auto merge of #16762 : huonw/rust/for-error-nice, r=alexcrichton

- print the type of `x` in `for ... in x` in the "does not implement Iterator" message
- avoid printing that message if `x` has a type error
This commit is contained in:
bors 2014-08-29 08:21:26 +00:00
commit f6a7ab40e8
3 changed files with 28 additions and 6 deletions

View File

@ -2168,12 +2168,13 @@ fn lookup_method_for_for_loop(fcx: &FnCtxt,
}
};
let expr_type = fcx.expr_ty(&*iterator_expr);
let method = method::lookup_in_trait(fcx,
iterator_expr.span,
Some(&*iterator_expr),
token::intern("next"),
trait_did,
fcx.expr_ty(&*iterator_expr),
expr_type,
[],
DontAutoderefReceiver,
IgnoreStaticMethods);
@ -2183,9 +2184,15 @@ fn lookup_method_for_for_loop(fcx: &FnCtxt,
let method_type = match method {
Some(ref method) => method.ty,
None => {
fcx.tcx().sess.span_err(iterator_expr.span,
"`for` loop expression does not \
implement the `Iterator` trait");
let true_expr_type = fcx.infcx().resolve_type_vars_if_possible(expr_type);
if !ty::type_is_error(true_expr_type) {
let ty_string = fcx.infcx().ty_to_string(true_expr_type);
fcx.tcx().sess.span_err(iterator_expr.span,
format!("`for` loop expression has type `{}` which does \
not implement the `Iterator` trait",
ty_string).as_slice());
}
ty::mk_err()
}
};

View File

@ -24,8 +24,7 @@ pub fn main() {
x: 1,
y: 2,
};
for x in bogus { //~ ERROR does not implement the `Iterator` trait
for x in bogus { //~ ERROR has type `MyStruct` which does not implement the `Iterator` trait
drop(x);
}
}

View File

@ -0,0 +1,16 @@
// 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.
pub fn main() {
let x = () + (); //~ ERROR binary operation
// this shouldn't have a flow-on error:
for _ in x {}
}