syntax: make deriving have slightly less cryptic error messages.

This unfortunately changes an error like

    error: mismatched types: expected `&&NotClone` but found `&NotClone`

into

    error: type `NotClone` does not implement any method in scope named `clone`

Author: huonw

src/etc/generate-deriving-span-tests.py

@@ -118,7 +118,7 @@ def write_file(name, string):
 for (trait, supers, errs) in [('Rand', [], 1),
                               ('Clone', [], 1), ('DeepClone', ['Clone'], 1),
                               ('Eq', [], 2), ('Ord', [], 8),
-                              ('TotalEq', [], 2), ('TotalOrd', ['TotalEq'], 2)]:
+                              ('TotalEq', [], 1), ('TotalOrd', ['TotalEq'], 1)]:
     traits[trait] = (ALL, supers, errs)
 
 for (trait, (types, super_traits, error_count)) in traits.items():

src/libextra/dlist.rs

@@ -47,13 +47,17 @@ struct Node<T> {
 }
 
 /// Double-ended DList iterator
-#[deriving(Clone)]
 pub struct Items<'a, T> {
     priv head: &'a Link<T>,
     priv tail: Rawlink<Node<T>>,
     priv nelem: uint,
 }
 
+// FIXME #11820: the &'a Option<> of the Link stops clone working.
+impl<'a, T> Clone for Items<'a, T> {
+    fn clone(&self) -> Items<'a, T> { *self }
+}
+
 /// Double-ended mutable DList iterator
 pub struct MutItems<'a, T> {
     priv list: &'a mut DList<T>,

src/librustc/middle/trans/_match.rs

@@ -399,13 +399,17 @@ struct BindingInfo {
 
 type BindingsMap = HashMap<Ident, BindingInfo>;
 
-#[deriving(Clone)]
 struct ArmData<'a,'b> {
     bodycx: &'b Block<'b>,
     arm: &'a ast::Arm,
     bindings_map: @BindingsMap
 }
 
+// FIXME #11820: method resolution is unreliable with &
+impl<'a,'b> Clone for ArmData<'a, 'b> {
+    fn clone(&self) -> ArmData<'a, 'b> { *self }
+}
+
 /**
  * Info about Match.
  * If all `pats` are matched then arm `data` will be executed.
@@ -2227,5 +2231,3 @@ fn bind_irrefutable_pat<'a>(
     }
     return bcx;
 }
-
-

src/libsyntax/ext/deriving/cmp/ord.rs

@@ -78,14 +78,10 @@ fn cs_op(less: bool, equal: bool, cx: &ExtCtxt, span: Span, substr: &Substructur
                 _ => cx.span_bug(span, "Not exactly 2 arguments in `deriving(Ord)`")
             };
 
-            let cmp = cx.expr_binary(span, op,
-                                     cx.expr_deref(span, self_f),
-                                     cx.expr_deref(span, other_f));
+            let cmp = cx.expr_binary(span, op, self_f, other_f);
 
             let not_cmp = cx.expr_unary(span, ast::UnNot,
-                                        cx.expr_binary(span, op,
-                                                       cx.expr_deref(span, other_f),
-                                                       cx.expr_deref(span, self_f)));
+                                        cx.expr_binary(span, op, other_f, self_f));
 
             let and = cx.expr_binary(span, ast::BiAnd, not_cmp, subexpr);
             cx.expr_binary(span, ast::BiOr, cmp, and)

src/libsyntax/ext/deriving/generic.rs

@@ -1009,7 +1009,8 @@ impl<'a> TraitDef<'a> {
             };
             let path = cx.path_ident(sp, cx.ident_of(format!("{}_{}", prefix, i)));
             paths.push(path.clone());
-            ident_expr.push((sp, opt_id, cx.expr_path(path)));
+            let val = cx.expr(sp, ast::ExprParen(cx.expr_deref(sp, cx.expr_path(path))));
+            ident_expr.push((sp, opt_id, val));
         }
 
         let subpats = self.create_subpatterns(paths, mutbl);
@@ -1053,7 +1054,8 @@ impl<'a> TraitDef<'a> {
                     let path = cx.path_ident(sp, cx.ident_of(format!("{}_{}", prefix, i)));
 
                     paths.push(path.clone());
-                    ident_expr.push((sp, None, cx.expr_path(path)));
+                    let val = cx.expr(sp, ast::ExprParen(cx.expr_deref(sp, cx.expr_path(path))));
+                    ident_expr.push((sp, None, val));
                 }
 
                 let subpats = self.create_subpatterns(paths, mutbl);
@@ -1128,7 +1130,7 @@ pub fn cs_same_method(f: |&ExtCtxt, Span, ~[@Expr]| -> @Expr,
                 cx.expr_method_call(field.span,
                                     field.self_,
                                     substructure.method_ident,
-                                    field.other.clone())
+                                    field.other.map(|e| cx.expr_addr_of(field.span, *e)))
             });
 
             f(cx, trait_span, called)

src/test/compile-fail/deriving-no-inner-impl-error-message.rs

@@ -0,0 +1,24 @@
+// Copyright 2014 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.
+
+struct NoCloneOrEq;
+
+#[deriving(Eq)]
+struct E {
+    x: NoCloneOrEq //~ ERROR does not implement any method in scope named `eq`
+         //~^ ERROR does not implement any method in scope named `ne`
+}
+#[deriving(Clone)]
+struct C {
+    x: NoCloneOrEq //~ ERROR does not implement any method in scope named `clone`
+}
+
+
+fn main() {}

src/test/compile-fail/deriving-span-TotalEq-enum-struct-variant.rs

@@ -20,7 +20,6 @@ struct Error;
 enum Enum {
    A {
      x: Error //~ ERROR
-//~^ ERROR
    }
 }
 

src/test/compile-fail/deriving-span-TotalEq-enum.rs

@@ -20,7 +20,6 @@ struct Error;
 enum Enum {
    A(
      Error //~ ERROR
-//~^ ERROR
      )
 }
 

src/test/compile-fail/deriving-span-TotalEq-struct.rs

@@ -19,7 +19,6 @@ struct Error;
 #[deriving(TotalEq)]
 struct Struct {
     x: Error //~ ERROR
-//~^ ERROR
 }
 
 fn main() {}

src/test/compile-fail/deriving-span-TotalEq-tuple-struct.rs

@@ -19,7 +19,6 @@ struct Error;
 #[deriving(TotalEq)]
 struct Struct(
     Error //~ ERROR
-//~^ ERROR
 );
 
 fn main() {}