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Special-case some error messages about Sized

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The error messages still aren’t as good as they were before DST, but they better
describe the actual problem, not mentioning `Sized` at all (because that bound
is normally implied, not explicitly stated).

Closes #17567.
Closes #18040.
Closes #18159.
This commit is contained in:
P1start 2014-10-28 21:04:08 +13:00
parent 14398f2929
commit 737e39696b
4 changed files with 34 additions and 12 deletions
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28
src/librustc/middle/typeck/check/vtable.rs
View File

@ -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.

3
src/test/compile-fail/issue-16562.rs
View File

@ -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!()
}

2
src/test/compile-fail/issue-17551.rs
View File

@ -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;
}

13
src/test/compile-fail/issue-18159.rs Normal file
View File

@ -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
}