Create correct drop glue for istrs. Issue #855

src/comp/middle/trans.rs

@@ -1426,6 +1426,10 @@ fn make_drop_glue(cx: &@block_ctxt, v0: ValueRef, t: ty::t) {
             let rslt = iter_structural_ty(cx, v1, t, drop_ty);
             maybe_free_ivec_heap_part(rslt.bcx, v1, tm.ty)
           }
+          ty::ty_istr. {
+            maybe_free_ivec_heap_part(cx, v0,
+                                      ty::mk_mach(ccx.tcx, ast::ty_u8))
+          }
           ty::ty_box(_) { decr_refcnt_maybe_free(cx, v0, v0, t) }
           ty::ty_uniq(_) { trans_shared_free(cx, cx.build.Load(v0)) }
           ty::ty_obj(_) {

src/test/run-pass/istr.rs

@@ -11,7 +11,13 @@ fn test_heap_lit() {
     ~"a big string";
 }
 
+fn test_heap_assign() {
+    let s: istr;
+    s = ~"AAAA";
+}
+
 fn main() {
     test_stack_assign();
     test_heap_lit();
+    test_heap_assign();
 }