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Make the error messages that result from referencing

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nonexistent traits consistent, and add a test.
This commit is contained in:
Gareth Smith 2013-07-03 22:16:08 +01:00
parent 0c6fc46c03
commit 656c8f9143
2 changed files with 43 additions and 23 deletions
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46
src/librustc/middle/resolve.rs
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@ -510,6 +510,13 @@ pub struct NameBindings {
value_def: Option<ValueNsDef>, //< Meaning in value namespace.
}
/// Ways in which a trait can be referenced
enum TraitReferenceType {
TraitImplementation, // impl SomeTrait for T { ... }
TraitDerivation, // trait T : SomeTrait { ... }
TraitBoundingTypeParameter, // fn f<T:SomeTrait>() { ... }
}
impl NameBindings {
/// Creates a new module in this set of name bindings.
pub fn define_module(@mut self,
@ -3554,23 +3561,7 @@ pub fn resolve_item(@mut self, item: @item, visitor: ResolveVisitor) {
// Resolve derived traits.
for traits.iter().advance |trt| {
match self.resolve_path(trt.path, TypeNS, true,
visitor) {
None =>
self.session.span_err(trt.path.span,
"attempt to derive a \
nonexistent trait"),
Some(def) => {
// Write a mapping from the trait ID to the
// definition of the trait into the definition
// map.
debug!("(resolving trait) found trait def: \
%?", def);
self.record_def(trt.ref_id, def);
}
}
self.resolve_trait_reference(*trt, visitor, TraitDerivation);
}
for (*methods).iter().advance |method| {
@ -3821,7 +3812,7 @@ pub fn resolve_type_parameter_bound(@mut self,
visitor: ResolveVisitor) {
match *type_parameter_bound {
TraitTyParamBound(tref) => {
self.resolve_trait_reference(tref, visitor)
self.resolve_trait_reference(tref, visitor, TraitBoundingTypeParameter)
}
RegionTyParamBound => {}
}
@ -3829,14 +3820,23 @@ pub fn resolve_type_parameter_bound(@mut self,
pub fn resolve_trait_reference(@mut self,
trait_reference: &trait_ref,
visitor: ResolveVisitor) {
visitor: ResolveVisitor,
reference_type: TraitReferenceType) {
match self.resolve_path(trait_reference.path, TypeNS, true, visitor) {
None => {
let idents = self.idents_to_str(trait_reference.path.idents);
self.session.span_err(trait_reference.path.span,
fmt!("attempt to implement an unknown trait `%s`", idents));
let path_str = self.idents_to_str(trait_reference.path.idents);
let usage_str = match reference_type {
TraitBoundingTypeParameter => "bound type parameter to",
TraitImplementation => "implement",
TraitDerivation => "derive"
};
let msg = fmt!("attempt to %s a nonexistent trait `%s`", usage_str, path_str);
self.session.span_err(trait_reference.path.span, msg);
}
Some(def) => {
debug!("(resolving trait) found trait def: %?", def);
self.record_def(trait_reference.ref_id, def);
}
}
@ -3930,7 +3930,7 @@ pub fn resolve_implementation(@mut self,
let original_trait_refs;
match opt_trait_reference {
Some(trait_reference) => {
self.resolve_trait_reference(trait_reference, visitor);
self.resolve_trait_reference(trait_reference, visitor, TraitImplementation);
// Record the current set of trait references.
let mut new_trait_refs = ~[];

20
src/test/compile-fail/resolve-unknown-trait.rs Normal file
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@ -0,0 +1,20 @@
// Copyright 2013 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.
trait NewTrait : SomeNonExistentTrait {}
//~^ ERROR attempt to derive a nonexistent trait `SomeNonExistentTrait`
impl SomeNonExistentTrait for int {}
//~^ ERROR attempt to implement a nonexistent trait `SomeNonExistentTrait`
fn f<T:SomeNonExistentTrait>() {}
//~^ ERROR attempt to bound type parameter to a nonexistent trait `SomeNonExistentTrait`