #962
Issue #409

Author: brson

src/comp/middle/trans.rs

@@ -1295,6 +1295,9 @@ fn make_take_glue(cx: @block_ctxt, v: ValueRef, t: ty::t) {
     // NB: v is an *alias* of type t here, not a direct value.
     if ty::type_is_boxed(bcx_tcx(bcx), t) {
         bcx = incr_refcnt_of_boxed(bcx, Load(bcx, v));
+    } else if ty::type_is_unique_box(bcx_tcx(bcx), t) {
+        check trans_uniq::type_is_unique_box(bcx, t);
+        bcx = trans_uniq::duplicate(bcx, v, t);
     } else if ty::type_is_structural(bcx_tcx(bcx), t) {
         bcx = iter_structural_ty(bcx, v, t, take_ty);
     } else if ty::type_is_vec(bcx_tcx(bcx), t) {

src/comp/middle/trans_uniq.rs

@@ -15,7 +15,8 @@ import trans::{
     new_sub_block_ctxt
 };
 
-export trans_uniq, make_free_glue, type_is_unique_box, copy_val, autoderef;
+export trans_uniq, make_free_glue, type_is_unique_box, copy_val,
+autoderef, duplicate;
 
 pure fn type_is_unique_box(bcx: @block_ctxt, ty: ty::t) -> bool {
     unchecked {
@@ -106,4 +107,17 @@ fn autoderef(bcx: @block_ctxt, v: ValueRef, t: ty::t)
 
     let content_ty = content_ty(bcx, t);
     ret {v: v, t: content_ty};
+}
+
+fn duplicate(bcx: @block_ctxt, v: ValueRef, t: ty::t)
+    : type_is_unique_box(bcx, t) -> @block_ctxt {
+
+    let content_ty = content_ty(bcx, t);
+    let {bcx, val: llptr} = alloc_uniq(bcx, t);
+
+    let src = Load(bcx, Load(bcx, v));
+    let dst = llptr;
+    let bcx = trans::copy_val(bcx, INIT, dst, src, content_ty);
+    Store(bcx, dst, v);
+    ret bcx;
 }

src/test/run-pass/unique-assign-generic.rs

@@ -0,0 +1,11 @@
+fn f<@T>(t: T) -> T {
+    let t1 = t;
+    t1
+}
+
+fn main() {
+    let t = f(~100);
+    assert t == ~100;
+    let t = f(~@[100]);
+    assert t == ~@[100];
+}