Some fixes to diagnostics and lints

src/librustc/driver/mod.rs

@@ -255,7 +255,8 @@ Available lint options:
         for (name, to) in lints.into_iter() {
             let name = name.chars().map(|x| x.to_lowercase())
                            .collect::<String>().replace("_", "-");
-            let desc = to.into_iter().map(|x| x.as_str()).collect::<Vec<String>>().connect(", ");
+            let desc = to.into_iter().map(|x| x.as_str().replace("_", "-"))
+                         .collect::<Vec<String>>().connect(", ");
             println!("    {}  {}",
                      padded(name.as_slice()), desc);
         }

src/librustc/lint/context.rs

@@ -221,8 +221,8 @@ impl LintStore {
 
         add_lint_group!(sess, "unused",
                         UNUSED_IMPORTS, UNUSED_VARIABLES, UNUSED_ASSIGNMENTS, DEAD_CODE,
-                        UNUSED_MUT, UNREACHABLE_CODE, UNUSED_EXTERN_CRATES, UNUSED_MUST_USE,
-                        UNUSED_UNSAFE, UNUSED_RESULTS, PATH_STATEMENTS)
+                        UNUSED_MUT, UNREACHABLE_CODE, UNUSED_MUST_USE,
+                        UNUSED_UNSAFE, PATH_STATEMENTS)
 
         // We have one lint pass defined in this module.
         self.register_pass(sess, false, box GatherNodeLevels as LintPassObject);

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

@@ -303,15 +303,25 @@ pub fn maybe_report_ambiguity(fcx: &FnCtxt, obligation: &Obligation) {
         // has_errors() to be sure that compilation isn't happening
         // anyway. In that case, why inundate the user.
         if !fcx.tcx().sess.has_errors() {
-            fcx.tcx().sess.span_err(
-                obligation.cause.span,
-                format!(
-                    "unable to infer enough type information to \
-                     locate the impl of the trait `{}` for \
-                     the type `{}`; type annotations required",
-                    trait_ref.user_string(fcx.tcx()),
-                    self_ty.user_string(fcx.tcx())).as_slice());
-            note_obligation_cause(fcx, obligation);
+            if fcx.ccx.tcx.lang_items.sized_trait()
+                  .map_or(false, |sized_id| sized_id == trait_ref.def_id) {
+                fcx.tcx().sess.span_err(
+                    obligation.cause.span,
+                    format!(
+                        "unable to infer enough type information about `{}`; type annotations \
+                         required",
+                        self_ty.user_string(fcx.tcx())).as_slice());
+            } else {
+                fcx.tcx().sess.span_err(
+                    obligation.cause.span,
+                    format!(
+                        "unable to infer enough type information to \
+                         locate the impl of the trait `{}` for \
+                         the type `{}`; type annotations required",
+                        trait_ref.user_string(fcx.tcx()),
+                        self_ty.user_string(fcx.tcx())).as_slice());
+                note_obligation_cause(fcx, obligation);
+            }
         }
     } else if !fcx.tcx().sess.has_errors() {
          // Ambiguity. Coherence should have reported an error.

src/libsyntax/parse/parser.rs

@@ -2730,6 +2730,8 @@ impl<'a> Parser<'a> {
                 return self.parse_dot_or_call_expr();
             }
 
+            let lo = self.span.lo;
+
             self.bump();
 
             // Check for a place: `box(PLACE) EXPR`.
@@ -2738,6 +2740,18 @@ impl<'a> Parser<'a> {
                 if !self.eat(&token::RParen) {
                     let place = self.parse_expr();
                     self.expect(&token::RParen);
+                    // Give a suggestion to use `box()` when a parenthesised expression is used
+                    if !self.token.can_begin_expr() {
+                        let span = self.span;
+                        let this_token_to_string = self.this_token_to_string();
+                        self.span_err(span,
+                                      format!("expected expression, found `{}`",
+                                              this_token_to_string).as_slice());
+                        let box_span = mk_sp(lo, self.last_span.hi);
+                        self.span_help(box_span,
+                                       "perhaps you meant `box() (foo)` instead?");
+                        self.abort_if_errors();
+                    }
                     let subexpression = self.parse_prefix_expr();
                     hi = subexpression.span.hi;
                     ex = ExprBox(place, subexpression);
@@ -3578,6 +3592,16 @@ impl<'a> Parser<'a> {
             let hi = self.span.hi;
 
             if id.name == token::special_idents::invalid.name {
+                if self.token == token::Dot {
+                    let span = self.span;
+                    let token_string = self.this_token_to_string();
+                    self.span_err(span,
+                                  format!("expected statement, found `{}`",
+                                          token_string).as_slice());
+                    let mac_span = mk_sp(lo, hi);
+                    self.span_help(mac_span, "try parenthesizing this macro invocation");
+                    self.abort_if_errors();
+                }
                 P(spanned(lo, hi, StmtMac(
                     spanned(lo, hi, MacInvocTT(pth, tts, EMPTY_CTXT)), false)))
             } else {

src/test/compile-fail/issue-16562.rs

@@ -16,8 +16,7 @@ struct Col<D, C> {
 }
 
 impl<T, M: MatrixShape> Collection for Col<M, uint> {
-//~^ ERROR unable to infer enough type information to locate the impl of the trait
-//~^^ NOTE the trait `core::kinds::Sized` must be implemented because it is required by
+//~^ ERROR unable to infer enough type information
     fn len(&self) -> uint {
         unimplemented!()
     }

src/test/compile-fail/issue-17551.rs

@@ -13,6 +13,6 @@
 struct B<T>;
 
 fn main() {
-    let foo = B; //~ ERROR unable to infer enough type information to locate the impl of the trait
+    let foo = B; //~ ERROR unable to infer enough type information
     let closure = |:| foo;
 }

src/test/compile-fail/issue-18159.rs

@@ -0,0 +1,13 @@
+// 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.
+
+fn main() {
+    let x; //~ ERROR unable to infer enough type information
+}

src/test/compile-fail/macro-invocation-dot-help.rs

@@ -0,0 +1,14 @@
+// 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.
+
+fn main() {
+    foo!() //~ HELP try parenthesizing this macro invocation
+    .bar //~ ERROR expected statement
+}

src/test/compile-fail/parenthesized-box-expr-message.rs

@@ -0,0 +1,14 @@
+// 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.
+
+fn main() {
+    box(1 + 1) //~ HELP perhaps you meant `box() (foo)` instead?
+    ; //~ ERROR expected expression, found `;`
+}