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Bonus fix for #35280. Part of #35233. Fixes #36057. Adding expanded notes/context for what trait a parameter shadows as part of E0194 error messages.

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This commit is contained in:
William Lee 2016-08-30 17:30:08 -04:00
parent 4473130f4e
commit 69f0cee85d
2 changed files with 24 additions and 8 deletions
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28
src/librustc_typeck/check/wfcheck.rs
View File

@ -16,7 +16,7 @@ use middle::region::{CodeExtent};
use rustc::infer::TypeOrigin;
use rustc::traits;
use rustc::ty::{self, Ty, TyCtxt};
use rustc::util::nodemap::FnvHashSet;
use rustc::util::nodemap::{FnvHashSet, FnvHashMap};
use syntax::ast;
use syntax_pos::Span;
@ -519,11 +519,26 @@ impl<'ccx, 'gcx> CheckTypeWellFormedVisitor<'ccx, 'gcx> {
fn reject_shadowing_type_parameters(tcx: TyCtxt, span: Span, generics: &ty::Generics) {
let parent = tcx.lookup_generics(generics.parent.unwrap());
let impl_params: FnvHashSet<_> = parent.types.iter().map(|tp| tp.name).collect();
let impl_params: FnvHashMap<_, _> = parent.types
.iter()
.map(|tp| (tp.name, tp.def_id))
.collect();
for method_param in &generics.types {
if impl_params.contains(&method_param.name) {
error_194(tcx, span, method_param.name);
if impl_params.contains_key(&method_param.name) {
// Tighten up the span to focus on only the shadowing type
let shadow_node_id = tcx.map.as_local_node_id(method_param.def_id).unwrap();
let type_span = match tcx.map.opt_span(shadow_node_id) {
Some(osp) => osp,
None => span
};
// The expectation here is that the original trait declaration is
// local so it should be okay to just unwrap everything.
let trait_def_id = impl_params.get(&method_param.name).unwrap();
let trait_node_id = tcx.map.as_local_node_id(*trait_def_id).unwrap();
let trait_decl_span = tcx.map.opt_span(trait_node_id).unwrap();
error_194(tcx, type_span, trait_decl_span, method_param.name);
}
}
}
@ -630,10 +645,11 @@ fn error_392<'a, 'tcx>(ccx: &CrateCtxt<'a, 'tcx>, span: Span, param_name: ast::N
err
}
fn error_194(tcx: TyCtxt, span: Span, name: ast::Name) {
fn error_194(tcx: TyCtxt, span: Span, trait_decl_span: Span, name: ast::Name) {
struct_span_err!(tcx.sess, span, E0194,
"type parameter `{}` shadows another type parameter of the same name",
name)
.span_label(span, &format!("`{}` shadows another type parameter", name))
.span_label(span, &format!("shadows another type parameter"))
.span_label(trait_decl_span, &format!("first `{}` declared here", name))
.emit();
}

4
src/test/compile-fail/E0194.rs
View File

@ -8,11 +8,11 @@
// option. This file may not be copied, modified, or distributed
// except according to those terms.
trait Foo<T> {
trait Foo<T> { //~ NOTE first `T` declared here
fn do_something(&self) -> T;
fn do_something_else<T: Clone>(&self, bar: T);
//~^ ERROR E0194
//~| NOTE `T` shadows another type parameter
//~| NOTE shadows another type parameter
}
fn main() {