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error_reporting.rs
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error_reporting.rs
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// Copyright 2012-2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//! Error Reporting Code for the inference engine
//!
//! Because of the way inference, and in particular region inference,
//! works, it often happens that errors are not detected until far after
//! the relevant line of code has been type-checked. Therefore, there is
//! an elaborate system to track why a particular constraint in the
//! inference graph arose so that we can explain to the user what gave
//! rise to a particular error.
//!
//! The basis of the system are the "origin" types. An "origin" is the
//! reason that a constraint or inference variable arose. There are
//! different "origin" enums for different kinds of constraints/variables
//! (e.g., `TypeOrigin`, `RegionVariableOrigin`). An origin always has
//! a span, but also more information so that we can generate a meaningful
//! error message.
//!
//! Having a catalogue of all the different reasons an error can arise is
//! also useful for other reasons, like cross-referencing FAQs etc, though
//! we are not really taking advantage of this yet.
//!
//! # Region Inference
//!
//! Region inference is particularly tricky because it always succeeds "in
//! the moment" and simply registers a constraint. Then, at the end, we
//! can compute the full graph and report errors, so we need to be able to
//! store and later report what gave rise to the conflicting constraints.
//!
//! # Subtype Trace
//!
//! Determining whether `T1 <: T2` often involves a number of subtypes and
//! subconstraints along the way. A "TypeTrace" is an extended version
//! of an origin that traces the types and other values that were being
//! compared. It is not necessarily comprehensive (in fact, at the time of
//! this writing it only tracks the root values being compared) but I'd
//! like to extend it to include significant "waypoints". For example, if
//! you are comparing `(T1, T2) <: (T3, T4)`, and the problem is that `T2
//! <: T4` fails, I'd like the trace to include enough information to say
//! "in the 2nd element of the tuple". Similarly, failures when comparing
//! arguments or return types in fn types should be able to cite the
//! specific position, etc.
//!
//! # Reality vs plan
//!
//! Of course, there is still a LOT of code in typeck that has yet to be
//! ported to this system, and which relies on string concatenation at the
//! time of error detection.
use self::FreshOrKept::*;
use super::InferCtxt;
use super::TypeTrace;
use super::SubregionOrigin;
use super::RegionVariableOrigin;
use super::ValuePairs;
use super::region_inference::RegionResolutionError;
use super::region_inference::ConcreteFailure;
use super::region_inference::SubSupConflict;
use super::region_inference::GenericBoundFailure;
use super::region_inference::GenericKind;
use super::region_inference::ProcessedErrors;
use super::region_inference::ProcessedErrorOrigin;
use super::region_inference::SameRegions;
use std::collections::HashSet;
use hir::map as ast_map;
use hir;
use lint;
use hir::def::Def;
use hir::def_id::DefId;
use infer;
use middle::region;
use traits::{ObligationCause, ObligationCauseCode};
use ty::{self, TyCtxt, TypeFoldable};
use ty::{Region, ReFree};
use ty::error::TypeError;
use std::cell::{Cell, RefCell};
use std::char::from_u32;
use std::fmt;
use syntax::ast;
use syntax::ptr::P;
use syntax::symbol::Symbol;
use syntax_pos::{self, Pos, Span};
use errors::DiagnosticBuilder;
impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
pub fn note_and_explain_region(self,
err: &mut DiagnosticBuilder,
prefix: &str,
region: &'tcx ty::Region,
suffix: &str) {
fn item_scope_tag(item: &hir::Item) -> &'static str {
match item.node {
hir::ItemImpl(..) => "impl",
hir::ItemStruct(..) => "struct",
hir::ItemUnion(..) => "union",
hir::ItemEnum(..) => "enum",
hir::ItemTrait(..) => "trait",
hir::ItemFn(..) => "function body",
_ => "item"
}
}
fn trait_item_scope_tag(item: &hir::TraitItem) -> &'static str {
match item.node {
hir::TraitItemKind::Method(..) => "method body",
hir::TraitItemKind::Const(..) |
hir::TraitItemKind::Type(..) => "associated item"
}
}
fn impl_item_scope_tag(item: &hir::ImplItem) -> &'static str {
match item.node {
hir::ImplItemKind::Method(..) => "method body",
hir::ImplItemKind::Const(..) |
hir::ImplItemKind::Type(_) => "associated item"
}
}
fn explain_span<'a, 'gcx, 'tcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>,
heading: &str, span: Span)
-> (String, Option<Span>) {
let lo = tcx.sess.codemap().lookup_char_pos_adj(span.lo);
(format!("the {} at {}:{}", heading, lo.line, lo.col.to_usize()),
Some(span))
}
let (description, span) = match *region {
ty::ReScope(scope) => {
let new_string;
let unknown_scope = || {
format!("{}unknown scope: {:?}{}. Please report a bug.",
prefix, scope, suffix)
};
let span = match scope.span(&self.region_maps, &self.map) {
Some(s) => s,
None => {
err.note(&unknown_scope());
return;
}
};
let tag = match self.map.find(scope.node_id(&self.region_maps)) {
Some(ast_map::NodeBlock(_)) => "block",
Some(ast_map::NodeExpr(expr)) => match expr.node {
hir::ExprCall(..) => "call",
hir::ExprMethodCall(..) => "method call",
hir::ExprMatch(.., hir::MatchSource::IfLetDesugar { .. }) => "if let",
hir::ExprMatch(.., hir::MatchSource::WhileLetDesugar) => "while let",
hir::ExprMatch(.., hir::MatchSource::ForLoopDesugar) => "for",
hir::ExprMatch(..) => "match",
_ => "expression",
},
Some(ast_map::NodeStmt(_)) => "statement",
Some(ast_map::NodeItem(it)) => item_scope_tag(&it),
Some(ast_map::NodeTraitItem(it)) => trait_item_scope_tag(&it),
Some(ast_map::NodeImplItem(it)) => impl_item_scope_tag(&it),
Some(_) | None => {
err.span_note(span, &unknown_scope());
return;
}
};
let scope_decorated_tag = match self.region_maps.code_extent_data(scope) {
region::CodeExtentData::Misc(_) => tag,
region::CodeExtentData::CallSiteScope { .. } => {
"scope of call-site for function"
}
region::CodeExtentData::ParameterScope { .. } => {
"scope of function body"
}
region::CodeExtentData::DestructionScope(_) => {
new_string = format!("destruction scope surrounding {}", tag);
&new_string[..]
}
region::CodeExtentData::Remainder(r) => {
new_string = format!("block suffix following statement {}",
r.first_statement_index);
&new_string[..]
}
};
explain_span(self, scope_decorated_tag, span)
}
ty::ReFree(ref fr) => {
let prefix = match fr.bound_region {
ty::BrAnon(idx) => {
format!("the anonymous lifetime #{} defined on", idx + 1)
}
ty::BrFresh(_) => "an anonymous lifetime defined on".to_owned(),
_ => {
format!("the lifetime {} as defined on",
fr.bound_region)
}
};
let node = fr.scope.node_id(&self.region_maps);
let unknown;
let tag = match self.map.find(node) {
Some(ast_map::NodeBlock(_)) |
Some(ast_map::NodeExpr(_)) => "body",
Some(ast_map::NodeItem(it)) => item_scope_tag(&it),
Some(ast_map::NodeTraitItem(it)) => trait_item_scope_tag(&it),
Some(ast_map::NodeImplItem(it)) => impl_item_scope_tag(&it),
// this really should not happen, but it does:
// FIXME(#27942)
Some(_) => {
unknown = format!("unexpected node ({}) for scope {:?}. \
Please report a bug.",
self.map.node_to_string(node), fr.scope);
&unknown
}
None => {
unknown = format!("unknown node for scope {:?}. \
Please report a bug.", fr.scope);
&unknown
}
};
let (msg, opt_span) = explain_span(self, tag, self.map.span(node));
(format!("{} {}", prefix, msg), opt_span)
}
ty::ReStatic => ("the static lifetime".to_owned(), None),
ty::ReEmpty => ("the empty lifetime".to_owned(), None),
ty::ReEarlyBound(ref data) => (data.name.to_string(), None),
// FIXME(#13998) ReSkolemized should probably print like
// ReFree rather than dumping Debug output on the user.
//
// We shouldn't really be having unification failures with ReVar
// and ReLateBound though.
ty::ReSkolemized(..) |
ty::ReVar(_) |
ty::ReLateBound(..) |
ty::ReErased => {
(format!("lifetime {:?}", region), None)
}
};
let message = format!("{}{}{}", prefix, description, suffix);
if let Some(span) = span {
err.span_note(span, &message);
} else {
err.note(&message);
}
}
}
impl<'a, 'gcx, 'tcx> InferCtxt<'a, 'gcx, 'tcx> {
pub fn report_region_errors(&self,
errors: &Vec<RegionResolutionError<'tcx>>) {
debug!("report_region_errors(): {} errors to start", errors.len());
// try to pre-process the errors, which will group some of them
// together into a `ProcessedErrors` group:
let processed_errors = self.process_errors(errors);
let errors = processed_errors.as_ref().unwrap_or(errors);
debug!("report_region_errors: {} errors after preprocessing", errors.len());
for error in errors {
debug!("report_region_errors: error = {:?}", error);
match error.clone() {
ConcreteFailure(origin, sub, sup) => {
self.report_concrete_failure(origin, sub, sup).emit();
}
GenericBoundFailure(kind, param_ty, sub) => {
self.report_generic_bound_failure(kind, param_ty, sub);
}
SubSupConflict(var_origin,
sub_origin, sub_r,
sup_origin, sup_r) => {
self.report_sub_sup_conflict(var_origin,
sub_origin, sub_r,
sup_origin, sup_r);
}
ProcessedErrors(ref origins,
ref same_regions) => {
if !same_regions.is_empty() {
self.report_processed_errors(origins, same_regions);
}
}
}
}
}
// This method goes through all the errors and try to group certain types
// of error together, for the purpose of suggesting explicit lifetime
// parameters to the user. This is done so that we can have a more
// complete view of what lifetimes should be the same.
// If the return value is an empty vector, it means that processing
// failed (so the return value of this method should not be used).
//
// The method also attempts to weed out messages that seem like
// duplicates that will be unhelpful to the end-user. But
// obviously it never weeds out ALL errors.
fn process_errors(&self, errors: &Vec<RegionResolutionError<'tcx>>)
-> Option<Vec<RegionResolutionError<'tcx>>> {
debug!("process_errors()");
let mut origins = Vec::new();
// we collect up ConcreteFailures and SubSupConflicts that are
// relating free-regions bound on the fn-header and group them
// together into this vector
let mut same_regions = Vec::new();
// here we put errors that we will not be able to process nicely
let mut other_errors = Vec::new();
// we collect up GenericBoundFailures in here.
let mut bound_failures = Vec::new();
for error in errors {
// Check whether we can process this error into some other
// form; if not, fall through.
match *error {
ConcreteFailure(ref origin, sub, sup) => {
debug!("processing ConcreteFailure");
if let SubregionOrigin::CompareImplMethodObligation { .. } = *origin {
// When comparing an impl method against a
// trait method, it is not helpful to suggest
// changes to the impl method. This is
// because the impl method signature is being
// checked using the trait's environment, so
// usually the changes we suggest would
// actually have to be applied to the *trait*
// method (and it's not clear that the trait
// method is even under the user's control).
} else if let Some(same_frs) = free_regions_from_same_fn(self.tcx, sub, sup) {
origins.push(
ProcessedErrorOrigin::ConcreteFailure(
origin.clone(),
sub,
sup));
append_to_same_regions(&mut same_regions, &same_frs);
continue;
}
}
SubSupConflict(ref var_origin, ref sub_origin, sub, ref sup_origin, sup) => {
debug!("processing SubSupConflict sub: {:?} sup: {:?}", sub, sup);
match (sub_origin, sup_origin) {
(&SubregionOrigin::CompareImplMethodObligation { .. }, _) => {
// As above, when comparing an impl method
// against a trait method, it is not helpful
// to suggest changes to the impl method.
}
(_, &SubregionOrigin::CompareImplMethodObligation { .. }) => {
// See above.
}
_ => {
if let Some(same_frs) = free_regions_from_same_fn(self.tcx, sub, sup) {
origins.push(
ProcessedErrorOrigin::VariableFailure(
var_origin.clone()));
append_to_same_regions(&mut same_regions, &same_frs);
continue;
}
}
}
}
GenericBoundFailure(ref origin, ref kind, region) => {
bound_failures.push((origin.clone(), kind.clone(), region));
continue;
}
ProcessedErrors(..) => {
bug!("should not encounter a `ProcessedErrors` yet: {:?}", error)
}
}
// No changes to this error.
other_errors.push(error.clone());
}
// ok, let's pull together the errors, sorted in an order that
// we think will help user the best
let mut processed_errors = vec![];
// first, put the processed errors, if any
if !same_regions.is_empty() {
let common_scope_id = same_regions[0].scope_id;
for sr in &same_regions {
// Since ProcessedErrors is used to reconstruct the function
// declaration, we want to make sure that they are, in fact,
// from the same scope
if sr.scope_id != common_scope_id {
debug!("returning empty result from process_errors because
{} != {}", sr.scope_id, common_scope_id);
return None;
}
}
assert!(origins.len() > 0);
let pe = ProcessedErrors(origins, same_regions);
debug!("errors processed: {:?}", pe);
processed_errors.push(pe);
}
// next, put the other misc errors
processed_errors.extend(other_errors);
// finally, put the `T: 'a` errors, but only if there were no
// other errors. otherwise, these have a very high rate of
// being unhelpful in practice. This is because they are
// basically secondary checks that test the state of the
// region graph after the rest of inference is done, and the
// other kinds of errors indicate that the region constraint
// graph is internally inconsistent, so these test results are
// likely to be meaningless.
if processed_errors.is_empty() {
for (origin, kind, region) in bound_failures {
processed_errors.push(GenericBoundFailure(origin, kind, region));
}
}
// we should always wind up with SOME errors, unless there were no
// errors to start
assert!(if errors.len() > 0 {processed_errors.len() > 0} else {true});
return Some(processed_errors);
#[derive(Debug)]
struct FreeRegionsFromSameFn {
sub_fr: ty::FreeRegion,
sup_fr: ty::FreeRegion,
scope_id: ast::NodeId
}
impl FreeRegionsFromSameFn {
fn new(sub_fr: ty::FreeRegion,
sup_fr: ty::FreeRegion,
scope_id: ast::NodeId)
-> FreeRegionsFromSameFn {
FreeRegionsFromSameFn {
sub_fr: sub_fr,
sup_fr: sup_fr,
scope_id: scope_id
}
}
}
fn free_regions_from_same_fn<'a, 'gcx, 'tcx>(tcx: TyCtxt<'a, 'gcx, 'tcx>,
sub: &'tcx Region,
sup: &'tcx Region)
-> Option<FreeRegionsFromSameFn> {
debug!("free_regions_from_same_fn(sub={:?}, sup={:?})", sub, sup);
let (scope_id, fr1, fr2) = match (sub, sup) {
(&ReFree(fr1), &ReFree(fr2)) => {
if fr1.scope != fr2.scope {
return None
}
assert!(fr1.scope == fr2.scope);
(fr1.scope.node_id(&tcx.region_maps), fr1, fr2)
},
_ => return None
};
let parent = tcx.map.get_parent(scope_id);
let parent_node = tcx.map.find(parent);
match parent_node {
Some(node) => match node {
ast_map::NodeItem(item) => match item.node {
hir::ItemFn(..) => {
Some(FreeRegionsFromSameFn::new(fr1, fr2, scope_id))
},
_ => None
},
ast_map::NodeImplItem(..) |
ast_map::NodeTraitItem(..) => {
Some(FreeRegionsFromSameFn::new(fr1, fr2, scope_id))
},
_ => None
},
None => {
debug!("no parent node of scope_id {}", scope_id);
None
}
}
}
fn append_to_same_regions(same_regions: &mut Vec<SameRegions>,
same_frs: &FreeRegionsFromSameFn) {
debug!("append_to_same_regions(same_regions={:?}, same_frs={:?})",
same_regions, same_frs);
let scope_id = same_frs.scope_id;
let (sub_fr, sup_fr) = (same_frs.sub_fr, same_frs.sup_fr);
for sr in same_regions.iter_mut() {
if sr.contains(&sup_fr.bound_region) && scope_id == sr.scope_id {
sr.push(sub_fr.bound_region);
return
}
}
same_regions.push(SameRegions {
scope_id: scope_id,
regions: vec![sub_fr.bound_region, sup_fr.bound_region]
})
}
}
/// Adds a note if the types come from similarly named crates
fn check_and_note_conflicting_crates(&self,
err: &mut DiagnosticBuilder,
terr: &TypeError<'tcx>,
sp: Span) {
let report_path_match = |err: &mut DiagnosticBuilder, did1: DefId, did2: DefId| {
// Only external crates, if either is from a local
// module we could have false positives
if !(did1.is_local() || did2.is_local()) && did1.krate != did2.krate {
let exp_path = self.tcx.item_path_str(did1);
let found_path = self.tcx.item_path_str(did2);
// We compare strings because DefPath can be different
// for imported and non-imported crates
if exp_path == found_path {
let crate_name = self.tcx.sess.cstore.crate_name(did1.krate);
err.span_note(sp, &format!("Perhaps two different versions \
of crate `{}` are being used?",
crate_name));
}
}
};
match *terr {
TypeError::Sorts(ref exp_found) => {
// if they are both "path types", there's a chance of ambiguity
// due to different versions of the same crate
match (&exp_found.expected.sty, &exp_found.found.sty) {
(&ty::TyAdt(exp_adt, _), &ty::TyAdt(found_adt, _)) => {
report_path_match(err, exp_adt.did, found_adt.did);
},
_ => ()
}
},
TypeError::Traits(ref exp_found) => {
report_path_match(err, exp_found.expected, exp_found.found);
},
_ => () // FIXME(#22750) handle traits and stuff
}
}
fn note_error_origin(&self,
err: &mut DiagnosticBuilder<'tcx>,
cause: &ObligationCause<'tcx>)
{
match cause.code {
ObligationCauseCode::MatchExpressionArm { arm_span, source } => match source {
hir::MatchSource::IfLetDesugar {..} => {
err.span_note(arm_span, "`if let` arm with an incompatible type");
}
_ => {
err.span_note(arm_span, "match arm with an incompatible type");
}
},
_ => ()
}
}
pub fn note_type_err(&self,
diag: &mut DiagnosticBuilder<'tcx>,
cause: &ObligationCause<'tcx>,
secondary_span: Option<(Span, String)>,
values: Option<ValuePairs<'tcx>>,
terr: &TypeError<'tcx>)
{
let expected_found = match values {
None => None,
Some(values) => match self.values_str(&values) {
Some((expected, found)) => Some((expected, found)),
None => {
// Derived error. Cancel the emitter.
self.tcx.sess.diagnostic().cancel(diag);
return
}
}
};
let span = cause.span;
if let Some((expected, found)) = expected_found {
let is_simple_error = if let &TypeError::Sorts(ref values) = terr {
values.expected.is_primitive() && values.found.is_primitive()
} else {
false
};
if !is_simple_error {
if expected == found {
if let &TypeError::Sorts(ref values) = terr {
diag.note_expected_found_extra(
&"type", &expected, &found,
&format!(" ({})", values.expected.sort_string(self.tcx)),
&format!(" ({})", values.found.sort_string(self.tcx)));
} else {
diag.note_expected_found(&"type", &expected, &found);
}
} else {
diag.note_expected_found(&"type", &expected, &found);
}
}
}
diag.span_label(span, &terr);
if let Some((sp, msg)) = secondary_span {
diag.span_label(sp, &msg);
}
self.note_error_origin(diag, &cause);
self.check_and_note_conflicting_crates(diag, terr, span);
self.tcx.note_and_explain_type_err(diag, terr, span);
}
pub fn report_and_explain_type_error(&self,
trace: TypeTrace<'tcx>,
terr: &TypeError<'tcx>)
-> DiagnosticBuilder<'tcx>
{
let span = trace.cause.span;
let failure_str = trace.cause.as_failure_str();
let mut diag = match trace.cause.code {
ObligationCauseCode::IfExpressionWithNoElse => {
struct_span_err!(self.tcx.sess, span, E0317, "{}", failure_str)
},
_ => {
struct_span_err!(self.tcx.sess, span, E0308, "{}", failure_str)
},
};
self.note_type_err(&mut diag, &trace.cause, None, Some(trace.values), terr);
diag
}
/// Returns a string of the form "expected `{}`, found `{}`".
fn values_str(&self, values: &ValuePairs<'tcx>) -> Option<(String, String)> {
match *values {
infer::Types(ref exp_found) => self.expected_found_str(exp_found),
infer::TraitRefs(ref exp_found) => self.expected_found_str(exp_found),
infer::PolyTraitRefs(ref exp_found) => self.expected_found_str(exp_found),
}
}
fn expected_found_str<T: fmt::Display + TypeFoldable<'tcx>>(
&self,
exp_found: &ty::error::ExpectedFound<T>)
-> Option<(String, String)>
{
let exp_found = self.resolve_type_vars_if_possible(exp_found);
if exp_found.references_error() {
return None;
}
Some((format!("{}", exp_found.expected), format!("{}", exp_found.found)))
}
fn report_generic_bound_failure(&self,
origin: SubregionOrigin<'tcx>,
bound_kind: GenericKind<'tcx>,
sub: &'tcx Region)
{
// FIXME: it would be better to report the first error message
// with the span of the parameter itself, rather than the span
// where the error was detected. But that span is not readily
// accessible.
let labeled_user_string = match bound_kind {
GenericKind::Param(ref p) =>
format!("the parameter type `{}`", p),
GenericKind::Projection(ref p) =>
format!("the associated type `{}`", p),
};
if let SubregionOrigin::CompareImplMethodObligation {
span, item_name, impl_item_def_id, trait_item_def_id, lint_id
} = origin {
self.report_extra_impl_obligation(span,
item_name,
impl_item_def_id,
trait_item_def_id,
&format!("`{}: {}`", bound_kind, sub),
lint_id)
.emit();
return;
}
let mut err = match *sub {
ty::ReFree(ty::FreeRegion {bound_region: ty::BrNamed(..), ..}) => {
// Does the required lifetime have a nice name we can print?
let mut err = struct_span_err!(self.tcx.sess,
origin.span(),
E0309,
"{} may not live long enough",
labeled_user_string);
err.help(&format!("consider adding an explicit lifetime bound `{}: {}`...",
bound_kind,
sub));
err
}
ty::ReStatic => {
// Does the required lifetime have a nice name we can print?
let mut err = struct_span_err!(self.tcx.sess,
origin.span(),
E0310,
"{} may not live long enough",
labeled_user_string);
err.help(&format!("consider adding an explicit lifetime \
bound `{}: 'static`...",
bound_kind));
err
}
_ => {
// If not, be less specific.
let mut err = struct_span_err!(self.tcx.sess,
origin.span(),
E0311,
"{} may not live long enough",
labeled_user_string);
err.help(&format!("consider adding an explicit lifetime bound for `{}`",
bound_kind));
self.tcx.note_and_explain_region(
&mut err,
&format!("{} must be valid for ", labeled_user_string),
sub,
"...");
err
}
};
self.note_region_origin(&mut err, &origin);
err.emit();
}
fn report_concrete_failure(&self,
origin: SubregionOrigin<'tcx>,
sub: &'tcx Region,
sup: &'tcx Region)
-> DiagnosticBuilder<'tcx> {
match origin {
infer::Subtype(trace) => {
let terr = TypeError::RegionsDoesNotOutlive(sup, sub);
self.report_and_explain_type_error(trace, &terr)
}
infer::Reborrow(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0312,
"lifetime of reference outlives \
lifetime of borrowed content...");
self.tcx.note_and_explain_region(&mut err,
"...the reference is valid for ",
sub,
"...");
self.tcx.note_and_explain_region(&mut err,
"...but the borrowed content is only valid for ",
sup,
"");
err
}
infer::ReborrowUpvar(span, ref upvar_id) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0313,
"lifetime of borrowed pointer outlives \
lifetime of captured variable `{}`...",
self.tcx.local_var_name_str(upvar_id.var_id));
self.tcx.note_and_explain_region(&mut err,
"...the borrowed pointer is valid for ",
sub,
"...");
self.tcx.note_and_explain_region(&mut err,
&format!("...but `{}` is only valid for ",
self.tcx.local_var_name_str(upvar_id.var_id)),
sup,
"");
err
}
infer::InfStackClosure(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0314,
"closure outlives stack frame");
self.tcx.note_and_explain_region(&mut err,
"...the closure must be valid for ",
sub,
"...");
self.tcx.note_and_explain_region(&mut err,
"...but the closure's stack frame is only valid for ",
sup,
"");
err
}
infer::InvokeClosure(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0315,
"cannot invoke closure outside of its lifetime");
self.tcx.note_and_explain_region(&mut err,
"the closure is only valid for ",
sup,
"");
err
}
infer::DerefPointer(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0473,
"dereference of reference outside its lifetime");
self.tcx.note_and_explain_region(&mut err,
"the reference is only valid for ",
sup,
"");
err
}
infer::FreeVariable(span, id) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0474,
"captured variable `{}` does not outlive the enclosing closure",
self.tcx.local_var_name_str(id));
self.tcx.note_and_explain_region(&mut err,
"captured variable is valid for ",
sup,
"");
self.tcx.note_and_explain_region(&mut err,
"closure is valid for ",
sub,
"");
err
}
infer::IndexSlice(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0475,
"index of slice outside its lifetime");
self.tcx.note_and_explain_region(&mut err,
"the slice is only valid for ",
sup,
"");
err
}
infer::RelateObjectBound(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0476,
"lifetime of the source pointer does not outlive \
lifetime bound of the object type");
self.tcx.note_and_explain_region(&mut err,
"object type is valid for ",
sub,
"");
self.tcx.note_and_explain_region(&mut err,
"source pointer is only valid for ",
sup,
"");
err
}
infer::RelateParamBound(span, ty) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0477,
"the type `{}` does not fulfill the required lifetime",
self.ty_to_string(ty));
self.tcx.note_and_explain_region(&mut err,
"type must outlive ",
sub,
"");
err
}
infer::RelateRegionParamBound(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0478,
"lifetime bound not satisfied");
self.tcx.note_and_explain_region(&mut err,
"lifetime parameter instantiated with ",
sup,
"");
self.tcx.note_and_explain_region(&mut err,
"but lifetime parameter must outlive ",
sub,
"");
err
}
infer::RelateDefaultParamBound(span, ty) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0479,
"the type `{}` (provided as the value of \
a type parameter) is not valid at this point",
self.ty_to_string(ty));
self.tcx.note_and_explain_region(&mut err,
"type must outlive ",
sub,
"");
err
}
infer::CallRcvr(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0480,
"lifetime of method receiver does not outlive \
the method call");
self.tcx.note_and_explain_region(&mut err,
"the receiver is only valid for ",
sup,
"");
err
}
infer::CallArg(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0481,
"lifetime of function argument does not outlive \
the function call");
self.tcx.note_and_explain_region(&mut err,
"the function argument is only valid for ",
sup,
"");
err
}
infer::CallReturn(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0482,
"lifetime of return value does not outlive \
the function call");
self.tcx.note_and_explain_region(&mut err,
"the return value is only valid for ",
sup,
"");
err
}
infer::Operand(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0483,
"lifetime of operand does not outlive \
the operation");
self.tcx.note_and_explain_region(&mut err,
"the operand is only valid for ",
sup,
"");
err
}
infer::AddrOf(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0484,
"reference is not valid at the time of borrow");
self.tcx.note_and_explain_region(&mut err,
"the borrow is only valid for ",
sup,
"");
err
}
infer::AutoBorrow(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0485,
"automatically reference is not valid \
at the time of borrow");
self.tcx.note_and_explain_region(&mut err,
"the automatic borrow is only valid for ",
sup,
"");
err
}
infer::ExprTypeIsNotInScope(t, span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0486,
"type of expression contains references \
that are not valid during the expression: `{}`",
self.ty_to_string(t));
self.tcx.note_and_explain_region(&mut err,
"type is only valid for ",
sup,
"");
err
}
infer::SafeDestructor(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0487,
"unsafe use of destructor: destructor might be called \
while references are dead");
// FIXME (22171): terms "super/subregion" are suboptimal
self.tcx.note_and_explain_region(&mut err,
"superregion: ",
sup,
"");
self.tcx.note_and_explain_region(&mut err,
"subregion: ",
sub,
"");
err
}
infer::BindingTypeIsNotValidAtDecl(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0488,
"lifetime of variable does not enclose its declaration");
self.tcx.note_and_explain_region(&mut err,
"the variable is only valid for ",
sup,
"");
err
}
infer::ParameterInScope(_, span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0489,
"type/lifetime parameter not in scope here");
self.tcx.note_and_explain_region(&mut err,
"the parameter is only valid for ",
sub,
"");
err
}
infer::DataBorrowed(ty, span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0490,
"a value of type `{}` is borrowed for too long",
self.ty_to_string(ty));
self.tcx.note_and_explain_region(&mut err, "the type is valid for ", sub, "");
self.tcx.note_and_explain_region(&mut err, "but the borrow lasts for ", sup, "");
err
}
infer::ReferenceOutlivesReferent(ty, span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0491,
"in type `{}`, reference has a longer lifetime \
than the data it references",
self.ty_to_string(ty));
self.tcx.note_and_explain_region(&mut err,