fix drop of fat ptrs

Author: nikomatsakis

src/librustc_trans/trans/mir/operand.rs

@@ -245,8 +245,7 @@ impl<'bcx, 'tcx> MirContext<'bcx, 'tcx> {
                 }
                 let lvalue = self.trans_lvalue(bcx, lvalue);
                 let ty = lvalue.ty.to_ty(bcx.tcx());
-                if !glue::type_needs_drop(bcx.tcx(), ty) ||
-                    common::type_is_fat_ptr(bcx.tcx(), ty) {
+                if !glue::type_needs_drop(bcx.tcx(), ty) {
                     return
                 } else {
                     drop::drop_fill(bcx, lvalue.llval, ty);

src/test/run-pass/mir_fat_ptr_drop.rs

@@ -0,0 +1,39 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// test that ordinary fat pointer operations work.
+
+#![feature(braced_empty_structs)]
+#![feature(rustc_attrs)]
+
+use std::sync::atomic;
+use std::sync::atomic::Ordering::SeqCst;
+
+static COUNTER: atomic::AtomicUsize = atomic::ATOMIC_USIZE_INIT;
+
+struct DropMe {
+}
+
+impl Drop for DropMe {
+    fn drop(&mut self) {
+        COUNTER.fetch_add(1, SeqCst);
+    }
+}
+
+#[rustc_mir]
+fn fat_ptr_move_then_drop(a: Box<[DropMe]>) {
+    let b = a;
+}
+
+fn main() {
+    let a: Box<[DropMe]> = Box::new([DropMe { }]);
+    fat_ptr_move_then_drop(a);
+    assert_eq!(COUNTER.load(SeqCst), 1);
+}