1644 lines
67 KiB
Rust
1644 lines
67 KiB
Rust
pub mod on_unimplemented;
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pub mod suggestions;
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use super::{
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ConstEvalFailure, EvaluationResult, FulfillmentError, FulfillmentErrorCode,
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MismatchedProjectionTypes, ObjectSafetyViolation, Obligation, ObligationCause,
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ObligationCauseCode, OnUnimplementedDirective, OnUnimplementedNote,
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OutputTypeParameterMismatch, Overflow, PredicateObligation, SelectionContext, SelectionError,
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TraitNotObjectSafe,
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};
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use crate::infer::error_reporting::{TyCategory, TypeAnnotationNeeded as ErrorCode};
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use crate::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
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use crate::infer::{self, InferCtxt, TyCtxtInferExt};
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use rustc::mir::interpret::ErrorHandled;
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use rustc::session::DiagnosticMessageId;
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use rustc::ty::error::ExpectedFound;
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use rustc::ty::fast_reject;
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use rustc::ty::fold::TypeFolder;
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use rustc::ty::SubtypePredicate;
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use rustc::ty::{
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self, AdtKind, ToPolyTraitRef, ToPredicate, Ty, TyCtxt, TypeFoldable, WithConstness,
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};
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use rustc_ast::ast;
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use rustc_data_structures::fx::{FxHashMap, FxHashSet};
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use rustc_errors::{struct_span_err, Applicability, DiagnosticBuilder};
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use rustc_hir as hir;
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use rustc_hir::def_id::{DefId, LOCAL_CRATE};
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use rustc_hir::{QPath, TyKind, WhereBoundPredicate, WherePredicate};
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use rustc_span::source_map::SourceMap;
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use rustc_span::{ExpnKind, Span, DUMMY_SP};
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use std::fmt;
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impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
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pub fn report_fulfillment_errors(
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&self,
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errors: &[FulfillmentError<'tcx>],
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body_id: Option<hir::BodyId>,
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fallback_has_occurred: bool,
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) {
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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<_, Vec<_>> = self
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.reported_trait_errors
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.borrow()
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.iter()
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.map(|(&span, predicates)| {
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(
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span,
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predicates
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.iter()
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.map(|&predicate| ErrorDescriptor { predicate, index: None })
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.collect(),
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)
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})
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.collect();
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for (index, error) in errors.iter().enumerate() {
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// We want to ignore desugarings here: spans are equivalent even
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// if one is the result of a desugaring and the other is not.
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let mut span = error.obligation.cause.span;
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let expn_data = span.ctxt().outer_expn_data();
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if let ExpnKind::Desugaring(_) = expn_data.kind {
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span = expn_data.call_site;
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}
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error_map.entry(span).or_default().push(ErrorDescriptor {
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predicate: error.obligation.predicate,
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index: Some(index),
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});
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self.reported_trait_errors
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.borrow_mut()
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.entry(span)
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.or_default()
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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, though
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// maybe it *is* better to sort errors by span or something.
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let mut is_suppressed = vec![false; errors.len()];
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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, fallback_has_occurred);
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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, cond: &ty::Predicate<'tcx>, error: &ty::Predicate<'tcx>) -> bool {
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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, _)) => (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]) {
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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();
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if self.can_sub(param_env, error, implication).is_ok() {
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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(
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&self,
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error: &FulfillmentError<'tcx>,
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body_id: Option<hir::BodyId>,
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fallback_has_occurred: bool,
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) {
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debug!("report_fulfillment_error({:?})", error);
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match error.code {
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FulfillmentErrorCode::CodeSelectionError(ref selection_error) => {
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self.report_selection_error(
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&error.obligation,
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selection_error,
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fallback_has_occurred,
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error.points_at_arg_span,
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);
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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(
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&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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)
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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(
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&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 = self.resolve_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_bound_vars_with_fresh_vars(
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obligation.cause.span,
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infer::LateBoundRegionConversionTime::HigherRankedType,
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data,
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);
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let mut obligations = vec![];
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let normalized_ty = 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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&mut obligations,
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);
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debug!(
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"report_projection_error obligation.cause={:?} obligation.param_env={:?}",
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obligation.cause, obligation.param_env
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);
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debug!(
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"report_projection_error normalized_ty={:?} data.ty={:?}",
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normalized_ty, data.ty
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);
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let is_normalized_ty_expected = match &obligation.cause.code {
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ObligationCauseCode::ItemObligation(_)
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| ObligationCauseCode::BindingObligation(_, _)
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| ObligationCauseCode::ObjectCastObligation(_) => false,
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_ => true,
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};
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if let Err(error) = self.at(&obligation.cause, obligation.param_env).eq_exp(
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is_normalized_ty_expected,
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normalized_ty,
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data.ty,
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) {
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values = Some(infer::ValuePairs::Types(ExpectedFound::new(
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is_normalized_ty_expected,
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normalized_ty,
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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), Some(obligation.cause.span), msg);
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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,
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obligation.cause.span,
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E0271,
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"type mismatch resolving `{}`",
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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(t: Ty<'_>) -> Option<u32> {
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match t.kind {
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ty::Bool => Some(0),
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ty::Char => Some(1),
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ty::Str => Some(2),
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ty::Int(..) | ty::Uint(..) | ty::Infer(ty::IntVar(..)) => Some(3),
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ty::Float(..) | ty::Infer(ty::FloatVar(..)) => Some(4),
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ty::Ref(..) | ty::RawPtr(..) => Some(5),
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ty::Array(..) | ty::Slice(..) => Some(6),
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ty::FnDef(..) | ty::FnPtr(..) => Some(7),
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ty::Dynamic(..) => Some(8),
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ty::Closure(..) => Some(9),
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ty::Tuple(..) => Some(10),
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ty::Projection(..) => Some(11),
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ty::Param(..) => Some(12),
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ty::Opaque(..) => Some(13),
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ty::Never => Some(14),
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ty::Adt(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::Generator(..) => Some(18),
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ty::Foreign(..) => Some(19),
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ty::GeneratorWitness(..) => Some(20),
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ty::Placeholder(..) | ty::Bound(..) | ty::Infer(..) | ty::Error => None,
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ty::UnnormalizedProjection(..) => bug!("only used with chalk-engine"),
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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.kind, &b.kind) {
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(&ty::Adt(def_a, _), &ty::Adt(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 describe_generator(&self, body_id: hir::BodyId) -> Option<&'static str> {
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self.tcx.hir().body(body_id).generator_kind.map(|gen_kind| match gen_kind {
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hir::GeneratorKind::Gen => "a generator",
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hir::GeneratorKind::Async(hir::AsyncGeneratorKind::Block) => "an async block",
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hir::GeneratorKind::Async(hir::AsyncGeneratorKind::Fn) => "an async function",
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hir::GeneratorKind::Async(hir::AsyncGeneratorKind::Closure) => "an async closure",
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})
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}
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fn find_similar_impl_candidates(
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&self,
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trait_ref: ty::PolyTraitRef<'tcx>,
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) -> Vec<ty::TraitRef<'tcx>> {
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let simp = fast_reject::simplify_type(self.tcx, trait_ref.skip_binder().self_ty(), true);
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let all_impls = self.tcx.all_impls(trait_ref.def_id());
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match simp {
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Some(simp) => all_impls
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.iter()
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.filter_map(|&def_id| {
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let imp = self.tcx.impl_trait_ref(def_id).unwrap();
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let imp_simp = fast_reject::simplify_type(self.tcx, imp.self_ty(), true);
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if let Some(imp_simp) = imp_simp {
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if simp != imp_simp {
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return None;
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}
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}
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Some(imp)
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})
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.collect(),
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None => {
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all_impls.iter().map(|&def_id| self.tcx.impl_trait_ref(def_id).unwrap()).collect()
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}
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}
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}
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fn report_similar_impl_candidates(
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&self,
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impl_candidates: Vec<ty::TraitRef<'tcx>>,
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err: &mut DiagnosticBuilder<'_>,
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) {
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if impl_candidates.is_empty() {
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return;
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}
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let len = impl_candidates.len();
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let end = if impl_candidates.len() <= 5 { impl_candidates.len() } else { 4 };
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|
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let normalize = |candidate| {
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self.tcx.infer_ctxt().enter(|ref infcx| {
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let normalized = infcx
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.at(&ObligationCause::dummy(), ty::ParamEnv::empty())
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.normalize(candidate)
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.ok();
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match normalized {
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Some(normalized) => format!("\n {:?}", normalized.value),
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None => format!("\n {:?}", candidate),
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}
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})
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};
|
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|
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// Sort impl candidates so that ordering is consistent for UI tests.
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let mut normalized_impl_candidates =
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impl_candidates.iter().map(normalize).collect::<Vec<String>>();
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|
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// Sort before taking the `..end` range,
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// because the ordering of `impl_candidates` may not be deterministic:
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// https://github.com/rust-lang/rust/pull/57475#issuecomment-455519507
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normalized_impl_candidates.sort();
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|
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err.help(&format!(
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"the following implementations were found:{}{}",
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normalized_impl_candidates[..end].join(""),
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if len > 5 { format!("\nand {} others", len - 4) } else { String::new() }
|
|
));
|
|
}
|
|
|
|
/// 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>(
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&self,
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obligation: &Obligation<'tcx, T>,
|
|
suggest_increasing_limit: bool,
|
|
) -> !
|
|
where
|
|
T: fmt::Display + TypeFoldable<'tcx>,
|
|
{
|
|
let predicate = self.resolve_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_code(
|
|
&mut err,
|
|
&obligation.predicate,
|
|
&obligation.cause.code,
|
|
&mut vec![],
|
|
);
|
|
|
|
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_vars_if_possible(&cycle.to_owned());
|
|
assert!(!cycle.is_empty());
|
|
|
|
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: &dyn fmt::Display,
|
|
) -> DiagnosticBuilder<'tcx> {
|
|
let msg = "impl has stricter requirements than trait";
|
|
let sp = self.tcx.sess.source_map().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.source_map().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
|
|
}
|
|
|
|
/// Gets the parent trait chain start
|
|
fn get_parent_trait_ref(
|
|
&self,
|
|
code: &ObligationCauseCode<'tcx>,
|
|
) -> Option<(String, Option<Span>)> {
|
|
match code {
|
|
&ObligationCauseCode::BuiltinDerivedObligation(ref data) => {
|
|
let parent_trait_ref = self.resolve_vars_if_possible(&data.parent_trait_ref);
|
|
match self.get_parent_trait_ref(&data.parent_code) {
|
|
Some(t) => Some(t),
|
|
None => {
|
|
let ty = parent_trait_ref.skip_binder().self_ty();
|
|
let span =
|
|
TyCategory::from_ty(ty).map(|(_, def_id)| self.tcx.def_span(def_id));
|
|
Some((ty.to_string(), span))
|
|
}
|
|
}
|
|
}
|
|
_ => None,
|
|
}
|
|
}
|
|
|
|
pub fn report_selection_error(
|
|
&self,
|
|
obligation: &PredicateObligation<'tcx>,
|
|
error: &SelectionError<'tcx>,
|
|
fallback_has_occurred: bool,
|
|
points_at_arg: bool,
|
|
) {
|
|
let tcx = self.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,
|
|
}
|
|
| ObligationCauseCode::CompareImplTypeObligation {
|
|
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_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, type_def) = self
|
|
.get_parent_trait_ref(&obligation.cause.code)
|
|
.map(|(t, s)| {
|
|
(
|
|
format!(" in `{}`", t),
|
|
format!("within `{}`, ", t),
|
|
s.map(|s| (format!("within this `{}`", t), s)),
|
|
)
|
|
})
|
|
.unwrap_or_default();
|
|
|
|
let OnUnimplementedNote { message, label, note, enclosing_scope } =
|
|
self.on_unimplemented_note(trait_ref, obligation);
|
|
let have_alt_message = message.is_some() || label.is_some();
|
|
let is_try = self
|
|
.tcx
|
|
.sess
|
|
.source_map()
|
|
.span_to_snippet(span)
|
|
.map(|s| &s == "?")
|
|
.unwrap_or(false);
|
|
let is_from = format!("{}", trait_ref.print_only_trait_path())
|
|
.starts_with("std::convert::From<");
|
|
let (message, note) = if is_try && is_from {
|
|
(
|
|
Some(format!(
|
|
"`?` couldn't convert the error to `{}`",
|
|
trait_ref.self_ty(),
|
|
)),
|
|
Some(
|
|
"the question mark operation (`?`) implicitly performs a \
|
|
conversion on the error value using the `From` trait"
|
|
.to_owned(),
|
|
),
|
|
)
|
|
} else {
|
|
(message, note)
|
|
};
|
|
|
|
let mut err = struct_span_err!(
|
|
self.tcx.sess,
|
|
span,
|
|
E0277,
|
|
"{}",
|
|
message.unwrap_or_else(|| format!(
|
|
"the trait bound `{}` is not satisfied{}",
|
|
trait_ref.without_const().to_predicate(),
|
|
post_message,
|
|
))
|
|
);
|
|
|
|
let explanation =
|
|
if obligation.cause.code == ObligationCauseCode::MainFunctionType {
|
|
"consider using `()`, or a `Result`".to_owned()
|
|
} else {
|
|
format!(
|
|
"{}the trait `{}` is not implemented for `{}`",
|
|
pre_message,
|
|
trait_ref.print_only_trait_path(),
|
|
trait_ref.self_ty(),
|
|
)
|
|
};
|
|
|
|
if self.suggest_add_reference_to_arg(
|
|
&obligation,
|
|
&mut err,
|
|
&trait_ref,
|
|
points_at_arg,
|
|
have_alt_message,
|
|
) {
|
|
self.note_obligation_cause(&mut err, obligation);
|
|
err.emit();
|
|
return;
|
|
}
|
|
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(&explanation);
|
|
} else {
|
|
err.span_label(span, explanation);
|
|
}
|
|
if let Some((msg, span)) = type_def {
|
|
err.span_label(span, &msg);
|
|
}
|
|
if let Some(ref s) = note {
|
|
// If it has a custom `#[rustc_on_unimplemented]` note, let's display it
|
|
err.note(s.as_str());
|
|
}
|
|
if let Some(ref s) = enclosing_scope {
|
|
let enclosing_scope_span = tcx.def_span(
|
|
tcx.hir()
|
|
.opt_local_def_id(obligation.cause.body_id)
|
|
.unwrap_or_else(|| {
|
|
tcx.hir().body_owner_def_id(hir::BodyId {
|
|
hir_id: obligation.cause.body_id,
|
|
})
|
|
}),
|
|
);
|
|
|
|
err.span_label(enclosing_scope_span, s.as_str());
|
|
}
|
|
|
|
self.suggest_borrow_on_unsized_slice(&obligation.cause.code, &mut err);
|
|
self.suggest_fn_call(&obligation, &mut err, &trait_ref, points_at_arg);
|
|
self.suggest_remove_reference(&obligation, &mut err, &trait_ref);
|
|
self.suggest_semicolon_removal(&obligation, &mut err, span, &trait_ref);
|
|
self.note_version_mismatch(&mut err, &trait_ref);
|
|
if self.suggest_impl_trait(&mut err, span, &obligation, &trait_ref) {
|
|
err.emit();
|
|
return;
|
|
}
|
|
|
|
// Try to report a help message
|
|
if !trait_ref.has_infer_types_or_consts()
|
|
&& 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.
|
|
self.suggest_restricting_param_bound(
|
|
&mut err,
|
|
&trait_ref,
|
|
obligation.cause.body_id,
|
|
);
|
|
} 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);
|
|
}
|
|
self.suggest_change_mut(
|
|
&obligation,
|
|
&mut err,
|
|
&trait_ref,
|
|
points_at_arg,
|
|
);
|
|
}
|
|
|
|
// If this error is due to `!: Trait` not implemented but `(): Trait` is
|
|
// implemented, and fallback has occurred, then it could be due to a
|
|
// variable that used to fallback to `()` now falling back to `!`. Issue a
|
|
// note informing about the change in behaviour.
|
|
if trait_predicate.skip_binder().self_ty().is_never()
|
|
&& fallback_has_occurred
|
|
{
|
|
let predicate = trait_predicate.map_bound(|mut trait_pred| {
|
|
trait_pred.trait_ref.substs = self.tcx.mk_substs_trait(
|
|
self.tcx.mk_unit(),
|
|
&trait_pred.trait_ref.substs[1..],
|
|
);
|
|
trait_pred
|
|
});
|
|
let unit_obligation = Obligation {
|
|
predicate: ty::Predicate::Trait(
|
|
predicate,
|
|
hir::Constness::NotConst,
|
|
),
|
|
..obligation.clone()
|
|
};
|
|
if self.predicate_may_hold(&unit_obligation) {
|
|
err.note(
|
|
"the trait is implemented for `()`. \
|
|
Possibly this error has been caused by changes to \
|
|
Rust's type-inference algorithm (see issue #48950 \
|
|
<https://github.com/rust-lang/rust/issues/48950> \
|
|
for more information). Consider whether you meant to use \
|
|
the type `()` here instead.",
|
|
);
|
|
}
|
|
}
|
|
|
|
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::RegionOutlives(ref predicate) => {
|
|
let predicate = self.resolve_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_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);
|
|
report_object_safety_error(self.tcx, 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
|
|
.source_map()
|
|
.def_span(self.tcx.hir().span_if_local(closure_def_id).unwrap());
|
|
let hir_id = self.tcx.hir().as_local_hir_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();
|
|
match (found_kind, tables.closure_kind_origins().get(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_vars_if_possible(&*found_trait_ref);
|
|
let expected_trait_ref = self.resolve_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 = match found_trait_ty.kind {
|
|
ty::Closure(did, _) | ty::Foreign(did) | ty::FnDef(did, _) => Some(did),
|
|
ty::Adt(def, _) => Some(def.did),
|
|
_ => None,
|
|
};
|
|
|
|
let found_span = found_did
|
|
.and_then(|did| self.tcx.hir().span_if_local(did))
|
|
.map(|sp| self.tcx.sess.source_map().def_span(sp)); // the sp could be an fn def
|
|
|
|
if self.reported_closure_mismatch.borrow().contains(&(span, found_span)) {
|
|
// We check closures twice, with obligations flowing in different directions,
|
|
// but we want to complain about them only once.
|
|
return;
|
|
}
|
|
|
|
self.reported_closure_mismatch.borrow_mut().insert((span, found_span));
|
|
|
|
let found = match found_trait_ref.skip_binder().substs.type_at(1).kind {
|
|
ty::Tuple(ref tys) => vec![ArgKind::empty(); tys.len()],
|
|
_ => vec![ArgKind::empty()],
|
|
};
|
|
|
|
let expected_ty = expected_trait_ref.skip_binder().substs.type_at(1);
|
|
let expected = match expected_ty.kind {
|
|
ty::Tuple(ref tys) => tys
|
|
.iter()
|
|
.map(|t| ArgKind::from_expected_ty(t.expect_ty(), Some(span)))
|
|
.collect(),
|
|
_ => vec![ArgKind::Arg("_".to_owned(), expected_ty.to_string())],
|
|
};
|
|
|
|
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);
|
|
report_object_safety_error(self.tcx, span, did, violations)
|
|
}
|
|
|
|
ConstEvalFailure(ErrorHandled::TooGeneric) => {
|
|
// In this instance, we have a const expression containing an unevaluated
|
|
// generic parameter. We have no idea whether this expression is valid or
|
|
// not (e.g. it might result in an error), but we don't want to just assume
|
|
// that it's okay, because that might result in post-monomorphisation time
|
|
// errors. The onus is really on the caller to provide values that it can
|
|
// prove are well-formed.
|
|
let mut err = self
|
|
.tcx
|
|
.sess
|
|
.struct_span_err(span, "constant expression depends on a generic parameter");
|
|
// FIXME(const_generics): we should suggest to the user how they can resolve this
|
|
// issue. However, this is currently not actually possible
|
|
// (see https://github.com/rust-lang/rust/issues/66962#issuecomment-575907083).
|
|
err.note("this may fail depending on what value the parameter takes");
|
|
err
|
|
}
|
|
|
|
// Already reported in the query.
|
|
ConstEvalFailure(ErrorHandled::Reported) => {
|
|
self.tcx.sess.delay_span_bug(span, "constant in type had an ignored error");
|
|
return;
|
|
}
|
|
|
|
Overflow => {
|
|
bug!("overflow should be handled before the `report_selection_error` path");
|
|
}
|
|
};
|
|
|
|
self.note_obligation_cause(&mut err, obligation);
|
|
self.point_at_returns_when_relevant(&mut err, &obligation);
|
|
|
|
err.emit();
|
|
}
|
|
|
|
/// If the `Self` type of the unsatisfied trait `trait_ref` implements a trait
|
|
/// with the same path as `trait_ref`, a help message about
|
|
/// a probable version mismatch is added to `err`
|
|
fn note_version_mismatch(
|
|
&self,
|
|
err: &mut DiagnosticBuilder<'_>,
|
|
trait_ref: &ty::PolyTraitRef<'tcx>,
|
|
) {
|
|
let get_trait_impl = |trait_def_id| {
|
|
let mut trait_impl = None;
|
|
self.tcx.for_each_relevant_impl(trait_def_id, trait_ref.self_ty(), |impl_def_id| {
|
|
if trait_impl.is_none() {
|
|
trait_impl = Some(impl_def_id);
|
|
}
|
|
});
|
|
trait_impl
|
|
};
|
|
let required_trait_path = self.tcx.def_path_str(trait_ref.def_id());
|
|
let all_traits = self.tcx.all_traits(LOCAL_CRATE);
|
|
let traits_with_same_path: std::collections::BTreeSet<_> = all_traits
|
|
.iter()
|
|
.filter(|trait_def_id| **trait_def_id != trait_ref.def_id())
|
|
.filter(|trait_def_id| self.tcx.def_path_str(**trait_def_id) == required_trait_path)
|
|
.collect();
|
|
for trait_with_same_path in traits_with_same_path {
|
|
if let Some(impl_def_id) = get_trait_impl(*trait_with_same_path) {
|
|
let impl_span = self.tcx.def_span(impl_def_id);
|
|
err.span_help(impl_span, "trait impl with same name found");
|
|
let trait_crate = self.tcx.crate_name(trait_with_same_path.krate);
|
|
let crate_msg = format!(
|
|
"perhaps two different versions of crate `{}` are being used?",
|
|
trait_crate
|
|
);
|
|
err.note(&crate_msg);
|
|
}
|
|
}
|
|
}
|
|
|
|
fn mk_obligation_for_def_id(
|
|
&self,
|
|
def_id: DefId,
|
|
output_ty: Ty<'tcx>,
|
|
cause: ObligationCause<'tcx>,
|
|
param_env: ty::ParamEnv<'tcx>,
|
|
) -> PredicateObligation<'tcx> {
|
|
let new_trait_ref =
|
|
ty::TraitRef { def_id, substs: self.tcx.mk_substs_trait(output_ty, &[]) };
|
|
Obligation::new(cause, param_env, new_trait_ref.without_const().to_predicate())
|
|
}
|
|
}
|
|
|
|
pub fn recursive_type_with_infinite_size_error(
|
|
tcx: TyCtxt<'tcx>,
|
|
type_def_id: DefId,
|
|
) -> DiagnosticBuilder<'tcx> {
|
|
assert!(type_def_id.is_local());
|
|
let span = tcx.hir().span_if_local(type_def_id).unwrap();
|
|
let span = tcx.sess.source_map().def_span(span);
|
|
let mut err = struct_span_err!(
|
|
tcx.sess,
|
|
span,
|
|
E0072,
|
|
"recursive type `{}` has infinite size",
|
|
tcx.def_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",
|
|
tcx.def_path_str(type_def_id)
|
|
));
|
|
err
|
|
}
|
|
|
|
pub fn report_object_safety_error(
|
|
tcx: TyCtxt<'tcx>,
|
|
span: Span,
|
|
trait_def_id: DefId,
|
|
violations: Vec<ObjectSafetyViolation>,
|
|
) -> DiagnosticBuilder<'tcx> {
|
|
let trait_str = tcx.def_path_str(trait_def_id);
|
|
let trait_span = tcx.hir().get_if_local(trait_def_id).and_then(|node| match node {
|
|
hir::Node::Item(item) => Some(item.ident.span),
|
|
_ => None,
|
|
});
|
|
let span = tcx.sess.source_map().def_span(span);
|
|
let mut err = struct_span_err!(
|
|
tcx.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::default();
|
|
let mut had_span_label = false;
|
|
for violation in violations {
|
|
if let ObjectSafetyViolation::SizedSelf(sp) = &violation {
|
|
if !sp.is_empty() {
|
|
// Do not report `SizedSelf` without spans pointing at `SizedSelf` obligations
|
|
// with a `Span`.
|
|
reported_violations.insert(ObjectSafetyViolation::SizedSelf(vec![].into()));
|
|
}
|
|
}
|
|
if reported_violations.insert(violation.clone()) {
|
|
let spans = violation.spans();
|
|
let msg = if trait_span.is_none() || spans.is_empty() {
|
|
format!("the trait cannot be made into an object because {}", violation.error_msg())
|
|
} else {
|
|
had_span_label = true;
|
|
format!("...because {}", violation.error_msg())
|
|
};
|
|
if spans.is_empty() {
|
|
err.note(&msg);
|
|
} else {
|
|
for span in spans {
|
|
err.span_label(span, &msg);
|
|
}
|
|
}
|
|
match (trait_span, violation.solution()) {
|
|
(Some(_), Some((note, None))) => {
|
|
err.help(¬e);
|
|
}
|
|
(Some(_), Some((note, Some((sugg, span))))) => {
|
|
err.span_suggestion(span, ¬e, sugg, Applicability::MachineApplicable);
|
|
}
|
|
// Only provide the help if its a local trait, otherwise it's not actionable.
|
|
_ => {}
|
|
}
|
|
}
|
|
}
|
|
if let (Some(trait_span), true) = (trait_span, had_span_label) {
|
|
err.span_label(trait_span, "this trait cannot be made into an object...");
|
|
}
|
|
|
|
if tcx.sess.trait_methods_not_found.borrow().contains(&span) {
|
|
// Avoid emitting error caused by non-existing method (#58734)
|
|
err.cancel();
|
|
}
|
|
|
|
err
|
|
}
|
|
|
|
impl<'a, 'tcx> InferCtxt<'a, '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_vars_if_possible(&obligation.predicate);
|
|
let span = obligation.cause.span;
|
|
|
|
debug!(
|
|
"maybe_report_ambiguity(predicate={:?}, obligation={:?} body_id={:?}, code={:?})",
|
|
predicate, obligation, body_id, obligation.cause.code,
|
|
);
|
|
|
|
// 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;
|
|
}
|
|
|
|
let mut err = match predicate {
|
|
ty::Predicate::Trait(ref data, _) => {
|
|
let trait_ref = data.to_poly_trait_ref();
|
|
let self_ty = trait_ref.self_ty();
|
|
debug!("self_ty {:?} {:?} trait_ref {:?}", self_ty, self_ty.kind, trait_ref);
|
|
|
|
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. We used to check for `self.tcx.sess.has_errors()` to
|
|
// avoid inundating the user with unnecessary errors, but we now
|
|
// check upstream for type errors and don't add the obligations to
|
|
// begin with in those cases.
|
|
if self
|
|
.tcx
|
|
.lang_items()
|
|
.sized_trait()
|
|
.map_or(false, |sized_id| sized_id == trait_ref.def_id())
|
|
{
|
|
self.need_type_info_err(body_id, span, self_ty, ErrorCode::E0282).emit();
|
|
return;
|
|
}
|
|
let mut err = self.need_type_info_err(body_id, span, self_ty, ErrorCode::E0283);
|
|
err.note(&format!("cannot resolve `{}`", predicate));
|
|
if let ObligationCauseCode::ItemObligation(def_id) = obligation.cause.code {
|
|
self.suggest_fully_qualified_path(&mut err, def_id, span, trait_ref.def_id());
|
|
} else if let (
|
|
Ok(ref snippet),
|
|
ObligationCauseCode::BindingObligation(ref def_id, _),
|
|
) =
|
|
(self.tcx.sess.source_map().span_to_snippet(span), &obligation.cause.code)
|
|
{
|
|
let generics = self.tcx.generics_of(*def_id);
|
|
if !generics.params.is_empty() && !snippet.ends_with('>') {
|
|
// FIXME: To avoid spurious suggestions in functions where type arguments
|
|
// where already supplied, we check the snippet to make sure it doesn't
|
|
// end with a turbofish. Ideally we would have access to a `PathSegment`
|
|
// instead. Otherwise we would produce the following output:
|
|
//
|
|
// error[E0283]: type annotations needed
|
|
// --> $DIR/issue-54954.rs:3:24
|
|
// |
|
|
// LL | const ARR_LEN: usize = Tt::const_val::<[i8; 123]>();
|
|
// | ^^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
// | |
|
|
// | cannot infer type
|
|
// | help: consider specifying the type argument
|
|
// | in the function call:
|
|
// | `Tt::const_val::<[i8; 123]>::<T>`
|
|
// ...
|
|
// LL | const fn const_val<T: Sized>() -> usize {
|
|
// | --------- - required by this bound in `Tt::const_val`
|
|
// |
|
|
// = note: cannot resolve `_: Tt`
|
|
|
|
err.span_suggestion(
|
|
span,
|
|
&format!(
|
|
"consider specifying the type argument{} in the function call",
|
|
if generics.params.len() > 1 { "s" } else { "" },
|
|
),
|
|
format!(
|
|
"{}::<{}>",
|
|
snippet,
|
|
generics
|
|
.params
|
|
.iter()
|
|
.map(|p| p.name.to_string())
|
|
.collect::<Vec<String>>()
|
|
.join(", ")
|
|
),
|
|
Applicability::HasPlaceholders,
|
|
);
|
|
}
|
|
}
|
|
err
|
|
}
|
|
|
|
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() {
|
|
return;
|
|
}
|
|
self.need_type_info_err(body_id, span, ty, ErrorCode::E0282)
|
|
}
|
|
|
|
ty::Predicate::Subtype(ref data) => {
|
|
if data.references_error() || self.tcx.sess.has_errors() {
|
|
// no need to overload user in such cases
|
|
return;
|
|
}
|
|
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_err(body_id, span, a, ErrorCode::E0282)
|
|
}
|
|
ty::Predicate::Projection(ref data) => {
|
|
let trait_ref = data.to_poly_trait_ref(self.tcx);
|
|
let self_ty = trait_ref.self_ty();
|
|
if predicate.references_error() {
|
|
return;
|
|
}
|
|
let mut err = self.need_type_info_err(body_id, span, self_ty, ErrorCode::E0284);
|
|
err.note(&format!("cannot resolve `{}`", predicate));
|
|
err
|
|
}
|
|
|
|
_ => {
|
|
if self.tcx.sess.has_errors() {
|
|
return;
|
|
}
|
|
let mut err = struct_span_err!(
|
|
self.tcx.sess,
|
|
span,
|
|
E0284,
|
|
"type annotations needed: cannot resolve `{}`",
|
|
predicate,
|
|
);
|
|
err.span_label(span, &format!("cannot resolve `{}`", predicate));
|
|
err
|
|
}
|
|
};
|
|
self.note_obligation_cause(&mut err, obligation);
|
|
err.emit();
|
|
}
|
|
|
|
/// Returns `true` if 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, 'tcx> {
|
|
infcx: &'a InferCtxt<'a, 'tcx>,
|
|
var_map: FxHashMap<Ty<'tcx>, Ty<'tcx>>,
|
|
}
|
|
|
|
impl<'a, 'tcx> TypeFolder<'tcx> for ParamToVarFolder<'a, 'tcx> {
|
|
fn tcx<'b>(&'b self) -> TyCtxt<'tcx> {
|
|
self.infcx.tcx
|
|
}
|
|
|
|
fn fold_ty(&mut self, ty: Ty<'tcx>) -> Ty<'tcx> {
|
|
if let ty::Param(ty::ParamTy { name, .. }) = ty.kind {
|
|
let infcx = self.infcx;
|
|
self.var_map.entry(ty).or_insert_with(|| {
|
|
infcx.next_ty_var(TypeVariableOrigin {
|
|
kind: TypeVariableOriginKind::TypeParameterDefinition(name, None),
|
|
span: DUMMY_SP,
|
|
})
|
|
})
|
|
} 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: Default::default() });
|
|
|
|
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.without_const().to_predicate(),
|
|
);
|
|
|
|
self.predicate_may_hold(&obligation)
|
|
})
|
|
}
|
|
|
|
fn note_obligation_cause(
|
|
&self,
|
|
err: &mut DiagnosticBuilder<'_>,
|
|
obligation: &PredicateObligation<'tcx>,
|
|
) {
|
|
// First, attempt to add note to this error with an async-await-specific
|
|
// message, and fall back to regular note otherwise.
|
|
if !self.maybe_note_obligation_cause_for_async_await(err, obligation) {
|
|
self.note_obligation_cause_code(
|
|
err,
|
|
&obligation.predicate,
|
|
&obligation.cause.code,
|
|
&mut vec![],
|
|
);
|
|
self.suggest_unsized_bound_if_applicable(err, obligation);
|
|
}
|
|
}
|
|
|
|
fn suggest_unsized_bound_if_applicable(
|
|
&self,
|
|
err: &mut DiagnosticBuilder<'_>,
|
|
obligation: &PredicateObligation<'tcx>,
|
|
) {
|
|
if let (
|
|
ty::Predicate::Trait(pred, _),
|
|
ObligationCauseCode::BindingObligation(item_def_id, span),
|
|
) = (&obligation.predicate, &obligation.cause.code)
|
|
{
|
|
if let (Some(generics), true) = (
|
|
self.tcx.hir().get_if_local(*item_def_id).as_ref().and_then(|n| n.generics()),
|
|
Some(pred.def_id()) == self.tcx.lang_items().sized_trait(),
|
|
) {
|
|
for param in generics.params {
|
|
if param.span == *span
|
|
&& !param.bounds.iter().any(|bound| {
|
|
bound.trait_def_id() == self.tcx.lang_items().sized_trait()
|
|
})
|
|
{
|
|
let (span, separator) = match param.bounds {
|
|
[] => (span.shrink_to_hi(), ":"),
|
|
[.., bound] => (bound.span().shrink_to_hi(), " + "),
|
|
};
|
|
err.span_suggestion(
|
|
span,
|
|
"consider relaxing the implicit `Sized` restriction",
|
|
format!("{} ?Sized", separator),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn is_recursive_obligation(
|
|
&self,
|
|
obligated_types: &mut Vec<&ty::TyS<'tcx>>,
|
|
cause_code: &ObligationCauseCode<'tcx>,
|
|
) -> bool {
|
|
if let ObligationCauseCode::BuiltinDerivedObligation(ref data) = cause_code {
|
|
let parent_trait_ref = self.resolve_vars_if_possible(&data.parent_trait_ref);
|
|
|
|
if obligated_types.iter().any(|ot| ot == &parent_trait_ref.skip_binder().self_ty()) {
|
|
return true;
|
|
}
|
|
}
|
|
false
|
|
}
|
|
}
|
|
|
|
/// Summarizes information
|
|
#[derive(Clone)]
|
|
pub enum ArgKind {
|
|
/// An argument of non-tuple type. Parameters are (name, ty)
|
|
Arg(String, String),
|
|
|
|
/// An argument of tuple type. For a "found" argument, the span is
|
|
/// the locationo in the source of the pattern. For a "expected"
|
|
/// argument, it will be None. The vector is a list of (name, ty)
|
|
/// strings for the components of the tuple.
|
|
Tuple(Option<Span>, Vec<(String, String)>),
|
|
}
|
|
|
|
impl ArgKind {
|
|
fn empty() -> ArgKind {
|
|
ArgKind::Arg("_".to_owned(), "_".to_owned())
|
|
}
|
|
|
|
/// Creates an `ArgKind` from the expected type of an
|
|
/// argument. It has no name (`_`) and an optional source span.
|
|
pub fn from_expected_ty(t: Ty<'_>, span: Option<Span>) -> ArgKind {
|
|
match t.kind {
|
|
ty::Tuple(ref tys) => ArgKind::Tuple(
|
|
span,
|
|
tys.iter().map(|ty| ("_".to_owned(), ty.to_string())).collect::<Vec<_>>(),
|
|
),
|
|
_ => ArgKind::Arg("_".to_owned(), t.to_string()),
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Suggest restricting a type param with a new bound.
|
|
pub fn suggest_constraining_type_param(
|
|
tcx: TyCtxt<'_>,
|
|
generics: &hir::Generics<'_>,
|
|
err: &mut DiagnosticBuilder<'_>,
|
|
param_name: &str,
|
|
constraint: &str,
|
|
source_map: &SourceMap,
|
|
span: Span,
|
|
def_id: Option<DefId>,
|
|
) -> bool {
|
|
const MSG_RESTRICT_BOUND_FURTHER: &str = "consider further restricting this bound with";
|
|
const MSG_RESTRICT_TYPE: &str = "consider restricting this type parameter with";
|
|
const MSG_RESTRICT_TYPE_FURTHER: &str = "consider further restricting this type parameter with";
|
|
|
|
let param = generics.params.iter().find(|p| p.name.ident().as_str() == param_name);
|
|
|
|
let param = if let Some(param) = param {
|
|
param
|
|
} else {
|
|
return false;
|
|
};
|
|
|
|
if def_id == tcx.lang_items().sized_trait() {
|
|
// Type parameters are already `Sized` by default.
|
|
err.span_label(param.span, &format!("this type parameter needs to be `{}`", constraint));
|
|
return true;
|
|
}
|
|
|
|
if param_name.starts_with("impl ") {
|
|
// If there's an `impl Trait` used in argument position, suggest
|
|
// restricting it:
|
|
//
|
|
// fn foo(t: impl Foo) { ... }
|
|
// --------
|
|
// |
|
|
// help: consider further restricting this bound with `+ Bar`
|
|
//
|
|
// Suggestion for tools in this case is:
|
|
//
|
|
// fn foo(t: impl Foo) { ... }
|
|
// --------
|
|
// |
|
|
// replace with: `impl Foo + Bar`
|
|
|
|
err.span_help(param.span, &format!("{} `+ {}`", MSG_RESTRICT_BOUND_FURTHER, constraint));
|
|
|
|
err.tool_only_span_suggestion(
|
|
param.span,
|
|
MSG_RESTRICT_BOUND_FURTHER,
|
|
format!("{} + {}", param_name, constraint),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
|
|
return true;
|
|
}
|
|
|
|
if generics.where_clause.predicates.is_empty() {
|
|
if let Some(bounds_span) = param.bounds_span() {
|
|
// If user has provided some bounds, suggest restricting them:
|
|
//
|
|
// fn foo<T: Foo>(t: T) { ... }
|
|
// ---
|
|
// |
|
|
// help: consider further restricting this bound with `+ Bar`
|
|
//
|
|
// Suggestion for tools in this case is:
|
|
//
|
|
// fn foo<T: Foo>(t: T) { ... }
|
|
// --
|
|
// |
|
|
// replace with: `T: Bar +`
|
|
|
|
err.span_help(
|
|
bounds_span,
|
|
&format!("{} `+ {}`", MSG_RESTRICT_BOUND_FURTHER, constraint),
|
|
);
|
|
|
|
let span_hi = param.span.with_hi(span.hi());
|
|
let span_with_colon = source_map.span_through_char(span_hi, ':');
|
|
|
|
if span_hi != param.span && span_with_colon != span_hi {
|
|
err.tool_only_span_suggestion(
|
|
span_with_colon,
|
|
MSG_RESTRICT_BOUND_FURTHER,
|
|
format!("{}: {} + ", param_name, constraint),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
} else {
|
|
// If user hasn't provided any bounds, suggest adding a new one:
|
|
//
|
|
// fn foo<T>(t: T) { ... }
|
|
// - help: consider restricting this type parameter with `T: Foo`
|
|
|
|
err.span_help(
|
|
param.span,
|
|
&format!("{} `{}: {}`", MSG_RESTRICT_TYPE, param_name, constraint),
|
|
);
|
|
|
|
err.tool_only_span_suggestion(
|
|
param.span,
|
|
MSG_RESTRICT_TYPE,
|
|
format!("{}: {}", param_name, constraint),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
|
|
true
|
|
} else {
|
|
// This part is a bit tricky, because using the `where` clause user can
|
|
// provide zero, one or many bounds for the same type parameter, so we
|
|
// have following cases to consider:
|
|
//
|
|
// 1) When the type parameter has been provided zero bounds
|
|
//
|
|
// Message:
|
|
// fn foo<X, Y>(x: X, y: Y) where Y: Foo { ... }
|
|
// - help: consider restricting this type parameter with `where X: Bar`
|
|
//
|
|
// Suggestion:
|
|
// fn foo<X, Y>(x: X, y: Y) where Y: Foo { ... }
|
|
// - insert: `, X: Bar`
|
|
//
|
|
//
|
|
// 2) When the type parameter has been provided one bound
|
|
//
|
|
// Message:
|
|
// fn foo<T>(t: T) where T: Foo { ... }
|
|
// ^^^^^^
|
|
// |
|
|
// help: consider further restricting this bound with `+ Bar`
|
|
//
|
|
// Suggestion:
|
|
// fn foo<T>(t: T) where T: Foo { ... }
|
|
// ^^
|
|
// |
|
|
// replace with: `T: Bar +`
|
|
//
|
|
//
|
|
// 3) When the type parameter has been provided many bounds
|
|
//
|
|
// Message:
|
|
// fn foo<T>(t: T) where T: Foo, T: Bar {... }
|
|
// - help: consider further restricting this type parameter with `where T: Zar`
|
|
//
|
|
// Suggestion:
|
|
// fn foo<T>(t: T) where T: Foo, T: Bar {... }
|
|
// - insert: `, T: Zar`
|
|
|
|
let mut param_spans = Vec::new();
|
|
|
|
for predicate in generics.where_clause.predicates {
|
|
if let WherePredicate::BoundPredicate(WhereBoundPredicate {
|
|
span, bounded_ty, ..
|
|
}) = predicate
|
|
{
|
|
if let TyKind::Path(QPath::Resolved(_, path)) = &bounded_ty.kind {
|
|
if let Some(segment) = path.segments.first() {
|
|
if segment.ident.to_string() == param_name {
|
|
param_spans.push(span);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
let where_clause_span =
|
|
generics.where_clause.span_for_predicates_or_empty_place().shrink_to_hi();
|
|
|
|
match ¶m_spans[..] {
|
|
&[] => {
|
|
err.span_help(
|
|
param.span,
|
|
&format!("{} `where {}: {}`", MSG_RESTRICT_TYPE, param_name, constraint),
|
|
);
|
|
|
|
err.tool_only_span_suggestion(
|
|
where_clause_span,
|
|
MSG_RESTRICT_TYPE,
|
|
format!(", {}: {}", param_name, constraint),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
|
|
&[¶m_span] => {
|
|
err.span_help(
|
|
param_span,
|
|
&format!("{} `+ {}`", MSG_RESTRICT_BOUND_FURTHER, constraint),
|
|
);
|
|
|
|
let span_hi = param_span.with_hi(span.hi());
|
|
let span_with_colon = source_map.span_through_char(span_hi, ':');
|
|
|
|
if span_hi != param_span && span_with_colon != span_hi {
|
|
err.tool_only_span_suggestion(
|
|
span_with_colon,
|
|
MSG_RESTRICT_BOUND_FURTHER,
|
|
format!("{}: {} +", param_name, constraint),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
}
|
|
|
|
_ => {
|
|
err.span_help(
|
|
param.span,
|
|
&format!(
|
|
"{} `where {}: {}`",
|
|
MSG_RESTRICT_TYPE_FURTHER, param_name, constraint,
|
|
),
|
|
);
|
|
|
|
err.tool_only_span_suggestion(
|
|
where_clause_span,
|
|
MSG_RESTRICT_BOUND_FURTHER,
|
|
format!(", {}: {}", param_name, constraint),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
}
|
|
|
|
true
|
|
}
|
|
}
|