daaa9a440c
Commit 7ed00caacc improved our error reporting by including the target
function in our error messages when there is an argument count mismatch.
A simple example from the UI tests is:
```
error[E0593]: function is expected to take a single 2-tuple as argument, but it takes 0 arguments
--> $DIR/closure-arg-count.rs:32:53
|
32 | let _it = vec![1, 2, 3].into_iter().enumerate().map(foo);
| ^^^ expected function that takes a single 2-tuple as argument
...
44 | fn foo() {}
| -------- takes 0 arguments
```
However, this assumed the target span was always available. This does
not hold true if the target function is in `std` or another crate. A
simple example from #48046 is assigning `str::split` to a function type
with a different number of arguments.
Fix by removing all of the labels and suggestions related to the target
span when it's not found.
Fixes #48046
1355 lines
59 KiB
Rust
1355 lines
59 KiB
Rust
// Copyright 2014 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use super::{
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FulfillmentError,
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FulfillmentErrorCode,
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MismatchedProjectionTypes,
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Obligation,
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ObligationCause,
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ObligationCauseCode,
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OnUnimplementedDirective,
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OnUnimplementedNote,
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OutputTypeParameterMismatch,
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TraitNotObjectSafe,
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ConstEvalFailure,
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PredicateObligation,
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Reveal,
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SelectionContext,
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SelectionError,
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ObjectSafetyViolation,
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};
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use errors::DiagnosticBuilder;
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use hir;
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use hir::def_id::DefId;
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use infer::{self, InferCtxt};
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use infer::type_variable::TypeVariableOrigin;
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use middle::const_val;
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use std::fmt;
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use syntax::ast;
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use session::DiagnosticMessageId;
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use ty::{self, AdtKind, ToPredicate, ToPolyTraitRef, Ty, TyCtxt, TypeFoldable};
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use ty::error::ExpectedFound;
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use ty::fast_reject;
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use ty::fold::TypeFolder;
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use ty::subst::Subst;
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use ty::SubtypePredicate;
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use util::nodemap::{FxHashMap, FxHashSet};
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use syntax_pos::{DUMMY_SP, Span};
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impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
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pub fn report_fulfillment_errors(&self,
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errors: &Vec<FulfillmentError<'tcx>>,
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body_id: Option<hir::BodyId>) {
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#[derive(Debug)]
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struct ErrorDescriptor<'tcx> {
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predicate: ty::Predicate<'tcx>,
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index: Option<usize>, // None if this is an old error
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}
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let mut error_map : FxHashMap<_, _> =
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self.reported_trait_errors.borrow().iter().map(|(&span, predicates)| {
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(span, predicates.iter().map(|predicate| ErrorDescriptor {
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predicate: predicate.clone(),
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index: None
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}).collect())
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}).collect();
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for (index, error) in errors.iter().enumerate() {
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error_map.entry(error.obligation.cause.span).or_insert(Vec::new()).push(
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ErrorDescriptor {
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predicate: error.obligation.predicate.clone(),
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index: Some(index)
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});
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self.reported_trait_errors.borrow_mut()
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.entry(error.obligation.cause.span).or_insert(Vec::new())
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.push(error.obligation.predicate.clone());
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}
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// We do this in 2 passes because we want to display errors in order, tho
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// maybe it *is* better to sort errors by span or something.
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let mut is_suppressed: Vec<bool> = errors.iter().map(|_| false).collect();
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for (_, error_set) in error_map.iter() {
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// We want to suppress "duplicate" errors with the same span.
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for error in error_set {
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if let Some(index) = error.index {
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// Suppress errors that are either:
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// 1) strictly implied by another error.
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// 2) implied by an error with a smaller index.
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for error2 in error_set {
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if error2.index.map_or(false, |index2| is_suppressed[index2]) {
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// Avoid errors being suppressed by already-suppressed
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// errors, to prevent all errors from being suppressed
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// at once.
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continue
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}
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if self.error_implies(&error2.predicate, &error.predicate) &&
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!(error2.index >= error.index &&
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self.error_implies(&error.predicate, &error2.predicate))
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{
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info!("skipping {:?} (implied by {:?})", error, error2);
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is_suppressed[index] = true;
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break
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}
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}
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}
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}
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}
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for (error, suppressed) in errors.iter().zip(is_suppressed) {
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if !suppressed {
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self.report_fulfillment_error(error, body_id);
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}
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}
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}
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// returns if `cond` not occurring implies that `error` does not occur - i.e. that
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// `error` occurring implies that `cond` occurs.
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fn error_implies(&self,
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cond: &ty::Predicate<'tcx>,
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error: &ty::Predicate<'tcx>)
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-> bool
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{
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if cond == error {
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return true
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}
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let (cond, error) = match (cond, error) {
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(&ty::Predicate::Trait(..), &ty::Predicate::Trait(ref error))
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=> (cond, error),
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_ => {
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// FIXME: make this work in other cases too.
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return false
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}
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};
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for implication in super::elaborate_predicates(self.tcx, vec![cond.clone()]) {
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if let ty::Predicate::Trait(implication) = implication {
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let error = error.to_poly_trait_ref();
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let implication = implication.to_poly_trait_ref();
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// FIXME: I'm just not taking associated types at all here.
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// Eventually I'll need to implement param-env-aware
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// `Γ₁ ⊦ φ₁ => Γ₂ ⊦ φ₂` logic.
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let param_env = ty::ParamEnv::empty(Reveal::UserFacing);
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if let Ok(_) = self.can_sub(param_env, error, implication) {
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debug!("error_implies: {:?} -> {:?} -> {:?}", cond, error, implication);
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return true
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}
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}
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}
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false
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}
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fn report_fulfillment_error(&self, error: &FulfillmentError<'tcx>,
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body_id: Option<hir::BodyId>) {
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debug!("report_fulfillment_errors({:?})", error);
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match error.code {
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FulfillmentErrorCode::CodeSelectionError(ref e) => {
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self.report_selection_error(&error.obligation, e);
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}
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FulfillmentErrorCode::CodeProjectionError(ref e) => {
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self.report_projection_error(&error.obligation, e);
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}
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FulfillmentErrorCode::CodeAmbiguity => {
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self.maybe_report_ambiguity(&error.obligation, body_id);
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}
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FulfillmentErrorCode::CodeSubtypeError(ref expected_found, ref err) => {
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self.report_mismatched_types(&error.obligation.cause,
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expected_found.expected,
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expected_found.found,
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err.clone())
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.emit();
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}
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}
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}
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fn report_projection_error(&self,
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obligation: &PredicateObligation<'tcx>,
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error: &MismatchedProjectionTypes<'tcx>)
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{
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let predicate =
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self.resolve_type_vars_if_possible(&obligation.predicate);
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if predicate.references_error() {
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return
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}
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self.probe(|_| {
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let err_buf;
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let mut err = &error.err;
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let mut values = None;
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// try to find the mismatched types to report the error with.
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//
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// this can fail if the problem was higher-ranked, in which
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// cause I have no idea for a good error message.
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if let ty::Predicate::Projection(ref data) = predicate {
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let mut selcx = SelectionContext::new(self);
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let (data, _) = self.replace_late_bound_regions_with_fresh_var(
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obligation.cause.span,
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infer::LateBoundRegionConversionTime::HigherRankedType,
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data);
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let normalized = super::normalize_projection_type(
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&mut selcx,
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obligation.param_env,
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data.projection_ty,
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obligation.cause.clone(),
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0
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);
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if let Err(error) = self.at(&obligation.cause, obligation.param_env)
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.eq(normalized.value, data.ty) {
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values = Some(infer::ValuePairs::Types(ExpectedFound {
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expected: normalized.value,
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found: data.ty,
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}));
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err_buf = error;
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err = &err_buf;
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}
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}
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let msg = format!("type mismatch resolving `{}`", predicate);
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let error_id = (DiagnosticMessageId::ErrorId(271),
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Some(obligation.cause.span), msg.clone());
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let fresh = self.tcx.sess.one_time_diagnostics.borrow_mut().insert(error_id);
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if fresh {
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let mut diag = struct_span_err!(
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self.tcx.sess, obligation.cause.span, E0271,
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"type mismatch resolving `{}`", predicate
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);
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self.note_type_err(&mut diag, &obligation.cause, None, values, err);
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self.note_obligation_cause(&mut diag, obligation);
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diag.emit();
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}
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});
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}
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fn fuzzy_match_tys(&self, a: Ty<'tcx>, b: Ty<'tcx>) -> bool {
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/// returns the fuzzy category of a given type, or None
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/// if the type can be equated to any type.
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fn type_category<'tcx>(t: Ty<'tcx>) -> Option<u32> {
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match t.sty {
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ty::TyBool => Some(0),
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ty::TyChar => Some(1),
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ty::TyStr => Some(2),
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ty::TyInt(..) | ty::TyUint(..) | ty::TyInfer(ty::IntVar(..)) => Some(3),
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ty::TyFloat(..) | ty::TyInfer(ty::FloatVar(..)) => Some(4),
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ty::TyRef(..) | ty::TyRawPtr(..) => Some(5),
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ty::TyArray(..) | ty::TySlice(..) => Some(6),
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ty::TyFnDef(..) | ty::TyFnPtr(..) => Some(7),
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ty::TyDynamic(..) => Some(8),
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ty::TyClosure(..) => Some(9),
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ty::TyTuple(..) => Some(10),
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ty::TyProjection(..) => Some(11),
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ty::TyParam(..) => Some(12),
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ty::TyAnon(..) => Some(13),
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ty::TyNever => Some(14),
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ty::TyAdt(adt, ..) => match adt.adt_kind() {
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AdtKind::Struct => Some(15),
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AdtKind::Union => Some(16),
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AdtKind::Enum => Some(17),
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},
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ty::TyGenerator(..) => Some(18),
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ty::TyForeign(..) => Some(19),
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ty::TyGeneratorWitness(..) => Some(20),
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ty::TyInfer(..) | ty::TyError => None
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}
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}
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match (type_category(a), type_category(b)) {
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(Some(cat_a), Some(cat_b)) => match (&a.sty, &b.sty) {
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(&ty::TyAdt(def_a, _), &ty::TyAdt(def_b, _)) => def_a == def_b,
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_ => cat_a == cat_b
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},
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// infer and error can be equated to all types
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_ => true
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}
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}
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fn impl_similar_to(&self,
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trait_ref: ty::PolyTraitRef<'tcx>,
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obligation: &PredicateObligation<'tcx>)
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-> Option<DefId>
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{
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let tcx = self.tcx;
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let param_env = obligation.param_env;
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let trait_ref = tcx.erase_late_bound_regions(&trait_ref);
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let trait_self_ty = trait_ref.self_ty();
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let mut self_match_impls = vec![];
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let mut fuzzy_match_impls = vec![];
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self.tcx.for_each_relevant_impl(
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trait_ref.def_id, trait_self_ty, |def_id| {
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let impl_substs = self.fresh_substs_for_item(obligation.cause.span, def_id);
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let impl_trait_ref = tcx
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.impl_trait_ref(def_id)
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.unwrap()
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.subst(tcx, impl_substs);
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let impl_self_ty = impl_trait_ref.self_ty();
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if let Ok(..) = self.can_eq(param_env, trait_self_ty, impl_self_ty) {
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self_match_impls.push(def_id);
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if trait_ref.substs.types().skip(1)
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.zip(impl_trait_ref.substs.types().skip(1))
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.all(|(u,v)| self.fuzzy_match_tys(u, v))
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{
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fuzzy_match_impls.push(def_id);
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}
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}
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});
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let impl_def_id = if self_match_impls.len() == 1 {
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self_match_impls[0]
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} else if fuzzy_match_impls.len() == 1 {
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fuzzy_match_impls[0]
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} else {
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return None
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};
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if tcx.has_attr(impl_def_id, "rustc_on_unimplemented") {
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Some(impl_def_id)
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} else {
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None
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}
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}
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fn on_unimplemented_note(
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&self,
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trait_ref: ty::PolyTraitRef<'tcx>,
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obligation: &PredicateObligation<'tcx>) ->
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OnUnimplementedNote
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{
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let def_id = self.impl_similar_to(trait_ref, obligation)
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.unwrap_or(trait_ref.def_id());
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let trait_ref = *trait_ref.skip_binder();
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let desugaring;
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let method;
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let mut flags = vec![];
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let direct = match obligation.cause.code {
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ObligationCauseCode::BuiltinDerivedObligation(..) |
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ObligationCauseCode::ImplDerivedObligation(..) => false,
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_ => true
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};
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if direct {
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// this is a "direct", user-specified, rather than derived,
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// obligation.
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flags.push(("direct", None));
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}
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if let ObligationCauseCode::ItemObligation(item) = obligation.cause.code {
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// FIXME: maybe also have some way of handling methods
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// from other traits? That would require name resolution,
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// which we might want to be some sort of hygienic.
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//
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// Currently I'm leaving it for what I need for `try`.
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if self.tcx.trait_of_item(item) == Some(trait_ref.def_id) {
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method = self.tcx.item_name(item);
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flags.push(("from_method", None));
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flags.push(("from_method", Some(&*method)));
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}
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}
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|
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if let Some(k) = obligation.cause.span.compiler_desugaring_kind() {
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desugaring = k.as_symbol().as_str();
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flags.push(("from_desugaring", None));
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flags.push(("from_desugaring", Some(&*desugaring)));
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}
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|
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if let Ok(Some(command)) = OnUnimplementedDirective::of_item(
|
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self.tcx, trait_ref.def_id, def_id
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) {
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command.evaluate(self.tcx, trait_ref, &flags)
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} else {
|
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OnUnimplementedNote::empty()
|
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}
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}
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|
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fn find_similar_impl_candidates(&self,
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trait_ref: ty::PolyTraitRef<'tcx>)
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-> Vec<ty::TraitRef<'tcx>>
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{
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let simp = fast_reject::simplify_type(self.tcx,
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trait_ref.skip_binder().self_ty(),
|
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true);
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|
let mut impl_candidates = Vec::new();
|
|
|
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match simp {
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Some(simp) => self.tcx.for_each_impl(trait_ref.def_id(), |def_id| {
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let imp = self.tcx.impl_trait_ref(def_id).unwrap();
|
|
let imp_simp = fast_reject::simplify_type(self.tcx,
|
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imp.self_ty(),
|
|
true);
|
|
if let Some(imp_simp) = imp_simp {
|
|
if simp != imp_simp {
|
|
return;
|
|
}
|
|
}
|
|
impl_candidates.push(imp);
|
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}),
|
|
None => self.tcx.for_each_impl(trait_ref.def_id(), |def_id| {
|
|
impl_candidates.push(
|
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self.tcx.impl_trait_ref(def_id).unwrap());
|
|
})
|
|
};
|
|
impl_candidates
|
|
}
|
|
|
|
fn report_similar_impl_candidates(&self,
|
|
impl_candidates: Vec<ty::TraitRef<'tcx>>,
|
|
err: &mut DiagnosticBuilder)
|
|
{
|
|
if impl_candidates.is_empty() {
|
|
return;
|
|
}
|
|
|
|
let end = if impl_candidates.len() <= 5 {
|
|
impl_candidates.len()
|
|
} else {
|
|
4
|
|
};
|
|
err.help(&format!("the following implementations were found:{}{}",
|
|
&impl_candidates[0..end].iter().map(|candidate| {
|
|
format!("\n {:?}", candidate)
|
|
}).collect::<String>(),
|
|
if impl_candidates.len() > 5 {
|
|
format!("\nand {} others", impl_candidates.len() - 4)
|
|
} else {
|
|
"".to_owned()
|
|
}
|
|
));
|
|
}
|
|
|
|
/// Reports that an overflow has occurred and halts compilation. We
|
|
/// halt compilation unconditionally because it is important that
|
|
/// overflows never be masked -- they basically represent computations
|
|
/// whose result could not be truly determined and thus we can't say
|
|
/// if the program type checks or not -- and they are unusual
|
|
/// occurrences in any case.
|
|
pub fn report_overflow_error<T>(&self,
|
|
obligation: &Obligation<'tcx, T>,
|
|
suggest_increasing_limit: bool) -> !
|
|
where T: fmt::Display + TypeFoldable<'tcx>
|
|
{
|
|
let predicate =
|
|
self.resolve_type_vars_if_possible(&obligation.predicate);
|
|
let mut err = struct_span_err!(self.tcx.sess, obligation.cause.span, E0275,
|
|
"overflow evaluating the requirement `{}`",
|
|
predicate);
|
|
|
|
if suggest_increasing_limit {
|
|
self.suggest_new_overflow_limit(&mut err);
|
|
}
|
|
|
|
self.note_obligation_cause(&mut err, obligation);
|
|
|
|
err.emit();
|
|
self.tcx.sess.abort_if_errors();
|
|
bug!();
|
|
}
|
|
|
|
/// Reports that a cycle was detected which led to overflow and halts
|
|
/// compilation. This is equivalent to `report_overflow_error` except
|
|
/// that we can give a more helpful error message (and, in particular,
|
|
/// we do not suggest increasing the overflow limit, which is not
|
|
/// going to help).
|
|
pub fn report_overflow_error_cycle(&self, cycle: &[PredicateObligation<'tcx>]) -> ! {
|
|
let cycle = self.resolve_type_vars_if_possible(&cycle.to_owned());
|
|
assert!(cycle.len() > 0);
|
|
|
|
debug!("report_overflow_error_cycle: cycle={:?}", cycle);
|
|
|
|
self.report_overflow_error(&cycle[0], false);
|
|
}
|
|
|
|
pub fn report_extra_impl_obligation(&self,
|
|
error_span: Span,
|
|
item_name: ast::Name,
|
|
_impl_item_def_id: DefId,
|
|
trait_item_def_id: DefId,
|
|
requirement: &fmt::Display)
|
|
-> DiagnosticBuilder<'tcx>
|
|
{
|
|
let msg = "impl has stricter requirements than trait";
|
|
let sp = self.tcx.sess.codemap().def_span(error_span);
|
|
|
|
let mut err = struct_span_err!(self.tcx.sess, sp, E0276, "{}", msg);
|
|
|
|
if let Some(trait_item_span) = self.tcx.hir.span_if_local(trait_item_def_id) {
|
|
let span = self.tcx.sess.codemap().def_span(trait_item_span);
|
|
err.span_label(span, format!("definition of `{}` from trait", item_name));
|
|
}
|
|
|
|
err.span_label(sp, format!("impl has extra requirement {}", requirement));
|
|
|
|
err
|
|
}
|
|
|
|
|
|
/// Get the parent trait chain start
|
|
fn get_parent_trait_ref(&self, code: &ObligationCauseCode<'tcx>) -> Option<String> {
|
|
match code {
|
|
&ObligationCauseCode::BuiltinDerivedObligation(ref data) => {
|
|
let parent_trait_ref = self.resolve_type_vars_if_possible(
|
|
&data.parent_trait_ref);
|
|
match self.get_parent_trait_ref(&data.parent_code) {
|
|
Some(t) => Some(t),
|
|
None => Some(format!("{}", parent_trait_ref.0.self_ty())),
|
|
}
|
|
}
|
|
_ => None,
|
|
}
|
|
}
|
|
|
|
pub fn report_selection_error(&self,
|
|
obligation: &PredicateObligation<'tcx>,
|
|
error: &SelectionError<'tcx>)
|
|
{
|
|
let span = obligation.cause.span;
|
|
|
|
let mut err = match *error {
|
|
SelectionError::Unimplemented => {
|
|
if let ObligationCauseCode::CompareImplMethodObligation {
|
|
item_name, impl_item_def_id, trait_item_def_id,
|
|
} = obligation.cause.code {
|
|
self.report_extra_impl_obligation(
|
|
span,
|
|
item_name,
|
|
impl_item_def_id,
|
|
trait_item_def_id,
|
|
&format!("`{}`", obligation.predicate))
|
|
.emit();
|
|
return;
|
|
}
|
|
match obligation.predicate {
|
|
ty::Predicate::Trait(ref trait_predicate) => {
|
|
let trait_predicate =
|
|
self.resolve_type_vars_if_possible(trait_predicate);
|
|
|
|
if self.tcx.sess.has_errors() && trait_predicate.references_error() {
|
|
return;
|
|
}
|
|
let trait_ref = trait_predicate.to_poly_trait_ref();
|
|
let (post_message, pre_message) =
|
|
self.get_parent_trait_ref(&obligation.cause.code)
|
|
.map(|t| (format!(" in `{}`", t), format!("within `{}`, ", t)))
|
|
.unwrap_or((String::new(), String::new()));
|
|
|
|
let OnUnimplementedNote { message, label }
|
|
= self.on_unimplemented_note(trait_ref, obligation);
|
|
let have_alt_message = message.is_some() || label.is_some();
|
|
|
|
let mut err = struct_span_err!(
|
|
self.tcx.sess,
|
|
span,
|
|
E0277,
|
|
"{}",
|
|
message.unwrap_or_else(|| {
|
|
format!("the trait bound `{}` is not satisfied{}",
|
|
trait_ref.to_predicate(), post_message)
|
|
}));
|
|
|
|
if let Some(ref s) = label {
|
|
// If it has a custom "#[rustc_on_unimplemented]"
|
|
// error message, let's display it as the label!
|
|
err.span_label(span, s.as_str());
|
|
err.help(&format!("{}the trait `{}` is not implemented for `{}`",
|
|
pre_message,
|
|
trait_ref,
|
|
trait_ref.self_ty()));
|
|
} else {
|
|
err.span_label(span,
|
|
&*format!("{}the trait `{}` is not implemented for `{}`",
|
|
pre_message,
|
|
trait_ref,
|
|
trait_ref.self_ty()));
|
|
}
|
|
|
|
self.suggest_borrow_on_unsized_slice(&obligation.cause.code, &mut err);
|
|
|
|
// Try to report a help message
|
|
if !trait_ref.has_infer_types() &&
|
|
self.predicate_can_apply(obligation.param_env, trait_ref) {
|
|
// If a where-clause may be useful, remind the
|
|
// user that they can add it.
|
|
//
|
|
// don't display an on-unimplemented note, as
|
|
// these notes will often be of the form
|
|
// "the type `T` can't be frobnicated"
|
|
// which is somewhat confusing.
|
|
err.help(&format!("consider adding a `where {}` bound",
|
|
trait_ref.to_predicate()));
|
|
} else if !have_alt_message {
|
|
// Can't show anything else useful, try to find similar impls.
|
|
let impl_candidates = self.find_similar_impl_candidates(trait_ref);
|
|
self.report_similar_impl_candidates(impl_candidates, &mut err);
|
|
}
|
|
|
|
err
|
|
}
|
|
|
|
ty::Predicate::Subtype(ref predicate) => {
|
|
// Errors for Subtype predicates show up as
|
|
// `FulfillmentErrorCode::CodeSubtypeError`,
|
|
// not selection error.
|
|
span_bug!(span, "subtype requirement gave wrong error: `{:?}`", predicate)
|
|
}
|
|
|
|
ty::Predicate::Equate(ref predicate) => {
|
|
let predicate = self.resolve_type_vars_if_possible(predicate);
|
|
let err = self.equality_predicate(&obligation.cause,
|
|
obligation.param_env,
|
|
&predicate).err().unwrap();
|
|
struct_span_err!(self.tcx.sess, span, E0278,
|
|
"the requirement `{}` is not satisfied (`{}`)",
|
|
predicate, err)
|
|
}
|
|
|
|
ty::Predicate::RegionOutlives(ref predicate) => {
|
|
let predicate = self.resolve_type_vars_if_possible(predicate);
|
|
let err = self.region_outlives_predicate(&obligation.cause,
|
|
&predicate).err().unwrap();
|
|
struct_span_err!(self.tcx.sess, span, E0279,
|
|
"the requirement `{}` is not satisfied (`{}`)",
|
|
predicate, err)
|
|
}
|
|
|
|
ty::Predicate::Projection(..) | ty::Predicate::TypeOutlives(..) => {
|
|
let predicate =
|
|
self.resolve_type_vars_if_possible(&obligation.predicate);
|
|
struct_span_err!(self.tcx.sess, span, E0280,
|
|
"the requirement `{}` is not satisfied",
|
|
predicate)
|
|
}
|
|
|
|
ty::Predicate::ObjectSafe(trait_def_id) => {
|
|
let violations = self.tcx.object_safety_violations(trait_def_id);
|
|
self.tcx.report_object_safety_error(span,
|
|
trait_def_id,
|
|
violations)
|
|
}
|
|
|
|
ty::Predicate::ClosureKind(closure_def_id, closure_substs, kind) => {
|
|
let found_kind = self.closure_kind(closure_def_id, closure_substs).unwrap();
|
|
let closure_span = self.tcx.sess.codemap()
|
|
.def_span(self.tcx.hir.span_if_local(closure_def_id).unwrap());
|
|
let node_id = self.tcx.hir.as_local_node_id(closure_def_id).unwrap();
|
|
let mut err = struct_span_err!(
|
|
self.tcx.sess, closure_span, E0525,
|
|
"expected a closure that implements the `{}` trait, \
|
|
but this closure only implements `{}`",
|
|
kind,
|
|
found_kind);
|
|
|
|
err.span_label(
|
|
closure_span,
|
|
format!("this closure implements `{}`, not `{}`", found_kind, kind));
|
|
err.span_label(
|
|
obligation.cause.span,
|
|
format!("the requirement to implement `{}` derives from here", kind));
|
|
|
|
// Additional context information explaining why the closure only implements
|
|
// a particular trait.
|
|
if let Some(tables) = self.in_progress_tables {
|
|
let tables = tables.borrow();
|
|
let closure_hir_id = self.tcx.hir.node_to_hir_id(node_id);
|
|
match (found_kind, tables.closure_kind_origins().get(closure_hir_id)) {
|
|
(ty::ClosureKind::FnOnce, Some((span, name))) => {
|
|
err.span_label(*span, format!(
|
|
"closure is `FnOnce` because it moves the \
|
|
variable `{}` out of its environment", name));
|
|
},
|
|
(ty::ClosureKind::FnMut, Some((span, name))) => {
|
|
err.span_label(*span, format!(
|
|
"closure is `FnMut` because it mutates the \
|
|
variable `{}` here", name));
|
|
},
|
|
_ => {}
|
|
}
|
|
}
|
|
|
|
err.emit();
|
|
return;
|
|
}
|
|
|
|
ty::Predicate::WellFormed(ty) => {
|
|
// WF predicates cannot themselves make
|
|
// errors. They can only block due to
|
|
// ambiguity; otherwise, they always
|
|
// degenerate into other obligations
|
|
// (which may fail).
|
|
span_bug!(span, "WF predicate not satisfied for {:?}", ty);
|
|
}
|
|
|
|
ty::Predicate::ConstEvaluatable(..) => {
|
|
// Errors for `ConstEvaluatable` predicates show up as
|
|
// `SelectionError::ConstEvalFailure`,
|
|
// not `Unimplemented`.
|
|
span_bug!(span,
|
|
"const-evaluatable requirement gave wrong error: `{:?}`", obligation)
|
|
}
|
|
}
|
|
}
|
|
|
|
OutputTypeParameterMismatch(ref found_trait_ref, ref expected_trait_ref, _) => {
|
|
let found_trait_ref = self.resolve_type_vars_if_possible(&*found_trait_ref);
|
|
let expected_trait_ref = self.resolve_type_vars_if_possible(&*expected_trait_ref);
|
|
if expected_trait_ref.self_ty().references_error() {
|
|
return;
|
|
}
|
|
let found_trait_ty = found_trait_ref.self_ty();
|
|
|
|
let found_did = found_trait_ty.ty_to_def_id();
|
|
let found_span = found_did.and_then(|did| {
|
|
self.tcx.hir.span_if_local(did)
|
|
}).map(|sp| self.tcx.sess.codemap().def_span(sp)); // the sp could be an fn def
|
|
|
|
let found = match found_trait_ref.skip_binder().substs.type_at(1).sty {
|
|
ty::TyTuple(ref tys, _) => tys.iter()
|
|
.map(|_| ArgKind::empty()).collect::<Vec<_>>(),
|
|
_ => vec![ArgKind::empty()],
|
|
};
|
|
let expected = match expected_trait_ref.skip_binder().substs.type_at(1).sty {
|
|
ty::TyTuple(ref tys, _) => tys.iter()
|
|
.map(|t| match t.sty {
|
|
ty::TypeVariants::TyTuple(ref tys, _) => ArgKind::Tuple(
|
|
span,
|
|
tys.iter()
|
|
.map(|ty| ("_".to_owned(), format!("{}", ty.sty)))
|
|
.collect::<Vec<_>>()
|
|
),
|
|
_ => ArgKind::Arg("_".to_owned(), format!("{}", t.sty)),
|
|
}).collect(),
|
|
ref sty => vec![ArgKind::Arg("_".to_owned(), format!("{}", sty))],
|
|
};
|
|
if found.len()== expected.len() {
|
|
self.report_closure_arg_mismatch(span,
|
|
found_span,
|
|
found_trait_ref,
|
|
expected_trait_ref)
|
|
} else {
|
|
let (closure_span, found) = found_did
|
|
.and_then(|did| self.tcx.hir.get_if_local(did))
|
|
.map(|node| {
|
|
let (found_span, found) = self.get_fn_like_arguments(node);
|
|
(Some(found_span), found)
|
|
}).unwrap_or((found_span, found));
|
|
|
|
self.report_arg_count_mismatch(span,
|
|
closure_span,
|
|
expected,
|
|
found,
|
|
found_trait_ty.is_closure())
|
|
}
|
|
}
|
|
|
|
TraitNotObjectSafe(did) => {
|
|
let violations = self.tcx.object_safety_violations(did);
|
|
self.tcx.report_object_safety_error(span, did,
|
|
violations)
|
|
}
|
|
|
|
ConstEvalFailure(ref err) => {
|
|
if let const_val::ErrKind::TypeckError = err.kind {
|
|
return;
|
|
}
|
|
err.struct_error(self.tcx, span, "constant expression")
|
|
}
|
|
};
|
|
self.note_obligation_cause(&mut err, obligation);
|
|
err.emit();
|
|
}
|
|
|
|
/// When encountering an assignment of an unsized trait, like `let x = ""[..];`, provide a
|
|
/// suggestion to borrow the initializer in order to use have a slice instead.
|
|
fn suggest_borrow_on_unsized_slice(&self,
|
|
code: &ObligationCauseCode<'tcx>,
|
|
err: &mut DiagnosticBuilder<'tcx>) {
|
|
if let &ObligationCauseCode::VariableType(node_id) = code {
|
|
let parent_node = self.tcx.hir.get_parent_node(node_id);
|
|
if let Some(hir::map::NodeLocal(ref local)) = self.tcx.hir.find(parent_node) {
|
|
if let Some(ref expr) = local.init {
|
|
if let hir::ExprIndex(_, _) = expr.node {
|
|
if let Ok(snippet) = self.tcx.sess.codemap().span_to_snippet(expr.span) {
|
|
err.span_suggestion(expr.span,
|
|
"consider borrowing here",
|
|
format!("&{}", snippet));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn get_fn_like_arguments(&self, node: hir::map::Node) -> (Span, Vec<ArgKind>) {
|
|
match node {
|
|
hir::map::NodeExpr(&hir::Expr {
|
|
node: hir::ExprClosure(_, ref _decl, id, span, _),
|
|
..
|
|
}) => {
|
|
(self.tcx.sess.codemap().def_span(span), self.tcx.hir.body(id).arguments.iter()
|
|
.map(|arg| {
|
|
if let hir::Pat {
|
|
node: hir::PatKind::Tuple(args, _),
|
|
span,
|
|
..
|
|
} = arg.pat.clone().into_inner() {
|
|
ArgKind::Tuple(
|
|
span,
|
|
args.iter().map(|pat| {
|
|
let snippet = self.tcx.sess.codemap()
|
|
.span_to_snippet(pat.span).unwrap();
|
|
(snippet, "_".to_owned())
|
|
}).collect::<Vec<_>>(),
|
|
)
|
|
} else {
|
|
let name = self.tcx.sess.codemap()
|
|
.span_to_snippet(arg.pat.span).unwrap();
|
|
ArgKind::Arg(name, "_".to_owned())
|
|
}
|
|
})
|
|
.collect::<Vec<ArgKind>>())
|
|
}
|
|
hir::map::NodeItem(&hir::Item {
|
|
span,
|
|
node: hir::ItemFn(ref decl, ..),
|
|
..
|
|
}) |
|
|
hir::map::NodeImplItem(&hir::ImplItem {
|
|
span,
|
|
node: hir::ImplItemKind::Method(hir::MethodSig { ref decl, .. }, _),
|
|
..
|
|
}) |
|
|
hir::map::NodeTraitItem(&hir::TraitItem {
|
|
span,
|
|
node: hir::TraitItemKind::Method(hir::MethodSig { ref decl, .. }, _),
|
|
..
|
|
}) => {
|
|
(self.tcx.sess.codemap().def_span(span), decl.inputs.iter()
|
|
.map(|arg| match arg.clone().into_inner().node {
|
|
hir::TyTup(ref tys) => ArgKind::Tuple(
|
|
arg.span,
|
|
tys.iter()
|
|
.map(|_| ("_".to_owned(), "_".to_owned()))
|
|
.collect::<Vec<_>>(),
|
|
),
|
|
_ => ArgKind::Arg("_".to_owned(), "_".to_owned())
|
|
}).collect::<Vec<ArgKind>>())
|
|
}
|
|
_ => panic!("non-FnLike node found: {:?}", node),
|
|
}
|
|
}
|
|
|
|
fn report_arg_count_mismatch(
|
|
&self,
|
|
span: Span,
|
|
found_span: Option<Span>,
|
|
expected_args: Vec<ArgKind>,
|
|
found_args: Vec<ArgKind>,
|
|
is_closure: bool,
|
|
) -> DiagnosticBuilder<'tcx> {
|
|
let kind = if is_closure { "closure" } else { "function" };
|
|
|
|
let args_str = |arguments: &Vec<ArgKind>, other: &Vec<ArgKind>| {
|
|
let arg_length = arguments.len();
|
|
let distinct = match &other[..] {
|
|
&[ArgKind::Tuple(..)] => true,
|
|
_ => false,
|
|
};
|
|
match (arg_length, arguments.get(0)) {
|
|
(1, Some(&ArgKind::Tuple(_, ref fields))) => {
|
|
format!("a single {}-tuple as argument", fields.len())
|
|
}
|
|
_ => format!("{} {}argument{}",
|
|
arg_length,
|
|
if distinct && arg_length > 1 { "distinct " } else { "" },
|
|
if arg_length == 1 { "" } else { "s" }),
|
|
}
|
|
};
|
|
|
|
let expected_str = args_str(&expected_args, &found_args);
|
|
let found_str = args_str(&found_args, &expected_args);
|
|
|
|
let mut err = struct_span_err!(
|
|
self.tcx.sess,
|
|
span,
|
|
E0593,
|
|
"{} is expected to take {}, but it takes {}",
|
|
kind,
|
|
expected_str,
|
|
found_str,
|
|
);
|
|
|
|
err.span_label(span, format!( "expected {} that takes {}", kind, expected_str));
|
|
|
|
if let Some(found_span) = found_span {
|
|
err.span_label(found_span, format!("takes {}", found_str));
|
|
|
|
if let &[ArgKind::Tuple(_, ref fields)] = &found_args[..] {
|
|
if fields.len() == expected_args.len() {
|
|
let sugg = fields.iter()
|
|
.map(|(name, _)| name.to_owned())
|
|
.collect::<Vec<String>>().join(", ");
|
|
err.span_suggestion(found_span,
|
|
"change the closure to take multiple arguments instead of \
|
|
a single tuple",
|
|
format!("|{}|", sugg));
|
|
}
|
|
}
|
|
if let &[ArgKind::Tuple(_, ref fields)] = &expected_args[..] {
|
|
if fields.len() == found_args.len() && is_closure {
|
|
let sugg = format!(
|
|
"|({}){}|",
|
|
found_args.iter()
|
|
.map(|arg| match arg {
|
|
ArgKind::Arg(name, _) => name.to_owned(),
|
|
_ => "_".to_owned(),
|
|
})
|
|
.collect::<Vec<String>>()
|
|
.join(", "),
|
|
// add type annotations if available
|
|
if found_args.iter().any(|arg| match arg {
|
|
ArgKind::Arg(_, ty) => ty != "_",
|
|
_ => false,
|
|
}) {
|
|
format!(": ({})",
|
|
fields.iter()
|
|
.map(|(_, ty)| ty.to_owned())
|
|
.collect::<Vec<String>>()
|
|
.join(", "))
|
|
} else {
|
|
"".to_owned()
|
|
},
|
|
);
|
|
err.span_suggestion(found_span,
|
|
"change the closure to accept a tuple instead of \
|
|
individual arguments",
|
|
sugg);
|
|
}
|
|
}
|
|
}
|
|
|
|
err
|
|
}
|
|
|
|
fn report_closure_arg_mismatch(&self,
|
|
span: Span,
|
|
found_span: Option<Span>,
|
|
expected_ref: ty::PolyTraitRef<'tcx>,
|
|
found: ty::PolyTraitRef<'tcx>)
|
|
-> DiagnosticBuilder<'tcx>
|
|
{
|
|
fn build_fn_sig_string<'a, 'gcx, 'tcx>(tcx: ty::TyCtxt<'a, 'gcx, 'tcx>,
|
|
trait_ref: &ty::TraitRef<'tcx>) -> String {
|
|
let inputs = trait_ref.substs.type_at(1);
|
|
let sig = if let ty::TyTuple(inputs, _) = inputs.sty {
|
|
tcx.mk_fn_sig(
|
|
inputs.iter().map(|&x| x),
|
|
tcx.mk_infer(ty::TyVar(ty::TyVid { index: 0 })),
|
|
false,
|
|
hir::Unsafety::Normal,
|
|
::syntax::abi::Abi::Rust
|
|
)
|
|
} else {
|
|
tcx.mk_fn_sig(
|
|
::std::iter::once(inputs),
|
|
tcx.mk_infer(ty::TyVar(ty::TyVid { index: 0 })),
|
|
false,
|
|
hir::Unsafety::Normal,
|
|
::syntax::abi::Abi::Rust
|
|
)
|
|
};
|
|
format!("{}", ty::Binder(sig))
|
|
}
|
|
|
|
let argument_is_closure = expected_ref.skip_binder().substs.type_at(0).is_closure();
|
|
let mut err = struct_span_err!(self.tcx.sess, span, E0631,
|
|
"type mismatch in {} arguments",
|
|
if argument_is_closure { "closure" } else { "function" });
|
|
|
|
let found_str = format!(
|
|
"expected signature of `{}`",
|
|
build_fn_sig_string(self.tcx, found.skip_binder())
|
|
);
|
|
err.span_label(span, found_str);
|
|
|
|
let found_span = found_span.unwrap_or(span);
|
|
let expected_str = format!(
|
|
"found signature of `{}`",
|
|
build_fn_sig_string(self.tcx, expected_ref.skip_binder())
|
|
);
|
|
err.span_label(found_span, expected_str);
|
|
|
|
err
|
|
}
|
|
}
|
|
|
|
impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
|
|
pub fn recursive_type_with_infinite_size_error(self,
|
|
type_def_id: DefId)
|
|
-> DiagnosticBuilder<'tcx>
|
|
{
|
|
assert!(type_def_id.is_local());
|
|
let span = self.hir.span_if_local(type_def_id).unwrap();
|
|
let span = self.sess.codemap().def_span(span);
|
|
let mut err = struct_span_err!(self.sess, span, E0072,
|
|
"recursive type `{}` has infinite size",
|
|
self.item_path_str(type_def_id));
|
|
err.span_label(span, "recursive type has infinite size");
|
|
err.help(&format!("insert indirection (e.g., a `Box`, `Rc`, or `&`) \
|
|
at some point to make `{}` representable",
|
|
self.item_path_str(type_def_id)));
|
|
err
|
|
}
|
|
|
|
pub fn report_object_safety_error(self,
|
|
span: Span,
|
|
trait_def_id: DefId,
|
|
violations: Vec<ObjectSafetyViolation>)
|
|
-> DiagnosticBuilder<'tcx>
|
|
{
|
|
let trait_str = self.item_path_str(trait_def_id);
|
|
let span = self.sess.codemap().def_span(span);
|
|
let mut err = struct_span_err!(
|
|
self.sess, span, E0038,
|
|
"the trait `{}` cannot be made into an object",
|
|
trait_str);
|
|
err.span_label(span, format!("the trait `{}` cannot be made into an object", trait_str));
|
|
|
|
let mut reported_violations = FxHashSet();
|
|
for violation in violations {
|
|
if !reported_violations.insert(violation.clone()) {
|
|
continue;
|
|
}
|
|
err.note(&violation.error_msg());
|
|
}
|
|
err
|
|
}
|
|
}
|
|
|
|
impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
|
|
fn maybe_report_ambiguity(&self, obligation: &PredicateObligation<'tcx>,
|
|
body_id: Option<hir::BodyId>) {
|
|
// Unable to successfully determine, probably means
|
|
// insufficient type information, but could mean
|
|
// ambiguous impls. The latter *ought* to be a
|
|
// coherence violation, so we don't report it here.
|
|
|
|
let predicate = self.resolve_type_vars_if_possible(&obligation.predicate);
|
|
let span = obligation.cause.span;
|
|
|
|
debug!("maybe_report_ambiguity(predicate={:?}, obligation={:?})",
|
|
predicate,
|
|
obligation);
|
|
|
|
// Ambiguity errors are often caused as fallout from earlier
|
|
// errors. So just ignore them if this infcx is tainted.
|
|
if self.is_tainted_by_errors() {
|
|
return;
|
|
}
|
|
|
|
match predicate {
|
|
ty::Predicate::Trait(ref data) => {
|
|
let trait_ref = data.to_poly_trait_ref();
|
|
let self_ty = trait_ref.self_ty();
|
|
if predicate.references_error() {
|
|
return;
|
|
}
|
|
// Typically, this ambiguity should only happen if
|
|
// there are unresolved type inference variables
|
|
// (otherwise it would suggest a coherence
|
|
// failure). But given #21974 that is not necessarily
|
|
// the case -- we can have multiple where clauses that
|
|
// are only distinguished by a region, which results
|
|
// in an ambiguity even when all types are fully
|
|
// known, since we don't dispatch based on region
|
|
// relationships.
|
|
|
|
// This is kind of a hack: it frequently happens that some earlier
|
|
// error prevents types from being fully inferred, and then we get
|
|
// a bunch of uninteresting errors saying something like "<generic
|
|
// #0> doesn't implement Sized". It may even be true that we
|
|
// could just skip over all checks where the self-ty is an
|
|
// inference variable, but I was afraid that there might be an
|
|
// inference variable created, registered as an obligation, and
|
|
// then never forced by writeback, and hence by skipping here we'd
|
|
// be ignoring the fact that we don't KNOW the type works
|
|
// out. Though even that would probably be harmless, given that
|
|
// we're only talking about builtin traits, which are known to be
|
|
// inhabited. But in any case I just threw in this check for
|
|
// has_errors() to be sure that compilation isn't happening
|
|
// anyway. In that case, why inundate the user.
|
|
if !self.tcx.sess.has_errors() {
|
|
if
|
|
self.tcx.lang_items().sized_trait()
|
|
.map_or(false, |sized_id| sized_id == trait_ref.def_id())
|
|
{
|
|
self.need_type_info(body_id, span, self_ty);
|
|
} else {
|
|
let mut err = struct_span_err!(self.tcx.sess,
|
|
span, E0283,
|
|
"type annotations required: \
|
|
cannot resolve `{}`",
|
|
predicate);
|
|
self.note_obligation_cause(&mut err, obligation);
|
|
err.emit();
|
|
}
|
|
}
|
|
}
|
|
|
|
ty::Predicate::WellFormed(ty) => {
|
|
// Same hacky approach as above to avoid deluging user
|
|
// with error messages.
|
|
if !ty.references_error() && !self.tcx.sess.has_errors() {
|
|
self.need_type_info(body_id, span, ty);
|
|
}
|
|
}
|
|
|
|
ty::Predicate::Subtype(ref data) => {
|
|
if data.references_error() || self.tcx.sess.has_errors() {
|
|
// no need to overload user in such cases
|
|
} else {
|
|
let &SubtypePredicate { a_is_expected: _, a, b } = data.skip_binder();
|
|
// both must be type variables, or the other would've been instantiated
|
|
assert!(a.is_ty_var() && b.is_ty_var());
|
|
self.need_type_info(body_id,
|
|
obligation.cause.span,
|
|
a);
|
|
}
|
|
}
|
|
|
|
_ => {
|
|
if !self.tcx.sess.has_errors() {
|
|
let mut err = struct_span_err!(self.tcx.sess,
|
|
obligation.cause.span, E0284,
|
|
"type annotations required: \
|
|
cannot resolve `{}`",
|
|
predicate);
|
|
self.note_obligation_cause(&mut err, obligation);
|
|
err.emit();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Returns whether the trait predicate may apply for *some* assignment
|
|
/// to the type parameters.
|
|
fn predicate_can_apply(&self,
|
|
param_env: ty::ParamEnv<'tcx>,
|
|
pred: ty::PolyTraitRef<'tcx>)
|
|
-> bool {
|
|
struct ParamToVarFolder<'a, 'gcx: 'a+'tcx, 'tcx: 'a> {
|
|
infcx: &'a InferCtxt<'a, 'gcx, 'tcx>,
|
|
var_map: FxHashMap<Ty<'tcx>, Ty<'tcx>>
|
|
}
|
|
|
|
impl<'a, 'gcx, 'tcx> TypeFolder<'gcx, 'tcx> for ParamToVarFolder<'a, 'gcx, 'tcx> {
|
|
fn tcx<'b>(&'b self) -> TyCtxt<'b, 'gcx, 'tcx> { self.infcx.tcx }
|
|
|
|
fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
|
|
if let ty::TyParam(ty::ParamTy {name, ..}) = ty.sty {
|
|
let infcx = self.infcx;
|
|
self.var_map.entry(ty).or_insert_with(||
|
|
infcx.next_ty_var(
|
|
TypeVariableOrigin::TypeParameterDefinition(DUMMY_SP, name)))
|
|
} else {
|
|
ty.super_fold_with(self)
|
|
}
|
|
}
|
|
}
|
|
|
|
self.probe(|_| {
|
|
let mut selcx = SelectionContext::new(self);
|
|
|
|
let cleaned_pred = pred.fold_with(&mut ParamToVarFolder {
|
|
infcx: self,
|
|
var_map: FxHashMap()
|
|
});
|
|
|
|
let cleaned_pred = super::project::normalize(
|
|
&mut selcx,
|
|
param_env,
|
|
ObligationCause::dummy(),
|
|
&cleaned_pred
|
|
).value;
|
|
|
|
let obligation = Obligation::new(
|
|
ObligationCause::dummy(),
|
|
param_env,
|
|
cleaned_pred.to_predicate()
|
|
);
|
|
|
|
selcx.evaluate_obligation(&obligation)
|
|
})
|
|
}
|
|
|
|
fn note_obligation_cause<T>(&self,
|
|
err: &mut DiagnosticBuilder,
|
|
obligation: &Obligation<'tcx, T>)
|
|
where T: fmt::Display
|
|
{
|
|
self.note_obligation_cause_code(err,
|
|
&obligation.predicate,
|
|
&obligation.cause.code);
|
|
}
|
|
|
|
fn note_obligation_cause_code<T>(&self,
|
|
err: &mut DiagnosticBuilder,
|
|
predicate: &T,
|
|
cause_code: &ObligationCauseCode<'tcx>)
|
|
where T: fmt::Display
|
|
{
|
|
let tcx = self.tcx;
|
|
match *cause_code {
|
|
ObligationCauseCode::ExprAssignable |
|
|
ObligationCauseCode::MatchExpressionArm { .. } |
|
|
ObligationCauseCode::IfExpression |
|
|
ObligationCauseCode::IfExpressionWithNoElse |
|
|
ObligationCauseCode::EquatePredicate |
|
|
ObligationCauseCode::MainFunctionType |
|
|
ObligationCauseCode::StartFunctionType |
|
|
ObligationCauseCode::IntrinsicType |
|
|
ObligationCauseCode::MethodReceiver |
|
|
ObligationCauseCode::ReturnNoExpression |
|
|
ObligationCauseCode::MiscObligation => {
|
|
}
|
|
ObligationCauseCode::SliceOrArrayElem => {
|
|
err.note("slice and array elements must have `Sized` type");
|
|
}
|
|
ObligationCauseCode::TupleElem => {
|
|
err.note("only the last element of a tuple may have a dynamically sized type");
|
|
}
|
|
ObligationCauseCode::ProjectionWf(data) => {
|
|
err.note(&format!("required so that the projection `{}` is well-formed",
|
|
data));
|
|
}
|
|
ObligationCauseCode::ReferenceOutlivesReferent(ref_ty) => {
|
|
err.note(&format!("required so that reference `{}` does not outlive its referent",
|
|
ref_ty));
|
|
}
|
|
ObligationCauseCode::ObjectTypeBound(object_ty, region) => {
|
|
err.note(&format!("required so that the lifetime bound of `{}` for `{}` \
|
|
is satisfied",
|
|
region, object_ty));
|
|
}
|
|
ObligationCauseCode::ItemObligation(item_def_id) => {
|
|
let item_name = tcx.item_path_str(item_def_id);
|
|
let msg = format!("required by `{}`", item_name);
|
|
if let Some(sp) = tcx.hir.span_if_local(item_def_id) {
|
|
let sp = tcx.sess.codemap().def_span(sp);
|
|
err.span_note(sp, &msg);
|
|
} else {
|
|
err.note(&msg);
|
|
}
|
|
}
|
|
ObligationCauseCode::ObjectCastObligation(object_ty) => {
|
|
err.note(&format!("required for the cast to the object type `{}`",
|
|
self.ty_to_string(object_ty)));
|
|
}
|
|
ObligationCauseCode::RepeatVec => {
|
|
err.note("the `Copy` trait is required because the \
|
|
repeated element will be copied");
|
|
}
|
|
ObligationCauseCode::VariableType(_) => {
|
|
err.note("all local variables must have a statically known size");
|
|
}
|
|
ObligationCauseCode::SizedReturnType => {
|
|
err.note("the return type of a function must have a \
|
|
statically known size");
|
|
}
|
|
ObligationCauseCode::SizedYieldType => {
|
|
err.note("the yield type of a generator must have a \
|
|
statically known size");
|
|
}
|
|
ObligationCauseCode::AssignmentLhsSized => {
|
|
err.note("the left-hand-side of an assignment must have a statically known size");
|
|
}
|
|
ObligationCauseCode::TupleInitializerSized => {
|
|
err.note("tuples must have a statically known size to be initialized");
|
|
}
|
|
ObligationCauseCode::StructInitializerSized => {
|
|
err.note("structs must have a statically known size to be initialized");
|
|
}
|
|
ObligationCauseCode::FieldSized(ref item) => {
|
|
match *item {
|
|
AdtKind::Struct => {
|
|
err.note("only the last field of a struct may have a dynamically \
|
|
sized type");
|
|
}
|
|
AdtKind::Union => {
|
|
err.note("no field of a union may have a dynamically sized type");
|
|
}
|
|
AdtKind::Enum => {
|
|
err.note("no field of an enum variant may have a dynamically sized type");
|
|
}
|
|
}
|
|
}
|
|
ObligationCauseCode::ConstSized => {
|
|
err.note("constant expressions must have a statically known size");
|
|
}
|
|
ObligationCauseCode::SharedStatic => {
|
|
err.note("shared static variables must have a type that implements `Sync`");
|
|
}
|
|
ObligationCauseCode::BuiltinDerivedObligation(ref data) => {
|
|
let parent_trait_ref = self.resolve_type_vars_if_possible(&data.parent_trait_ref);
|
|
err.note(&format!("required because it appears within the type `{}`",
|
|
parent_trait_ref.0.self_ty()));
|
|
let parent_predicate = parent_trait_ref.to_predicate();
|
|
self.note_obligation_cause_code(err,
|
|
&parent_predicate,
|
|
&data.parent_code);
|
|
}
|
|
ObligationCauseCode::ImplDerivedObligation(ref data) => {
|
|
let parent_trait_ref = self.resolve_type_vars_if_possible(&data.parent_trait_ref);
|
|
err.note(
|
|
&format!("required because of the requirements on the impl of `{}` for `{}`",
|
|
parent_trait_ref,
|
|
parent_trait_ref.0.self_ty()));
|
|
let parent_predicate = parent_trait_ref.to_predicate();
|
|
self.note_obligation_cause_code(err,
|
|
&parent_predicate,
|
|
&data.parent_code);
|
|
}
|
|
ObligationCauseCode::CompareImplMethodObligation { .. } => {
|
|
err.note(
|
|
&format!("the requirement `{}` appears on the impl method \
|
|
but not on the corresponding trait method",
|
|
predicate));
|
|
}
|
|
ObligationCauseCode::ReturnType(_) |
|
|
ObligationCauseCode::BlockTailExpression(_) => (),
|
|
}
|
|
}
|
|
|
|
fn suggest_new_overflow_limit(&self, err: &mut DiagnosticBuilder) {
|
|
let current_limit = self.tcx.sess.recursion_limit.get();
|
|
let suggested_limit = current_limit * 2;
|
|
err.help(&format!("consider adding a `#![recursion_limit=\"{}\"]` attribute to your crate",
|
|
suggested_limit));
|
|
}
|
|
}
|
|
|
|
enum ArgKind {
|
|
Arg(String, String),
|
|
Tuple(Span, Vec<(String, String)>),
|
|
}
|
|
|
|
impl ArgKind {
|
|
fn empty() -> ArgKind {
|
|
ArgKind::Arg("_".to_owned(), "_".to_owned())
|
|
}
|
|
}
|