librustc: Implement "&mut [T]" as an expression

src/librustc/middle/const_eval.rs

@@ -103,7 +103,8 @@ fn classify(e: @expr,
                       ast::expr_vstore_slice => classify(e, def_map, tcx),
                       ast::expr_vstore_uniq |
                       ast::expr_vstore_box |
-                      ast::expr_vstore_mut_box => non_const
+                      ast::expr_vstore_mut_box |
+                      ast::expr_vstore_mut_slice => non_const
                   }
               }
 

src/librustc/middle/trans/expr.rs

@@ -527,7 +527,8 @@ fn trans_rvalue_dps_unadjusted(bcx: block, expr: @ast::expr,
         ast::expr_lit(@{node: ast::lit_str(s), _}) => {
             return tvec::trans_lit_str(bcx, expr, s, dest);
         }
-        ast::expr_vstore(contents, ast::expr_vstore_slice) => {
+        ast::expr_vstore(contents, ast::expr_vstore_slice) |
+        ast::expr_vstore(contents, ast::expr_vstore_mut_slice) => {
             return tvec::trans_slice_vstore(bcx, expr, contents, dest);
         }
         ast::expr_vstore(contents, ast::expr_vstore_fixed(_)) => {

src/librustc/middle/ty.rs

@@ -3099,6 +3099,7 @@ fn expr_kind(tcx: ctxt,
         ast::expr_repeat(*) |
         ast::expr_lit(@{node: lit_str(_), _}) |
         ast::expr_vstore(_, ast::expr_vstore_slice) |
+        ast::expr_vstore(_, ast::expr_vstore_mut_slice) |
         ast::expr_vstore(_, ast::expr_vstore_fixed(_)) |
         ast::expr_vec(*) => {
             RvalueDpsExpr

src/librustc/middle/typeck/check/mod.rs

@@ -1804,7 +1804,9 @@ fn check_expr_with_unifier(fcx: @fn_ctxt,
             let tt = ast_expr_vstore_to_vstore(fcx, ev, args.len(), vst);
             let mutability;
             match vst {
-                ast::expr_vstore_mut_box => mutability = ast::m_mutbl,
+                ast::expr_vstore_mut_box | ast::expr_vstore_mut_slice => {
+                    mutability = ast::m_mutbl
+                }
                 _ => mutability = mutbl
             }
             let t: ty::t = fcx.infcx().next_ty_var();
@@ -2823,7 +2825,7 @@ fn ast_expr_vstore_to_vstore(fcx: @fn_ctxt, e: @ast::expr, n: uint,
         }
         ast::expr_vstore_uniq => ty::vstore_uniq,
         ast::expr_vstore_box | ast::expr_vstore_mut_box => ty::vstore_box,
-        ast::expr_vstore_slice => {
+        ast::expr_vstore_slice | ast::expr_vstore_mut_slice => {
             let r = fcx.infcx().next_region_var(e.span, e.id);
             ty::vstore_slice(r)
         }

src/libsyntax/ast.rs

@@ -441,7 +441,8 @@ enum expr_vstore {
     expr_vstore_uniq,                  // ~[1,2,3,4]
     expr_vstore_box,                   // @[1,2,3,4]
     expr_vstore_mut_box,               // @mut [1,2,3,4]
-    expr_vstore_slice                  // &[1,2,3,4]
+    expr_vstore_slice,                 // &[1,2,3,4]
+    expr_vstore_mut_slice,             // &mut [1,2,3,4]
 }
 
 pure fn is_blockish(p: ast::Proto) -> bool {

src/libsyntax/parse/parser.rs

@@ -37,7 +37,7 @@ use ast::{_mod, add, arg, arm, attribute,
              expr_method_call, expr_paren, expr_path, expr_rec, expr_repeat,
              expr_ret, expr_swap, expr_struct, expr_tup, expr_unary,
              expr_unary_move, expr_vec, expr_vstore, expr_vstore_mut_box,
-             expr_while, extern_fn, field, fn_decl,
+             expr_vstore_mut_slice, expr_while, extern_fn, field, fn_decl,
              foreign_item, foreign_item_const, foreign_item_fn, foreign_mod,
              ident, impure_fn, infer, inherited,
              item, item_, item_class, item_const, item_enum, item_fn,
@@ -1456,6 +1456,9 @@ impl Parser {
                   if m == m_imm => {
                     expr_vstore(e, expr_vstore_slice)
                   }
+                  expr_vec(*) if m == m_mutbl => {
+                    expr_vstore(e, expr_vstore_mut_slice)
+                  }
                   _ => expr_addr_of(m, e)
                 };
               }

src/libsyntax/print/pprust.rs

@@ -1049,6 +1049,10 @@ fn print_expr_vstore(s: ps, t: ast::expr_vstore) {
         word(s.s, ~"mut");
       }
       ast::expr_vstore_slice => word(s.s, ~"&"),
+      ast::expr_vstore_mut_slice => {
+        word(s.s, ~"&");
+        word(s.s, ~"mut");
+      }
     }
 }
 

src/test/run-pass/mut-vstore-expr.rs

@@ -0,0 +1,4 @@
+fn main() {
+    let x: &mut [int] = &mut [ 1, 2, 3 ];
+}
+