auto merge of #7262 : nikomatsakis/rust/ref-bindings-in-irrefut-patterns, r=catamorphism

Correct treatment of irrefutable patterns. The old code was wrong in many, many ways. `ref` bindings didn't work, it sometimes copied when it should have moved, the borrow checker didn't even look at such patterns at all, we weren't consistent about preventing values with destructors from being pulled apart, etc.

Fixes #3224.
Fixes #3225.
Fixes #3255.
Fixes #6225.
Fixes #6386.

r? @catamorphism

3 files changed, 25 insertions, 17 deletions

diff --git a/src/libsyntax/ext/deriving/generic.rs b/src/libsyntax/ext/deriving/generic.rs
index 01769482d08..3bc16477c80 100644
--- a/src/libsyntax/ext/deriving/generic.rs
+++ b/src/libsyntax/ext/deriving/generic.rs
@@ -519,8 +519,8 @@ impl<'self> MethodDef<'self> {
         // create the generics that aren't for Self
         let fn_generics = self.generics.to_generics(cx, span, type_ident, generics);
 
-        let args = do arg_types.map |&(id, ty)| {
-            cx.arg(span, id, ty)
+        let args = do arg_types.map |pair| {
+            cx.arg(span, pair.first(), pair.second())
         };
 
         let ret_type = self.get_ret_ty(cx, span, generics, type_ident);
@@ -589,7 +589,7 @@ impl<'self> MethodDef<'self> {
 
         // transpose raw_fields
         let fields = match raw_fields {
-            [self_arg, .. rest] => {
+            [ref self_arg, .. rest] => {
                 do self_arg.iter().enumerate().transform |(i, &(opt_id, field))| {
                     let other_fields = do rest.map |l| {
                         match &l[i] {
@@ -738,16 +738,20 @@ impl<'self> MethodDef<'self> {
 
                     let mut enum_matching_fields = vec::from_elem(self_vec.len(), ~[]);
 
-                    for matches_so_far.tail().iter().advance |&(_, _, other_fields)| {
-                        for other_fields.iter().enumerate().advance |(i, &(_, other_field))| {
-                            enum_matching_fields[i].push(other_field);
+                    for matches_so_far.tail().iter().advance |triple| {
+                        match triple {
+                            &(_, _, ref other_fields) => {
+                                for other_fields.iter().enumerate().advance |(i, pair)| {
+                                    enum_matching_fields[i].push(pair.second());
+                                }
+                            }
                         }
                     }
                     let field_tuples =
                         do self_vec.iter()
                            .zip(enum_matching_fields.iter())
-                           .transform |(&(id, self_f), &other)| {
-                        (id, self_f, other)
+                           .transform |(&(id, self_f), other)| {
+                        (id, self_f, copy *other)
                     }.collect();
                     substructure = EnumMatching(variant_index, variant, field_tuples);
                 }
@@ -892,8 +896,8 @@ pub fn create_subpatterns(cx: @ExtCtxt,
                           field_paths: ~[ast::Path],
                           mutbl: ast::mutability)
                    -> ~[@ast::pat] {
-    do field_paths.map |&path| {
-        cx.pat(span, ast::pat_ident(ast::bind_by_ref(mutbl), path, None))
+    do field_paths.map |path| {
+        cx.pat(span, ast::pat_ident(ast::bind_by_ref(mutbl), copy *path, None))
     }
 }
 
@@ -1015,7 +1019,8 @@ left-to-right (`true`) or right-to-left (`false`).
 pub fn cs_fold(use_foldl: bool,
                f: &fn(@ExtCtxt, span,
                       old: @expr,
-                      self_f: @expr, other_fs: &[@expr]) -> @expr,
+                      self_f: @expr,
+                      other_fs: &[@expr]) -> @expr,
                base: @expr,
                enum_nonmatch_f: EnumNonMatchFunc,
                cx: @ExtCtxt, span: span,
@@ -1023,11 +1028,13 @@ pub fn cs_fold(use_foldl: bool,
     match *substructure.fields {
         EnumMatching(_, _, ref all_fields) | Struct(ref all_fields) => {
             if use_foldl {
-                do all_fields.iter().fold(base) |old, &(_, self_f, other_fs)| {
+                do all_fields.iter().fold(base) |old, triple| {
+                    let (_, self_f, other_fs) = copy *triple;
                     f(cx, span, old, self_f, other_fs)
                 }
             } else {
-                do all_fields.rev_iter().fold(base) |old, &(_, self_f, other_fs)| {
+                do all_fields.rev_iter().fold(base) |old, triple| {
+                    let (_, self_f, other_fs) = copy *triple;
                     f(cx, span, old, self_f, other_fs)
                 }
             }
@@ -1059,7 +1066,8 @@ pub fn cs_same_method(f: &fn(@ExtCtxt, span, ~[@expr]) -> @expr,
     match *substructure.fields {
         EnumMatching(_, _, ref all_fields) | Struct(ref all_fields) => {
             // call self_n.method(other_1_n, other_2_n, ...)
-            let called = do all_fields.map |&(_, self_field, other_fields)| {
+            let called = do all_fields.map |triple| {
+                let (_, self_field, other_fields) = copy *triple;
                 cx.expr_method_call(span,
                                     self_field,
                                     substructure.method_ident,
diff --git a/src/libsyntax/ext/pipes/pipec.rs b/src/libsyntax/ext/pipes/pipec.rs
index 98fc9aa6178..478c0861990 100644
--- a/src/libsyntax/ext/pipes/pipec.rs
+++ b/src/libsyntax/ext/pipes/pipec.rs
@@ -137,7 +137,7 @@ impl gen_send for message {
                 let arg_names = vec::from_fn(tys.len(), |i| "x_" + i.to_str());
 
                 let args_ast: ~[ast::arg] = arg_names.iter().zip(tys.iter())
-                    .transform(|(&n, t)| cx.arg(span, cx.ident_of(n), copy *t)).collect();
+                    .transform(|(n, t)| cx.arg(span, cx.ident_of(*n), copy *t)).collect();
 
                 let args_ast = vec::append(
                     ~[cx.arg(span,
diff --git a/src/libsyntax/ext/pipes/proto.rs b/src/libsyntax/ext/pipes/proto.rs
index 2fe8456c274..75424b60390 100644
--- a/src/libsyntax/ext/pipes/proto.rs
+++ b/src/libsyntax/ext/pipes/proto.rs
@@ -215,8 +215,8 @@ pub fn visit<Tproto, Tstate, Tmessage, V: visitor<Tproto, Tstate, Tmessage>>(
 
     // the copy keywords prevent recursive use of dvec
     let states: ~[Tstate] = do (copy proto.states).iter().transform |&s| {
-        let messages: ~[Tmessage] = do (copy s.messages).iter().transform |&m| {
-            let message(name, span, tys, this, next) = m;
+        let messages: ~[Tmessage] = do (copy s.messages).iter().transform |m| {
+            let message(name, span, tys, this, next) = copy *m;
             visitor.visit_message(name, span, tys, this, next)
         }.collect();
         visitor.visit_state(s, messages)