auto merge of #9989 : luqmana/rust/mut-everywhere, r=alexcrichton

Author: bors

doc/rust.md

@@ -3395,16 +3395,23 @@ a [temporary](#lvalues-rvalues-and-temporaries), or a local variable.
 A _local variable_ (or *stack-local* allocation) holds a value directly,
 allocated within the stack's memory. The value is a part of the stack frame.
 
-Local variables are immutable unless declared with `let mut`.  The
-`mut` keyword applies to all local variables declared within that
-declaration (so `let mut (x, y) = ...` declares two mutable variables, `x` and
-`y`).
+Local variables are immutable unless declared otherwise like: `let mut x = ...`.
 
 Function parameters are immutable unless declared with `mut`. The
 `mut` keyword applies only to the following parameter (so `|mut x, y|`
 and `fn f(mut x: ~int, y: ~int)` declare one mutable variable `x` and
 one immutable variable `y`).
 
+Methods that take either `self` or `~self` can optionally place them in a
+mutable slot by prefixing them with `mut` (similar to regular arguments):
+
+~~~
+trait Changer {
+    fn change(mut self) -> Self;
+    fn modify(mut ~self) -> ~Self;
+}
+~~~
+
 Local variables are not initialized when allocated; the entire frame worth of
 local variables are allocated at once, on frame-entry, in an uninitialized
 state. Subsequent statements within a function may or may not initialize the

src/librustc/metadata/decoder.rs

@@ -975,9 +975,9 @@ fn get_explicit_self(item: ebml::Doc) -> ast::explicit_self_ {
     let explicit_self_kind = string[0];
     match explicit_self_kind as char {
         's' => { return ast::sty_static; }
-        'v' => { return ast::sty_value; }
+        'v' => { return ast::sty_value(get_mutability(string[1])); }
         '@' => { return ast::sty_box(get_mutability(string[1])); }
-        '~' => { return ast::sty_uniq; }
+        '~' => { return ast::sty_uniq(get_mutability(string[1])); }
         '&' => {
             // FIXME(#4846) expl. region
             return ast::sty_region(None, get_mutability(string[1]));

src/librustc/metadata/encoder.rs

@@ -662,8 +662,9 @@ fn encode_explicit_self(ebml_w: &mut writer::Encoder, explicit_self: ast::explic
         sty_static => {
             ebml_w.writer.write(&[ 's' as u8 ]);
         }
-        sty_value => {
+        sty_value(m) => {
             ebml_w.writer.write(&[ 'v' as u8 ]);
+            encode_mutability(ebml_w, m);
         }
         sty_region(_, m) => {
             // FIXME(#4846) encode custom lifetime
@@ -674,8 +675,9 @@ fn encode_explicit_self(ebml_w: &mut writer::Encoder, explicit_self: ast::explic
             ebml_w.writer.write(&[ '@' as u8 ]);
             encode_mutability(ebml_w, m);
         }
-        sty_uniq => {
+        sty_uniq(m) => {
             ebml_w.writer.write(&[ '~' as u8 ]);
+            encode_mutability(ebml_w, m);
         }
     }
 

src/librustc/middle/astencode.rs

@@ -410,7 +410,7 @@ impl tr for ast::Def {
             ast::DefMethod(did0.tr(xcx), did1.map(|did1| did1.tr(xcx)))
           }
           ast::DefSelfTy(nid) => { ast::DefSelfTy(xcx.tr_id(nid)) }
-          ast::DefSelf(nid) => { ast::DefSelf(xcx.tr_id(nid)) }
+          ast::DefSelf(nid, m) => { ast::DefSelf(xcx.tr_id(nid), m) }
           ast::DefMod(did) => { ast::DefMod(did.tr(xcx)) }
           ast::DefForeignMod(did) => { ast::DefForeignMod(did.tr(xcx)) }
           ast::DefStatic(did, m) => { ast::DefStatic(did.tr(xcx), m) }

src/librustc/middle/liveness.rs

@@ -392,7 +392,7 @@ fn visit_fn(v: &mut LivenessVisitor,
     match *fk {
         visit::fk_method(_, _, method) => {
             match method.explicit_self.node {
-                sty_value | sty_region(*) | sty_box(_) | sty_uniq => {
+                sty_value(_) | sty_region(*) | sty_box(_) | sty_uniq(_) => {
                     fn_maps.add_variable(Arg(method.self_id,
                                              special_idents::self_));
                 }

src/librustc/middle/mem_categorization.rs

@@ -488,12 +488,12 @@ impl mem_categorization_ctxt {
             }
           }
 
-          ast::DefSelf(self_id) => {
+          ast::DefSelf(self_id, mutbl) => {
             @cmt_ {
                 id:id,
                 span:span,
                 cat:cat_self(self_id),
-                mutbl: McImmutable,
+                mutbl: if mutbl { McDeclared } else { McImmutable },
                 ty:expr_ty
             }
           }

src/librustc/middle/moves.rs

@@ -227,7 +227,7 @@ pub fn moved_variable_node_id_from_def(def: Def) -> Option<NodeId> {
       DefBinding(nid, _) |
       DefArg(nid, _) |
       DefLocal(nid, _) |
-      DefSelf(nid) => Some(nid),
+      DefSelf(nid, _) => Some(nid),
 
       _ => None
     }

src/librustc/middle/resolve.rs

@@ -150,7 +150,7 @@ enum Mutability {
 
 enum SelfBinding {
     NoSelfBinding,
-    HasSelfBinding(NodeId)
+    HasSelfBinding(NodeId, explicit_self)
 }
 
 impl Visitor<()> for Resolver {
@@ -3799,8 +3799,12 @@ impl Resolver {
                 NoSelfBinding => {
                     // Nothing to do.
                 }
-                HasSelfBinding(self_node_id) => {
-                    let def_like = DlDef(DefSelf(self_node_id));
+                HasSelfBinding(self_node_id, explicit_self) => {
+                    let mutable = match explicit_self.node {
+                        sty_uniq(m) | sty_value(m) if m == MutMutable => true,
+                        _ => false
+                    };
+                    let def_like = DlDef(DefSelf(self_node_id, mutable));
                     *function_value_rib.self_binding = Some(def_like);
                 }
             }
@@ -3937,7 +3941,7 @@ impl Resolver {
         // we only have self ty if it is a non static method
         let self_binding = match method.explicit_self.node {
           sty_static => { NoSelfBinding }
-          _ => { HasSelfBinding(method.self_id) }
+          _ => { HasSelfBinding(method.self_id, method.explicit_self) }
         };
 
         self.resolve_function(rib_kind,

src/librustc/middle/trans/expr.rs

@@ -1099,7 +1099,7 @@ pub fn trans_local_var(bcx: @mut Block, def: ast::Def) -> Datum {
         ast::DefLocal(nid, _) | ast::DefBinding(nid, _) => {
             take_local(bcx, bcx.fcx.lllocals, nid)
         }
-        ast::DefSelf(nid) => {
+        ast::DefSelf(nid, _) => {
             let self_info: ValSelfData = match bcx.fcx.llself {
                 Some(ref self_info) => *self_info,
                 None => {

src/librustc/middle/trans/inline.rs

@@ -144,7 +144,7 @@ pub fn maybe_instantiate_inline(ccx: @mut CrateContext, fn_id: ast::DefId)
                       debug!("calling inline trans_fn with self_ty {}",
                              ty_to_str(ccx.tcx, self_ty));
                       match mth.explicit_self.node {
-                          ast::sty_value => impl_self(self_ty, ty::ByRef),
+                          ast::sty_value(_) => impl_self(self_ty, ty::ByRef),
                           _ => impl_self(self_ty, ty::ByCopy),
                       }
                   }