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8dacfc2ada
Add `enclosing scope` parameter to `rustc_on_unimplemented` Adds a new parameter to `#[rustc_on_unimplemented]`, `enclosing scope`, which highlights the function or closure scope with a message. The wip part refers to adding this annotation to `Try` trait to improve ergonomics (which I don't know how to do since I change both std and librustc) Closes #61709.
2592 lines
109 KiB
Rust
2592 lines
109 KiB
Rust
use super::{
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ConstEvalFailure,
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EvaluationResult,
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FulfillmentError,
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FulfillmentErrorCode,
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MismatchedProjectionTypes,
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ObjectSafetyViolation,
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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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Overflow,
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PredicateObligation,
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SelectionContext,
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SelectionError,
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TraitNotObjectSafe,
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};
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use crate::hir;
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use crate::hir::Node;
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use crate::hir::def_id::DefId;
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use crate::infer::{self, InferCtxt};
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use crate::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
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use crate::session::DiagnosticMessageId;
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use crate::ty::{self, AdtKind, DefIdTree, ToPredicate, ToPolyTraitRef, Ty, TyCtxt, TypeFoldable};
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use crate::ty::GenericParamDefKind;
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use crate::ty::error::ExpectedFound;
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use crate::ty::fast_reject;
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use crate::ty::fold::TypeFolder;
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use crate::ty::subst::Subst;
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use crate::ty::SubtypePredicate;
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use crate::util::nodemap::{FxHashMap, FxHashSet};
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use errors::{Applicability, DiagnosticBuilder, pluralize, Style};
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use std::fmt;
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use syntax::ast;
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use syntax::symbol::{sym, kw};
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use syntax_pos::{DUMMY_SP, Span, ExpnKind, MultiSpan};
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use rustc::hir::def_id::LOCAL_CRATE;
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use syntax_pos::source_map::SourceMap;
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use rustc_error_codes::*;
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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<_>> =
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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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// 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(
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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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);
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self.reported_trait_errors.borrow_mut()
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.entry(span).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(
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&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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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();
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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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).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!("report_projection_error obligation.cause={:?} obligation.param_env={:?}",
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obligation.cause, obligation.param_env);
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debug!("report_projection_error normalized_ty={:?} data.ty={:?}",
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normalized_ty, data.ty);
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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)
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.eq_exp(is_normalized_ty_expected, normalized_ty, data.ty)
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{
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values = Some(infer::ValuePairs::Types(
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ExpectedFound::new(is_normalized_ty_expected, normalized_ty, data.ty)));
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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 = (
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DiagnosticMessageId::ErrorId(271),
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Some(obligation.cause.span),
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msg,
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);
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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 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, sym::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 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| {
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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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}
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/// Used to set on_unimplemented's `ItemContext`
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/// to be the enclosing (async) block/function/closure
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fn describe_enclosure(&self, hir_id: hir::HirId) -> Option<&'static str> {
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let hir = &self.tcx.hir();
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let node = hir.find(hir_id)?;
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if let hir::Node::Item(
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hir::Item{kind: hir::ItemKind::Fn(sig, _, body_id), .. }) = &node {
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self.describe_generator(*body_id).or_else(||
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Some(if let hir::FnHeader{ asyncness: hir::IsAsync::Async, .. } = sig.header {
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"an async function"
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} else {
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"a function"
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})
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)
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} else if let hir::Node::Expr(hir::Expr {
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kind: hir::ExprKind::Closure(_is_move, _, body_id, _, gen_movability), .. }) = &node {
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self.describe_generator(*body_id).or_else(||
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Some(if gen_movability.is_some() {
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"an async closure"
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} else {
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"a closure"
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})
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)
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} else if let hir::Node::Expr(hir::Expr { .. }) = &node {
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let parent_hid = hir.get_parent_node(hir_id);
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if parent_hid != hir_id {
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return self.describe_enclosure(parent_hid);
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} else {
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None
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}
|
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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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let def_id = self.impl_similar_to(trait_ref, obligation)
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.unwrap_or_else(|| trait_ref.def_id());
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let trait_ref = *trait_ref.skip_binder();
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let mut flags = vec![];
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flags.push((sym::item_context,
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self.describe_enclosure(obligation.cause.body_id).map(|s|s.to_owned())));
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|
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match obligation.cause.code {
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ObligationCauseCode::BuiltinDerivedObligation(..) |
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ObligationCauseCode::ImplDerivedObligation(..) => {}
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_ => {
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// this is a "direct", user-specified, rather than derived,
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// obligation.
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flags.push((sym::direct, None));
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}
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}
|
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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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let method = self.tcx.item_name(item);
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flags.push((sym::from_method, None));
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flags.push((sym::from_method, Some(method.to_string())));
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}
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}
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if let Some(t) = self.get_parent_trait_ref(&obligation.cause.code) {
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flags.push((sym::parent_trait, Some(t)));
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}
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|
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if let Some(k) = obligation.cause.span.desugaring_kind() {
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flags.push((sym::from_desugaring, None));
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flags.push((sym::from_desugaring, Some(format!("{:?}", k))));
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}
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let generics = self.tcx.generics_of(def_id);
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let self_ty = trait_ref.self_ty();
|
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// This is also included through the generics list as `Self`,
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// but the parser won't allow you to use it
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flags.push((sym::_Self, Some(self_ty.to_string())));
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if let Some(def) = self_ty.ty_adt_def() {
|
|
// We also want to be able to select self's original
|
|
// signature with no type arguments resolved
|
|
flags.push((sym::_Self, Some(self.tcx.type_of(def.did).to_string())));
|
|
}
|
|
|
|
for param in generics.params.iter() {
|
|
let value = match param.kind {
|
|
GenericParamDefKind::Type { .. } |
|
|
GenericParamDefKind::Const => {
|
|
trait_ref.substs[param.index as usize].to_string()
|
|
},
|
|
GenericParamDefKind::Lifetime => continue,
|
|
};
|
|
let name = param.name;
|
|
flags.push((name, Some(value)));
|
|
}
|
|
|
|
if let Some(true) = self_ty.ty_adt_def().map(|def| def.did.is_local()) {
|
|
flags.push((sym::crate_local, None));
|
|
}
|
|
|
|
// Allow targeting all integers using `{integral}`, even if the exact type was resolved
|
|
if self_ty.is_integral() {
|
|
flags.push((sym::_Self, Some("{integral}".to_owned())));
|
|
}
|
|
|
|
if let ty::Array(aty, len) = self_ty.kind {
|
|
flags.push((sym::_Self, Some("[]".to_owned())));
|
|
flags.push((sym::_Self, Some(format!("[{}]", aty))));
|
|
if let Some(def) = aty.ty_adt_def() {
|
|
// We also want to be able to select the array's type's original
|
|
// signature with no type arguments resolved
|
|
flags.push((
|
|
sym::_Self,
|
|
Some(format!("[{}]", self.tcx.type_of(def.did).to_string())),
|
|
));
|
|
let tcx = self.tcx;
|
|
if let Some(len) = len.try_eval_usize(tcx, ty::ParamEnv::empty()) {
|
|
flags.push((
|
|
sym::_Self,
|
|
Some(format!("[{}; {}]", self.tcx.type_of(def.did).to_string(), len)),
|
|
));
|
|
} else {
|
|
flags.push((
|
|
sym::_Self,
|
|
Some(format!("[{}; _]", self.tcx.type_of(def.did).to_string())),
|
|
));
|
|
}
|
|
}
|
|
}
|
|
|
|
if let Ok(Some(command)) = OnUnimplementedDirective::of_item(
|
|
self.tcx, trait_ref.def_id, def_id
|
|
) {
|
|
command.evaluate(self.tcx, trait_ref, &flags[..])
|
|
} else {
|
|
OnUnimplementedNote::default()
|
|
}
|
|
}
|
|
|
|
fn find_similar_impl_candidates(
|
|
&self,
|
|
trait_ref: ty::PolyTraitRef<'tcx>,
|
|
) -> Vec<ty::TraitRef<'tcx>> {
|
|
let simp = fast_reject::simplify_type(self.tcx, trait_ref.skip_binder().self_ty(), true);
|
|
let all_impls = self.tcx.all_impls(trait_ref.def_id());
|
|
|
|
match simp {
|
|
Some(simp) => all_impls.iter().filter_map(|&def_id| {
|
|
let imp = self.tcx.impl_trait_ref(def_id).unwrap();
|
|
let imp_simp = fast_reject::simplify_type(self.tcx, imp.self_ty(), true);
|
|
if let Some(imp_simp) = imp_simp {
|
|
if simp != imp_simp {
|
|
return None
|
|
}
|
|
}
|
|
|
|
Some(imp)
|
|
}).collect(),
|
|
None => all_impls.iter().map(|&def_id|
|
|
self.tcx.impl_trait_ref(def_id).unwrap()
|
|
).collect()
|
|
}
|
|
}
|
|
|
|
fn report_similar_impl_candidates(
|
|
&self,
|
|
impl_candidates: Vec<ty::TraitRef<'tcx>>,
|
|
err: &mut DiagnosticBuilder<'_>,
|
|
) {
|
|
if impl_candidates.is_empty() {
|
|
return;
|
|
}
|
|
|
|
let len = impl_candidates.len();
|
|
let end = if impl_candidates.len() <= 5 {
|
|
impl_candidates.len()
|
|
} else {
|
|
4
|
|
};
|
|
|
|
let normalize = |candidate| self.tcx.infer_ctxt().enter(|ref infcx| {
|
|
let normalized = infcx
|
|
.at(&ObligationCause::dummy(), ty::ParamEnv::empty())
|
|
.normalize(candidate)
|
|
.ok();
|
|
match normalized {
|
|
Some(normalized) => format!("\n {:?}", normalized.value),
|
|
None => format!("\n {:?}", candidate),
|
|
}
|
|
});
|
|
|
|
// Sort impl candidates so that ordering is consistent for UI tests.
|
|
let mut normalized_impl_candidates = impl_candidates
|
|
.iter()
|
|
.map(normalize)
|
|
.collect::<Vec<String>>();
|
|
|
|
// Sort before taking the `..end` range,
|
|
// because the ordering of `impl_candidates` may not be deterministic:
|
|
// https://github.com/rust-lang/rust/pull/57475#issuecomment-455519507
|
|
normalized_impl_candidates.sort();
|
|
|
|
err.help(&format!("the following implementations were found:{}{}",
|
|
normalized_impl_candidates[..end].join(""),
|
|
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>(
|
|
&self,
|
|
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.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: &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> {
|
|
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 => Some(parent_trait_ref.skip_binder().self_ty().to_string()),
|
|
}
|
|
}
|
|
_ => 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,
|
|
} = 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,
|
|
) = self.get_parent_trait_ref(&obligation.cause.code)
|
|
.map(|t| (format!(" in `{}`", t), format!("within `{}`, ", t)))
|
|
.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.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(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);
|
|
|
|
// 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.
|
|
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),
|
|
.. 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: https://github.com/rust-lang/rust/issues/48950 \
|
|
for more info). 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);
|
|
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.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) => {
|
|
if !self.tcx.sess.opts.debugging_opts.chalk {
|
|
// 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);
|
|
} else {
|
|
// FIXME: we'll need a better message which takes into account
|
|
// which bounds actually failed to hold.
|
|
self.tcx.sess.struct_span_err(
|
|
span,
|
|
&format!("the type `{}` is not well-formed (chalk)", 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);
|
|
self.tcx.report_object_safety_error(span, did, violations)
|
|
}
|
|
|
|
// already reported in the query
|
|
ConstEvalFailure(err) => {
|
|
self.tcx.sess.delay_span_bug(
|
|
span,
|
|
&format!("constant in type had an ignored error: {:?}", err),
|
|
);
|
|
return;
|
|
}
|
|
|
|
Overflow => {
|
|
bug!("overflow should be handled before the `report_selection_error` path");
|
|
}
|
|
};
|
|
|
|
self.note_obligation_cause(&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 suggest_restricting_param_bound(
|
|
&self,
|
|
mut err: &mut DiagnosticBuilder<'_>,
|
|
trait_ref: &ty::PolyTraitRef<'_>,
|
|
body_id: hir::HirId,
|
|
) {
|
|
let self_ty = trait_ref.self_ty();
|
|
let (param_ty, projection) = match &self_ty.kind {
|
|
ty::Param(_) => (true, None),
|
|
ty::Projection(projection) => (false, Some(projection)),
|
|
_ => return,
|
|
};
|
|
|
|
let suggest_restriction = |
|
|
generics: &hir::Generics,
|
|
msg,
|
|
err: &mut DiagnosticBuilder<'_>,
|
|
| {
|
|
let span = generics.where_clause.span_for_predicates_or_empty_place();
|
|
if !span.from_expansion() && span.desugaring_kind().is_none() {
|
|
err.span_suggestion(
|
|
generics.where_clause.span_for_predicates_or_empty_place().shrink_to_hi(),
|
|
&format!("consider further restricting {}", msg),
|
|
format!(
|
|
"{} {} ",
|
|
if !generics.where_clause.predicates.is_empty() {
|
|
","
|
|
} else {
|
|
" where"
|
|
},
|
|
trait_ref.to_predicate(),
|
|
),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
};
|
|
|
|
// FIXME: Add check for trait bound that is already present, particularly `?Sized` so we
|
|
// don't suggest `T: Sized + ?Sized`.
|
|
let mut hir_id = body_id;
|
|
while let Some(node) = self.tcx.hir().find(hir_id) {
|
|
match node {
|
|
hir::Node::TraitItem(hir::TraitItem {
|
|
generics,
|
|
kind: hir::TraitItemKind::Method(..), ..
|
|
}) if param_ty && self_ty == self.tcx.types.self_param => {
|
|
// Restricting `Self` for a single method.
|
|
suggest_restriction(&generics, "`Self`", err);
|
|
return;
|
|
}
|
|
|
|
hir::Node::Item(hir::Item {
|
|
kind: hir::ItemKind::Fn(_, generics, _), ..
|
|
}) |
|
|
hir::Node::TraitItem(hir::TraitItem {
|
|
generics,
|
|
kind: hir::TraitItemKind::Method(..), ..
|
|
}) |
|
|
hir::Node::ImplItem(hir::ImplItem {
|
|
generics,
|
|
kind: hir::ImplItemKind::Method(..), ..
|
|
}) |
|
|
hir::Node::Item(hir::Item {
|
|
kind: hir::ItemKind::Trait(_, _, generics, _, _), ..
|
|
}) |
|
|
hir::Node::Item(hir::Item {
|
|
kind: hir::ItemKind::Impl(_, _, _, generics, ..), ..
|
|
}) if projection.is_some() => {
|
|
// Missing associated type bound.
|
|
suggest_restriction(&generics, "the associated type", err);
|
|
return;
|
|
}
|
|
|
|
hir::Node::Item(hir::Item { kind: hir::ItemKind::Struct(_, generics), span, .. }) |
|
|
hir::Node::Item(hir::Item { kind: hir::ItemKind::Enum(_, generics), span, .. }) |
|
|
hir::Node::Item(hir::Item { kind: hir::ItemKind::Union(_, generics), span, .. }) |
|
|
hir::Node::Item(hir::Item {
|
|
kind: hir::ItemKind::Trait(_, _, generics, ..), span, ..
|
|
}) |
|
|
hir::Node::Item(hir::Item {
|
|
kind: hir::ItemKind::Impl(_, _, _, generics, ..), span, ..
|
|
}) |
|
|
hir::Node::Item(hir::Item {
|
|
kind: hir::ItemKind::Fn(_, generics, _), span, ..
|
|
}) |
|
|
hir::Node::Item(hir::Item {
|
|
kind: hir::ItemKind::TyAlias(_, generics), span, ..
|
|
}) |
|
|
hir::Node::Item(hir::Item {
|
|
kind: hir::ItemKind::TraitAlias(generics, _), span, ..
|
|
}) |
|
|
hir::Node::Item(hir::Item {
|
|
kind: hir::ItemKind::OpaqueTy(hir::OpaqueTy { generics, .. }), span, ..
|
|
}) |
|
|
hir::Node::TraitItem(hir::TraitItem { generics, span, .. }) |
|
|
hir::Node::ImplItem(hir::ImplItem { generics, span, .. })
|
|
if param_ty => {
|
|
// Missing generic type parameter bound.
|
|
let param_name = self_ty.to_string();
|
|
let constraint = trait_ref.print_only_trait_path().to_string();
|
|
if suggest_constraining_type_param(
|
|
generics,
|
|
&mut err,
|
|
¶m_name,
|
|
&constraint,
|
|
self.tcx.sess.source_map(),
|
|
*span,
|
|
) {
|
|
return;
|
|
}
|
|
}
|
|
|
|
hir::Node::Crate => return,
|
|
|
|
_ => {}
|
|
}
|
|
|
|
hir_id = self.tcx.hir().get_parent_item(hir_id);
|
|
}
|
|
}
|
|
|
|
/// 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(hir_id) = code {
|
|
let parent_node = self.tcx.hir().get_parent_node(hir_id);
|
|
if let Some(Node::Local(ref local)) = self.tcx.hir().find(parent_node) {
|
|
if let Some(ref expr) = local.init {
|
|
if let hir::ExprKind::Index(_, _) = expr.kind {
|
|
if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(expr.span) {
|
|
err.span_suggestion(
|
|
expr.span,
|
|
"consider borrowing here",
|
|
format!("&{}", snippet),
|
|
Applicability::MachineApplicable
|
|
);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
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.to_predicate())
|
|
}
|
|
|
|
/// Given a closure's `DefId`, return the given name of the closure.
|
|
///
|
|
/// This doesn't account for reassignments, but it's only used for suggestions.
|
|
fn get_closure_name(
|
|
&self,
|
|
def_id: DefId,
|
|
err: &mut DiagnosticBuilder<'_>,
|
|
msg: &str,
|
|
) -> Option<String> {
|
|
let get_name = |err: &mut DiagnosticBuilder<'_>, kind: &hir::PatKind| -> Option<String> {
|
|
// Get the local name of this closure. This can be inaccurate because
|
|
// of the possibility of reassignment, but this should be good enough.
|
|
match &kind {
|
|
hir::PatKind::Binding(hir::BindingAnnotation::Unannotated, _, name, None) => {
|
|
Some(format!("{}", name))
|
|
}
|
|
_ => {
|
|
err.note(&msg);
|
|
None
|
|
}
|
|
}
|
|
};
|
|
|
|
let hir = self.tcx.hir();
|
|
let hir_id = hir.as_local_hir_id(def_id)?;
|
|
let parent_node = hir.get_parent_node(hir_id);
|
|
match hir.find(parent_node) {
|
|
Some(hir::Node::Stmt(hir::Stmt {
|
|
kind: hir::StmtKind::Local(local), ..
|
|
})) => get_name(err, &local.pat.kind),
|
|
// Different to previous arm because one is `&hir::Local` and the other
|
|
// is `P<hir::Local>`.
|
|
Some(hir::Node::Local(local)) => get_name(err, &local.pat.kind),
|
|
_ => return None,
|
|
}
|
|
}
|
|
|
|
/// We tried to apply the bound to an `fn` or closure. Check whether calling it would
|
|
/// evaluate to a type that *would* satisfy the trait binding. If it would, suggest calling
|
|
/// it: `bar(foo)` → `bar(foo())`. This case is *very* likely to be hit if `foo` is `async`.
|
|
fn suggest_fn_call(
|
|
&self,
|
|
obligation: &PredicateObligation<'tcx>,
|
|
err: &mut DiagnosticBuilder<'_>,
|
|
trait_ref: &ty::Binder<ty::TraitRef<'tcx>>,
|
|
points_at_arg: bool,
|
|
) {
|
|
let self_ty = trait_ref.self_ty();
|
|
let (def_id, output_ty, callable) = match self_ty.kind {
|
|
ty::Closure(def_id, substs) => {
|
|
(def_id, self.closure_sig(def_id, substs).output(), "closure")
|
|
}
|
|
ty::FnDef(def_id, _) => {
|
|
(def_id, self_ty.fn_sig(self.tcx).output(), "function")
|
|
}
|
|
_ => return,
|
|
};
|
|
let msg = format!("use parentheses to call the {}", callable);
|
|
|
|
let obligation = self.mk_obligation_for_def_id(
|
|
trait_ref.def_id(),
|
|
output_ty.skip_binder(),
|
|
obligation.cause.clone(),
|
|
obligation.param_env,
|
|
);
|
|
|
|
match self.evaluate_obligation(&obligation) {
|
|
Ok(EvaluationResult::EvaluatedToOk) |
|
|
Ok(EvaluationResult::EvaluatedToOkModuloRegions) |
|
|
Ok(EvaluationResult::EvaluatedToAmbig) => {}
|
|
_ => return,
|
|
}
|
|
let hir = self.tcx.hir();
|
|
// Get the name of the callable and the arguments to be used in the suggestion.
|
|
let snippet = match hir.get_if_local(def_id) {
|
|
Some(hir::Node::Expr(hir::Expr {
|
|
kind: hir::ExprKind::Closure(_, decl, _, span, ..),
|
|
..
|
|
})) => {
|
|
err.span_label(*span, "consider calling this closure");
|
|
let name = match self.get_closure_name(def_id, err, &msg) {
|
|
Some(name) => name,
|
|
None => return,
|
|
};
|
|
let args = decl.inputs.iter()
|
|
.map(|_| "_")
|
|
.collect::<Vec<_>>()
|
|
.join(", ");
|
|
format!("{}({})", name, args)
|
|
}
|
|
Some(hir::Node::Item(hir::Item {
|
|
ident,
|
|
kind: hir::ItemKind::Fn(.., body_id),
|
|
..
|
|
})) => {
|
|
err.span_label(ident.span, "consider calling this function");
|
|
let body = hir.body(*body_id);
|
|
let args = body.params.iter()
|
|
.map(|arg| match &arg.pat.kind {
|
|
hir::PatKind::Binding(_, _, ident, None)
|
|
// FIXME: provide a better suggestion when encountering `SelfLower`, it
|
|
// should suggest a method call.
|
|
if ident.name != kw::SelfLower => ident.to_string(),
|
|
_ => "_".to_string(),
|
|
})
|
|
.collect::<Vec<_>>()
|
|
.join(", ");
|
|
format!("{}({})", ident, args)
|
|
}
|
|
_ => return,
|
|
};
|
|
if points_at_arg {
|
|
// When the obligation error has been ensured to have been caused by
|
|
// an argument, the `obligation.cause.span` points at the expression
|
|
// of the argument, so we can provide a suggestion. This is signaled
|
|
// by `points_at_arg`. Otherwise, we give a more general note.
|
|
err.span_suggestion(
|
|
obligation.cause.span,
|
|
&msg,
|
|
snippet,
|
|
Applicability::HasPlaceholders,
|
|
);
|
|
} else {
|
|
err.help(&format!("{}: `{}`", msg, snippet));
|
|
}
|
|
}
|
|
|
|
fn suggest_add_reference_to_arg(
|
|
&self,
|
|
obligation: &PredicateObligation<'tcx>,
|
|
err: &mut DiagnosticBuilder<'tcx>,
|
|
trait_ref: &ty::Binder<ty::TraitRef<'tcx>>,
|
|
points_at_arg: bool,
|
|
has_custom_message: bool,
|
|
) -> bool {
|
|
if !points_at_arg {
|
|
return false;
|
|
}
|
|
|
|
let span = obligation.cause.span;
|
|
let param_env = obligation.param_env;
|
|
let trait_ref = trait_ref.skip_binder();
|
|
|
|
if let ObligationCauseCode::ImplDerivedObligation(obligation) = &obligation.cause.code {
|
|
// Try to apply the original trait binding obligation by borrowing.
|
|
let self_ty = trait_ref.self_ty();
|
|
let found = self_ty.to_string();
|
|
let new_self_ty = self.tcx.mk_imm_ref(self.tcx.lifetimes.re_static, self_ty);
|
|
let substs = self.tcx.mk_substs_trait(new_self_ty, &[]);
|
|
let new_trait_ref = ty::TraitRef::new(obligation.parent_trait_ref.def_id(), substs);
|
|
let new_obligation = Obligation::new(
|
|
ObligationCause::dummy(),
|
|
param_env,
|
|
new_trait_ref.to_predicate(),
|
|
);
|
|
if self.predicate_must_hold_modulo_regions(&new_obligation) {
|
|
if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
|
|
// We have a very specific type of error, where just borrowing this argument
|
|
// might solve the problem. In cases like this, the important part is the
|
|
// original type obligation, not the last one that failed, which is arbitrary.
|
|
// Because of this, we modify the error to refer to the original obligation and
|
|
// return early in the caller.
|
|
let msg = format!(
|
|
"the trait bound `{}: {}` is not satisfied",
|
|
found,
|
|
obligation.parent_trait_ref.skip_binder().print_only_trait_path(),
|
|
);
|
|
if has_custom_message {
|
|
err.note(&msg);
|
|
} else {
|
|
err.message = vec![(msg, Style::NoStyle)];
|
|
}
|
|
if snippet.starts_with('&') {
|
|
// This is already a literal borrow and the obligation is failing
|
|
// somewhere else in the obligation chain. Do not suggest non-sense.
|
|
return false;
|
|
}
|
|
err.span_label(span, &format!(
|
|
"expected an implementor of trait `{}`",
|
|
obligation.parent_trait_ref.skip_binder().print_only_trait_path(),
|
|
));
|
|
err.span_suggestion(
|
|
span,
|
|
"consider borrowing here",
|
|
format!("&{}", snippet),
|
|
Applicability::MaybeIncorrect,
|
|
);
|
|
return true;
|
|
}
|
|
}
|
|
}
|
|
false
|
|
}
|
|
|
|
/// Whenever references are used by mistake, like `for (i, e) in &vec.iter().enumerate()`,
|
|
/// suggest removing these references until we reach a type that implements the trait.
|
|
fn suggest_remove_reference(
|
|
&self,
|
|
obligation: &PredicateObligation<'tcx>,
|
|
err: &mut DiagnosticBuilder<'tcx>,
|
|
trait_ref: &ty::Binder<ty::TraitRef<'tcx>>,
|
|
) {
|
|
let trait_ref = trait_ref.skip_binder();
|
|
let span = obligation.cause.span;
|
|
|
|
if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
|
|
let refs_number = snippet.chars()
|
|
.filter(|c| !c.is_whitespace())
|
|
.take_while(|c| *c == '&')
|
|
.count();
|
|
if let Some('\'') = snippet.chars()
|
|
.filter(|c| !c.is_whitespace())
|
|
.skip(refs_number)
|
|
.next()
|
|
{ // Do not suggest removal of borrow from type arguments.
|
|
return;
|
|
}
|
|
|
|
let mut trait_type = trait_ref.self_ty();
|
|
|
|
for refs_remaining in 0..refs_number {
|
|
if let ty::Ref(_, t_type, _) = trait_type.kind {
|
|
trait_type = t_type;
|
|
|
|
let new_obligation = self.mk_obligation_for_def_id(
|
|
trait_ref.def_id,
|
|
trait_type,
|
|
ObligationCause::dummy(),
|
|
obligation.param_env,
|
|
);
|
|
|
|
if self.predicate_may_hold(&new_obligation) {
|
|
let sp = self.tcx.sess.source_map()
|
|
.span_take_while(span, |c| c.is_whitespace() || *c == '&');
|
|
|
|
let remove_refs = refs_remaining + 1;
|
|
let format_str = format!("consider removing {} leading `&`-references",
|
|
remove_refs);
|
|
|
|
err.span_suggestion_short(
|
|
sp, &format_str, String::new(), Applicability::MachineApplicable
|
|
);
|
|
break;
|
|
}
|
|
} else {
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Check if the trait bound is implemented for a different mutability and note it in the
|
|
/// final error.
|
|
fn suggest_change_mut(
|
|
&self,
|
|
obligation: &PredicateObligation<'tcx>,
|
|
err: &mut DiagnosticBuilder<'tcx>,
|
|
trait_ref: &ty::Binder<ty::TraitRef<'tcx>>,
|
|
points_at_arg: bool,
|
|
) {
|
|
let span = obligation.cause.span;
|
|
if let Ok(snippet) = self.tcx.sess.source_map().span_to_snippet(span) {
|
|
let refs_number = snippet.chars()
|
|
.filter(|c| !c.is_whitespace())
|
|
.take_while(|c| *c == '&')
|
|
.count();
|
|
if let Some('\'') = snippet.chars()
|
|
.filter(|c| !c.is_whitespace())
|
|
.skip(refs_number)
|
|
.next()
|
|
{ // Do not suggest removal of borrow from type arguments.
|
|
return;
|
|
}
|
|
let trait_ref = self.resolve_vars_if_possible(trait_ref);
|
|
if trait_ref.has_infer_types() {
|
|
// Do not ICE while trying to find if a reborrow would succeed on a trait with
|
|
// unresolved bindings.
|
|
return;
|
|
}
|
|
|
|
if let ty::Ref(region, t_type, mutability) = trait_ref.skip_binder().self_ty().kind {
|
|
let trait_type = match mutability {
|
|
hir::Mutability::Mutable => self.tcx.mk_imm_ref(region, t_type),
|
|
hir::Mutability::Immutable => self.tcx.mk_mut_ref(region, t_type),
|
|
};
|
|
|
|
let new_obligation = self.mk_obligation_for_def_id(
|
|
trait_ref.skip_binder().def_id,
|
|
trait_type,
|
|
ObligationCause::dummy(),
|
|
obligation.param_env,
|
|
);
|
|
|
|
if self.evaluate_obligation_no_overflow(
|
|
&new_obligation,
|
|
).must_apply_modulo_regions() {
|
|
let sp = self.tcx.sess.source_map()
|
|
.span_take_while(span, |c| c.is_whitespace() || *c == '&');
|
|
if points_at_arg &&
|
|
mutability == hir::Mutability::Immutable &&
|
|
refs_number > 0
|
|
{
|
|
err.span_suggestion(
|
|
sp,
|
|
"consider changing this borrow's mutability",
|
|
"&mut ".to_string(),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
} else {
|
|
err.note(&format!(
|
|
"`{}` is implemented for `{:?}`, but not for `{:?}`",
|
|
trait_ref.print_only_trait_path(),
|
|
trait_type,
|
|
trait_ref.skip_binder().self_ty(),
|
|
));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn suggest_semicolon_removal(
|
|
&self,
|
|
obligation: &PredicateObligation<'tcx>,
|
|
err: &mut DiagnosticBuilder<'tcx>,
|
|
span: Span,
|
|
trait_ref: &ty::Binder<ty::TraitRef<'tcx>>,
|
|
) {
|
|
let hir = self.tcx.hir();
|
|
let parent_node = hir.get_parent_node(obligation.cause.body_id);
|
|
let node = hir.find(parent_node);
|
|
if let Some(hir::Node::Item(hir::Item {
|
|
kind: hir::ItemKind::Fn(sig, _, body_id),
|
|
..
|
|
})) = node {
|
|
let body = hir.body(*body_id);
|
|
if let hir::ExprKind::Block(blk, _) = &body.value.kind {
|
|
if sig.decl.output.span().overlaps(span) && blk.expr.is_none() &&
|
|
"()" == &trait_ref.self_ty().to_string()
|
|
{
|
|
// FIXME(estebank): When encountering a method with a trait
|
|
// bound not satisfied in the return type with a body that has
|
|
// no return, suggest removal of semicolon on last statement.
|
|
// Once that is added, close #54771.
|
|
if let Some(ref stmt) = blk.stmts.last() {
|
|
let sp = self.tcx.sess.source_map().end_point(stmt.span);
|
|
err.span_label(sp, "consider removing this semicolon");
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Given some node representing a fn-like thing in the HIR map,
|
|
/// returns a span and `ArgKind` information that describes the
|
|
/// arguments it expects. This can be supplied to
|
|
/// `report_arg_count_mismatch`.
|
|
pub fn get_fn_like_arguments(&self, node: Node<'_>) -> (Span, Vec<ArgKind>) {
|
|
match node {
|
|
Node::Expr(&hir::Expr {
|
|
kind: hir::ExprKind::Closure(_, ref _decl, id, span, _),
|
|
..
|
|
}) => {
|
|
(self.tcx.sess.source_map().def_span(span),
|
|
self.tcx.hir().body(id).params.iter()
|
|
.map(|arg| {
|
|
if let hir::Pat {
|
|
kind: hir::PatKind::Tuple(ref args, _),
|
|
span,
|
|
..
|
|
} = *arg.pat {
|
|
ArgKind::Tuple(
|
|
Some(span),
|
|
args.iter().map(|pat| {
|
|
let snippet = self.tcx.sess.source_map()
|
|
.span_to_snippet(pat.span).unwrap();
|
|
(snippet, "_".to_owned())
|
|
}).collect::<Vec<_>>(),
|
|
)
|
|
} else {
|
|
let name = self.tcx.sess.source_map()
|
|
.span_to_snippet(arg.pat.span).unwrap();
|
|
ArgKind::Arg(name, "_".to_owned())
|
|
}
|
|
})
|
|
.collect::<Vec<ArgKind>>())
|
|
}
|
|
Node::Item(&hir::Item {
|
|
span,
|
|
kind: hir::ItemKind::Fn(ref sig, ..),
|
|
..
|
|
}) |
|
|
Node::ImplItem(&hir::ImplItem {
|
|
span,
|
|
kind: hir::ImplItemKind::Method(ref sig, _),
|
|
..
|
|
}) |
|
|
Node::TraitItem(&hir::TraitItem {
|
|
span,
|
|
kind: hir::TraitItemKind::Method(ref sig, _),
|
|
..
|
|
}) => {
|
|
(self.tcx.sess.source_map().def_span(span), sig.decl.inputs.iter()
|
|
.map(|arg| match arg.clone().kind {
|
|
hir::TyKind::Tup(ref tys) => ArgKind::Tuple(
|
|
Some(arg.span),
|
|
vec![("_".to_owned(), "_".to_owned()); tys.len()]
|
|
),
|
|
_ => ArgKind::empty()
|
|
}).collect::<Vec<ArgKind>>())
|
|
}
|
|
Node::Ctor(ref variant_data) => {
|
|
let span = variant_data.ctor_hir_id()
|
|
.map(|hir_id| self.tcx.hir().span(hir_id))
|
|
.unwrap_or(DUMMY_SP);
|
|
let span = self.tcx.sess.source_map().def_span(span);
|
|
|
|
(span, vec![ArgKind::empty(); variant_data.fields().len()])
|
|
}
|
|
_ => panic!("non-FnLike node found: {:?}", node),
|
|
}
|
|
}
|
|
|
|
/// Reports an error when the number of arguments needed by a
|
|
/// trait match doesn't match the number that the expression
|
|
/// provides.
|
|
pub 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: &[ArgKind], other: &[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 { "" },
|
|
pluralize!(arg_length))
|
|
}
|
|
};
|
|
|
|
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));
|
|
|
|
// move |_| { ... }
|
|
// ^^^^^^^^-- def_span
|
|
//
|
|
// move |_| { ... }
|
|
// ^^^^^-- prefix
|
|
let prefix_span = self.tcx.sess.source_map().span_until_non_whitespace(found_span);
|
|
// move |_| { ... }
|
|
// ^^^-- pipe_span
|
|
let pipe_span = if let Some(span) = found_span.trim_start(prefix_span) {
|
|
span
|
|
} else {
|
|
found_span
|
|
};
|
|
|
|
// Suggest to take and ignore the arguments with expected_args_length `_`s if
|
|
// found arguments is empty (assume the user just wants to ignore args in this case).
|
|
// For example, if `expected_args_length` is 2, suggest `|_, _|`.
|
|
if found_args.is_empty() && is_closure {
|
|
let underscores = vec!["_"; expected_args.len()].join(", ");
|
|
err.span_suggestion(
|
|
pipe_span,
|
|
&format!(
|
|
"consider changing the closure to take and ignore the expected argument{}",
|
|
if expected_args.len() < 2 {
|
|
""
|
|
} else {
|
|
"s"
|
|
}
|
|
),
|
|
format!("|{}|", underscores),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
|
|
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),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
}
|
|
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 {
|
|
String::new()
|
|
},
|
|
);
|
|
err.span_suggestion(
|
|
found_span,
|
|
"change the closure to accept a tuple instead of individual arguments",
|
|
sugg,
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
}
|
|
}
|
|
|
|
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<'tcx>(tcx: TyCtxt<'tcx>, trait_ref: &ty::TraitRef<'tcx>) -> String {
|
|
let inputs = trait_ref.substs.type_at(1);
|
|
let sig = if let ty::Tuple(inputs) = inputs.kind {
|
|
tcx.mk_fn_sig(
|
|
inputs.iter().map(|k| k.expect_ty()),
|
|
tcx.mk_ty_infer(ty::TyVar(ty::TyVid { index: 0 })),
|
|
false,
|
|
hir::Unsafety::Normal,
|
|
::rustc_target::spec::abi::Abi::Rust
|
|
)
|
|
} else {
|
|
tcx.mk_fn_sig(
|
|
::std::iter::once(inputs),
|
|
tcx.mk_ty_infer(ty::TyVar(ty::TyVid { index: 0 })),
|
|
false,
|
|
hir::Unsafety::Normal,
|
|
::rustc_target::spec::abi::Abi::Rust
|
|
)
|
|
};
|
|
ty::Binder::bind(sig).to_string()
|
|
}
|
|
|
|
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<'tcx> TyCtxt<'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.source_map().def_span(span);
|
|
let mut err = struct_span_err!(self.sess, span, E0072,
|
|
"recursive type `{}` has infinite size",
|
|
self.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",
|
|
self.def_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.def_path_str(trait_def_id);
|
|
let span = self.sess.source_map().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::default();
|
|
for violation in violations {
|
|
if reported_violations.insert(violation.clone()) {
|
|
match violation.span() {
|
|
Some(span) => err.span_label(span, violation.error_msg()),
|
|
None => err.note(&violation.error_msg()),
|
|
};
|
|
}
|
|
}
|
|
|
|
if self.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;
|
|
}
|
|
|
|
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 dont 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).emit();
|
|
} else {
|
|
let mut err = struct_span_err!(
|
|
self.tcx.sess,
|
|
span,
|
|
E0283,
|
|
"type annotations needed: 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_err(body_id, span, ty).emit();
|
|
}
|
|
}
|
|
|
|
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_err(body_id,
|
|
obligation.cause.span,
|
|
a).emit();
|
|
}
|
|
}
|
|
|
|
_ => {
|
|
if !self.tcx.sess.has_errors() {
|
|
let mut err = struct_span_err!(
|
|
self.tcx.sess,
|
|
obligation.cause.span,
|
|
E0284,
|
|
"type annotations needed: cannot resolve `{}`",
|
|
predicate,
|
|
);
|
|
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),
|
|
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.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.note_obligation_cause_for_async_await(err, obligation) {
|
|
self.note_obligation_cause_code(err, &obligation.predicate, &obligation.cause.code,
|
|
&mut vec![]);
|
|
}
|
|
}
|
|
|
|
/// Adds an async-await specific note to the diagnostic:
|
|
///
|
|
/// ```ignore (diagnostic)
|
|
/// note: future does not implement `std::marker::Send` because this value is used across an
|
|
/// await
|
|
/// --> $DIR/issue-64130-non-send-future-diags.rs:15:5
|
|
/// |
|
|
/// LL | let g = x.lock().unwrap();
|
|
/// | - has type `std::sync::MutexGuard<'_, u32>`
|
|
/// LL | baz().await;
|
|
/// | ^^^^^^^^^^^ await occurs here, with `g` maybe used later
|
|
/// LL | }
|
|
/// | - `g` is later dropped here
|
|
/// ```
|
|
///
|
|
/// Returns `true` if an async-await specific note was added to the diagnostic.
|
|
fn note_obligation_cause_for_async_await(
|
|
&self,
|
|
err: &mut DiagnosticBuilder<'_>,
|
|
obligation: &PredicateObligation<'tcx>,
|
|
) -> bool {
|
|
debug!("note_obligation_cause_for_async_await: obligation.predicate={:?} \
|
|
obligation.cause.span={:?}", obligation.predicate, obligation.cause.span);
|
|
let source_map = self.tcx.sess.source_map();
|
|
|
|
// Look into the obligation predicate to determine the type in the generator which meant
|
|
// that the predicate was not satisifed.
|
|
let (trait_ref, target_ty) = match obligation.predicate {
|
|
ty::Predicate::Trait(trait_predicate) =>
|
|
(trait_predicate.skip_binder().trait_ref, trait_predicate.skip_binder().self_ty()),
|
|
_ => return false,
|
|
};
|
|
debug!("note_obligation_cause_for_async_await: target_ty={:?}", target_ty);
|
|
|
|
// Attempt to detect an async-await error by looking at the obligation causes, looking
|
|
// for only generators, generator witnesses, opaque types or `std::future::GenFuture` to
|
|
// be present.
|
|
//
|
|
// When a future does not implement a trait because of a captured type in one of the
|
|
// generators somewhere in the call stack, then the result is a chain of obligations.
|
|
// Given a `async fn` A that calls a `async fn` B which captures a non-send type and that
|
|
// future is passed as an argument to a function C which requires a `Send` type, then the
|
|
// chain looks something like this:
|
|
//
|
|
// - `BuiltinDerivedObligation` with a generator witness (B)
|
|
// - `BuiltinDerivedObligation` with a generator (B)
|
|
// - `BuiltinDerivedObligation` with `std::future::GenFuture` (B)
|
|
// - `BuiltinDerivedObligation` with `impl std::future::Future` (B)
|
|
// - `BuiltinDerivedObligation` with `impl std::future::Future` (B)
|
|
// - `BuiltinDerivedObligation` with a generator witness (A)
|
|
// - `BuiltinDerivedObligation` with a generator (A)
|
|
// - `BuiltinDerivedObligation` with `std::future::GenFuture` (A)
|
|
// - `BuiltinDerivedObligation` with `impl std::future::Future` (A)
|
|
// - `BuiltinDerivedObligation` with `impl std::future::Future` (A)
|
|
// - `BindingObligation` with `impl_send (Send requirement)
|
|
//
|
|
// The first obligations in the chain can be used to get the details of the type that is
|
|
// captured but the entire chain must be inspected to detect this case.
|
|
let mut generator = None;
|
|
let mut next_code = Some(&obligation.cause.code);
|
|
while let Some(code) = next_code {
|
|
debug!("note_obligation_cause_for_async_await: code={:?}", code);
|
|
match code {
|
|
ObligationCauseCode::BuiltinDerivedObligation(derived_obligation) |
|
|
ObligationCauseCode::ImplDerivedObligation(derived_obligation) => {
|
|
debug!("note_obligation_cause_for_async_await: self_ty.kind={:?}",
|
|
derived_obligation.parent_trait_ref.self_ty().kind);
|
|
match derived_obligation.parent_trait_ref.self_ty().kind {
|
|
ty::Adt(ty::AdtDef { did, .. }, ..) if
|
|
self.tcx.is_diagnostic_item(sym::gen_future, *did) => {},
|
|
ty::Generator(did, ..) => generator = generator.or(Some(did)),
|
|
ty::GeneratorWitness(_) | ty::Opaque(..) => {},
|
|
_ => return false,
|
|
}
|
|
|
|
next_code = Some(derived_obligation.parent_code.as_ref());
|
|
},
|
|
ObligationCauseCode::ItemObligation(_) | ObligationCauseCode::BindingObligation(..)
|
|
if generator.is_some() => break,
|
|
_ => return false,
|
|
}
|
|
}
|
|
|
|
let generator_did = generator.expect("can only reach this if there was a generator");
|
|
|
|
// Only continue to add a note if the generator is from an `async` function.
|
|
let parent_node = self.tcx.parent(generator_did)
|
|
.and_then(|parent_did| self.tcx.hir().get_if_local(parent_did));
|
|
debug!("note_obligation_cause_for_async_await: parent_node={:?}", parent_node);
|
|
if let Some(hir::Node::Item(hir::Item {
|
|
kind: hir::ItemKind::Fn(sig, _, _),
|
|
..
|
|
})) = parent_node {
|
|
debug!("note_obligation_cause_for_async_await: header={:?}", sig.header);
|
|
if sig.header.asyncness != hir::IsAsync::Async {
|
|
return false;
|
|
}
|
|
}
|
|
|
|
let span = self.tcx.def_span(generator_did);
|
|
let tables = self.tcx.typeck_tables_of(generator_did);
|
|
debug!("note_obligation_cause_for_async_await: generator_did={:?} span={:?} ",
|
|
generator_did, span);
|
|
|
|
// Look for a type inside the generator interior that matches the target type to get
|
|
// a span.
|
|
let target_span = tables.generator_interior_types.iter()
|
|
.find(|ty::GeneratorInteriorTypeCause { ty, .. }| ty::TyS::same_type(*ty, target_ty))
|
|
.map(|ty::GeneratorInteriorTypeCause { span, scope_span, .. }|
|
|
(span, source_map.span_to_snippet(*span), scope_span));
|
|
if let Some((target_span, Ok(snippet), scope_span)) = target_span {
|
|
// Look at the last interior type to get a span for the `.await`.
|
|
let await_span = tables.generator_interior_types.iter().map(|i| i.span).last().unwrap();
|
|
let mut span = MultiSpan::from_span(await_span);
|
|
span.push_span_label(
|
|
await_span, format!("await occurs here, with `{}` maybe used later", snippet));
|
|
|
|
span.push_span_label(*target_span, format!("has type `{}`", target_ty));
|
|
|
|
// If available, use the scope span to annotate the drop location.
|
|
if let Some(scope_span) = scope_span {
|
|
span.push_span_label(
|
|
source_map.end_point(*scope_span),
|
|
format!("`{}` is later dropped here", snippet),
|
|
);
|
|
}
|
|
|
|
err.span_note(span, &format!(
|
|
"future does not implement `{}` as this value is used across an await",
|
|
trait_ref.print_only_trait_path(),
|
|
));
|
|
|
|
// Add a note for the item obligation that remains - normally a note pointing to the
|
|
// bound that introduced the obligation (e.g. `T: Send`).
|
|
debug!("note_obligation_cause_for_async_await: next_code={:?}", next_code);
|
|
self.note_obligation_cause_code(
|
|
err,
|
|
&obligation.predicate,
|
|
next_code.unwrap(),
|
|
&mut Vec::new(),
|
|
);
|
|
|
|
true
|
|
} else {
|
|
false
|
|
}
|
|
}
|
|
|
|
fn note_obligation_cause_code<T>(&self,
|
|
err: &mut DiagnosticBuilder<'_>,
|
|
predicate: &T,
|
|
cause_code: &ObligationCauseCode<'tcx>,
|
|
obligated_types: &mut Vec<&ty::TyS<'tcx>>)
|
|
where T: fmt::Display
|
|
{
|
|
let tcx = self.tcx;
|
|
match *cause_code {
|
|
ObligationCauseCode::ExprAssignable |
|
|
ObligationCauseCode::MatchExpressionArm { .. } |
|
|
ObligationCauseCode::MatchExpressionArmPattern { .. } |
|
|
ObligationCauseCode::IfExpression { .. } |
|
|
ObligationCauseCode::IfExpressionWithNoElse |
|
|
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.def_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.source_map().def_span(sp);
|
|
err.span_label(sp, &msg);
|
|
} else {
|
|
err.note(&msg);
|
|
}
|
|
}
|
|
ObligationCauseCode::BindingObligation(item_def_id, span) => {
|
|
let item_name = tcx.def_path_str(item_def_id);
|
|
let msg = format!("required by this bound in `{}`", item_name);
|
|
if let Some(ident) = tcx.opt_item_name(item_def_id) {
|
|
err.span_label(ident.span, "");
|
|
}
|
|
if span != DUMMY_SP {
|
|
err.span_label(span, &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::Coercion { source: _, target } => {
|
|
err.note(&format!("required by cast to type `{}`",
|
|
self.ty_to_string(target)));
|
|
}
|
|
ObligationCauseCode::RepeatVec(suggest_const_in_array_repeat_expressions) => {
|
|
err.note("the `Copy` trait is required because the \
|
|
repeated element will be copied");
|
|
if suggest_const_in_array_repeat_expressions {
|
|
err.note("this array initializer can be evaluated at compile-time, for more \
|
|
information, see issue \
|
|
https://github.com/rust-lang/rust/issues/49147");
|
|
if tcx.sess.opts.unstable_features.is_nightly_build() {
|
|
err.help("add `#![feature(const_in_array_repeat_expressions)]` to the \
|
|
crate attributes to enable");
|
|
}
|
|
}
|
|
}
|
|
ObligationCauseCode::VariableType(_) => {
|
|
err.note("all local variables must have a statically known size");
|
|
if !self.tcx.features().unsized_locals {
|
|
err.help("unsized locals are gated as an unstable feature");
|
|
}
|
|
}
|
|
ObligationCauseCode::SizedArgumentType => {
|
|
err.note("all function arguments must have a statically known size");
|
|
if !self.tcx.features().unsized_locals {
|
|
err.help("unsized locals are gated as an unstable feature");
|
|
}
|
|
}
|
|
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 { adt_kind: ref item, last } => {
|
|
match *item {
|
|
AdtKind::Struct => {
|
|
if last {
|
|
err.note("the last field of a packed struct may only have a \
|
|
dynamically sized type if it does not need drop to be run");
|
|
} else {
|
|
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::ConstPatternStructural => {
|
|
err.note("constants used for pattern-matching must derive `PartialEq` and `Eq`");
|
|
}
|
|
ObligationCauseCode::SharedStatic => {
|
|
err.note("shared static variables must have a type that implements `Sync`");
|
|
}
|
|
ObligationCauseCode::BuiltinDerivedObligation(ref data) => {
|
|
let parent_trait_ref = self.resolve_vars_if_possible(&data.parent_trait_ref);
|
|
let ty = parent_trait_ref.skip_binder().self_ty();
|
|
err.note(&format!("required because it appears within the type `{}`", ty));
|
|
obligated_types.push(ty);
|
|
|
|
let parent_predicate = parent_trait_ref.to_predicate();
|
|
if !self.is_recursive_obligation(obligated_types, &data.parent_code) {
|
|
self.note_obligation_cause_code(err,
|
|
&parent_predicate,
|
|
&data.parent_code,
|
|
obligated_types);
|
|
}
|
|
}
|
|
ObligationCauseCode::ImplDerivedObligation(ref data) => {
|
|
let parent_trait_ref = self.resolve_vars_if_possible(&data.parent_trait_ref);
|
|
err.note(
|
|
&format!("required because of the requirements on the impl of `{}` for `{}`",
|
|
parent_trait_ref.print_only_trait_path(),
|
|
parent_trait_ref.skip_binder().self_ty()));
|
|
let parent_predicate = parent_trait_ref.to_predicate();
|
|
self.note_obligation_cause_code(err,
|
|
&parent_predicate,
|
|
&data.parent_code,
|
|
obligated_types);
|
|
}
|
|
ObligationCauseCode::CompareImplMethodObligation { .. } => {
|
|
err.note(
|
|
&format!("the requirement `{}` appears on the impl method \
|
|
but not on the corresponding trait method",
|
|
predicate));
|
|
}
|
|
ObligationCauseCode::ReturnType |
|
|
ObligationCauseCode::ReturnValue(_) |
|
|
ObligationCauseCode::BlockTailExpression(_) => (),
|
|
ObligationCauseCode::TrivialBound => {
|
|
err.help("see issue #48214");
|
|
if tcx.sess.opts.unstable_features.is_nightly_build() {
|
|
err.help("add `#![feature(trivial_bounds)]` to the \
|
|
crate attributes to enable",
|
|
);
|
|
}
|
|
}
|
|
ObligationCauseCode::AssocTypeBound(ref data) => {
|
|
err.span_label(data.original, "associated type defined here");
|
|
if let Some(sp) = data.impl_span {
|
|
err.span_label(sp, "in this `impl` item");
|
|
}
|
|
for sp in &data.bounds {
|
|
err.span_label(*sp, "restricted in this bound");
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
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));
|
|
}
|
|
|
|
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(
|
|
generics: &hir::Generics,
|
|
err: &mut DiagnosticBuilder<'_>,
|
|
param_name: &str,
|
|
constraint: &str,
|
|
source_map: &SourceMap,
|
|
span: Span,
|
|
) -> bool {
|
|
let restrict_msg = "consider further restricting this bound";
|
|
if let Some(param) = generics.params.iter().filter(|p| {
|
|
p.name.ident().as_str() == param_name
|
|
}).next() {
|
|
if param_name.starts_with("impl ") {
|
|
// `impl Trait` in argument:
|
|
// `fn foo(x: impl Trait) {}` → `fn foo(t: impl Trait + Trait2) {}`
|
|
err.span_suggestion(
|
|
param.span,
|
|
restrict_msg,
|
|
// `impl CurrentTrait + MissingTrait`
|
|
format!("{} + {}", param_name, constraint),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
} else if generics.where_clause.predicates.is_empty() &&
|
|
param.bounds.is_empty()
|
|
{
|
|
// If there are no bounds whatsoever, suggest adding a constraint
|
|
// to the type parameter:
|
|
// `fn foo<T>(t: T) {}` → `fn foo<T: Trait>(t: T) {}`
|
|
err.span_suggestion(
|
|
param.span,
|
|
"consider restricting this bound",
|
|
format!("{}: {}", param_name, constraint),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
} else if !generics.where_clause.predicates.is_empty() {
|
|
// There is a `where` clause, so suggest expanding it:
|
|
// `fn foo<T>(t: T) where T: Debug {}` →
|
|
// `fn foo<T>(t: T) where T: Debug, T: Trait {}`
|
|
err.span_suggestion(
|
|
generics.where_clause.span().unwrap().shrink_to_hi(),
|
|
&format!("consider further restricting type parameter `{}`", param_name),
|
|
format!(", {}: {}", param_name, constraint),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
} else {
|
|
// If there is no `where` clause lean towards constraining to the
|
|
// type parameter:
|
|
// `fn foo<X: Bar, T>(t: T, x: X) {}` → `fn foo<T: Trait>(t: T) {}`
|
|
// `fn foo<T: Bar>(t: T) {}` → `fn foo<T: Bar + Trait>(t: T) {}`
|
|
let sp = param.span.with_hi(span.hi());
|
|
let span = source_map.span_through_char(sp, ':');
|
|
if sp != param.span && sp != span {
|
|
// Only suggest if we have high certainty that the span
|
|
// covers the colon in `foo<T: Trait>`.
|
|
err.span_suggestion(
|
|
span,
|
|
restrict_msg,
|
|
format!("{}: {} + ", param_name, constraint),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
} else {
|
|
err.span_label(
|
|
param.span,
|
|
&format!("consider adding a `where {}: {}` bound", param_name, constraint),
|
|
);
|
|
}
|
|
}
|
|
return true;
|
|
}
|
|
false
|
|
}
|