bjoernager/rust
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make suggestion stuff not swallow errors

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The older code would sometimes swallow errors or fail to produce a
suggestion. The newer code does not. However, just printing everything
would produce a bunch of new and kind of annoying errors, so continue
to swallow `T: 'a` errors so long as there are other things to show.
This commit is contained in:
Niko Matsakis 2016-03-18 14:47:40 -04:00
parent 5abacd36f0
commit bca07b5ebb
6 changed files with 155 additions and 89 deletions
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214
src/librustc/middle/infer/error_reporting.rs
View file

@ -68,6 +68,7 @@ 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;
@ -232,7 +233,7 @@ pub trait ErrorReporting<'tcx> {
errors: &Vec<RegionResolutionError<'tcx>>);
fn process_errors(&self, errors: &Vec<RegionResolutionError<'tcx>>)
-> Vec<RegionResolutionError<'tcx>>;
-> Option<Vec<RegionResolutionError<'tcx>>>;
fn report_type_error(&self,
trace: TypeTrace<'tcx>,
@ -246,7 +247,8 @@ pub trait ErrorReporting<'tcx> {
fn report_and_explain_type_error(&self,
trace: TypeTrace<'tcx>,
terr: &TypeError<'tcx>);
terr: &TypeError<'tcx>)
-> DiagnosticBuilder<'tcx>;
fn values_str(&self, values: &ValuePairs<'tcx>) -> Option<String>;
@ -258,7 +260,8 @@ pub trait ErrorReporting<'tcx> {
fn report_concrete_failure(&self,
origin: SubregionOrigin<'tcx>,
sub: Region,
sup: Region);
sup: Region)
-> DiagnosticBuilder<'tcx>;
fn report_generic_bound_failure(&self,
origin: SubregionOrigin<'tcx>,
@ -273,8 +276,7 @@ pub trait ErrorReporting<'tcx> {
sup_region: Region);
fn report_processed_errors(&self,
var_origin: &[RegionVariableOrigin],
trace_origin: &[(TypeTrace<'tcx>, TypeError<'tcx>)],
origins: &[ProcessedErrorOrigin<'tcx>],
same_regions: &[SameRegions]);
fn give_suggestion(&self, err: &mut DiagnosticBuilder, same_regions: &[SameRegions]);
@ -303,12 +305,19 @@ trait ErrorReportingHelpers<'tcx> {
impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
fn report_region_errors(&self,
errors: &Vec<RegionResolutionError<'tcx>>) {
let p_errors = self.process_errors(errors);
let errors = if p_errors.is_empty() { errors } else { &p_errors };
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 {
match error.clone() {
ConcreteFailure(origin, sub, sup) => {
self.report_concrete_failure(origin, sub, sup);
self.report_concrete_failure(origin, sub, sup).emit();
}
GenericBoundFailure(kind, param_ty, sub) => {
@ -323,13 +332,10 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
sup_origin, sup_r);
}
ProcessedErrors(ref var_origins,
ref trace_origins,
ProcessedErrors(ref origins,
ref same_regions) => {
if !same_regions.is_empty() {
self.report_processed_errors(&var_origins[..],
&trace_origins[..],
&same_regions[..]);
self.report_processed_errors(origins, same_regions);
}
}
}
@ -341,46 +347,73 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
// 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)
// 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>>)
-> Vec<RegionResolutionError<'tcx>> {
-> Option<Vec<RegionResolutionError<'tcx>>> {
debug!("process_errors()");
let mut var_origins = Vec::new();
let mut trace_origins = Vec::new();
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();
let mut processed_errors = 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 {
match error.clone() {
ConcreteFailure(origin, sub, sup) => {
match *error {
ConcreteFailure(ref origin, sub, sup) => {
debug!("processing ConcreteFailure");
let trace = match origin {
infer::Subtype(trace) => Some(trace),
_ => None,
};
match free_regions_from_same_fn(self.tcx, sub, sup) {
Some(ref same_frs) if trace.is_some() => {
let trace = trace.unwrap();
let terr = TypeError::RegionsDoesNotOutlive(sup,
sub);
trace_origins.push((trace, terr));
Some(ref same_frs) => {
origins.push(
ProcessedErrorOrigin::ConcreteFailure(
origin.clone(),
sub,
sup));
append_to_same_regions(&mut same_regions, same_frs);
}
_ => processed_errors.push((*error).clone()),
_ => {
other_errors.push(error.clone());
}
}
}
SubSupConflict(var_origin, _, sub_r, _, sup_r) => {
SubSupConflict(ref var_origin, _, sub_r, _, sup_r) => {
debug!("processing SubSupConflict sub: {:?} sup: {:?}", sub_r, sup_r);
match free_regions_from_same_fn(self.tcx, sub_r, sup_r) {
Some(ref same_frs) => {
var_origins.push(var_origin);
origins.push(
ProcessedErrorOrigin::VariableFailure(
var_origin.clone()));
append_to_same_regions(&mut same_regions, same_frs);
}
None => processed_errors.push((*error).clone()),
None => {
other_errors.push(error.clone());
}
}
}
_ => () // This shouldn't happen
GenericBoundFailure(ref origin, ref kind, region) => {
bound_failures.push((origin.clone(), kind.clone(), region));
}
ProcessedErrors(..) => {
panic!("should not encounter a `ProcessedErrors` yet: {:?}", error)
}
}
}
// 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 {
@ -390,16 +423,39 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
if sr.scope_id != common_scope_id {
debug!("returning empty result from process_errors because
{} != {}", sr.scope_id, common_scope_id);
return vec!();
return None;
}
}
let pe = ProcessedErrors(var_origins, trace_origins, same_regions);
assert!(origins.len() > 0);
let pe = ProcessedErrors(origins, same_regions);
debug!("errors processed: {:?}", pe);
processed_errors.push(pe);
}
return processed_errors;
// 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,
@ -459,11 +515,12 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
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 &mut *same_regions {
if sr.contains(&sup_fr.bound_region)
&& scope_id == sr.scope_id {
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
}
@ -569,11 +626,12 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
fn report_and_explain_type_error(&self,
trace: TypeTrace<'tcx>,
terr: &TypeError<'tcx>) {
terr: &TypeError<'tcx>)
-> DiagnosticBuilder<'tcx> {
let span = trace.origin.span();
let mut err = self.report_type_error(trace, terr);
self.tcx.note_and_explain_type_err(&mut err, terr, span);
err.emit();
err
}
/// Returns a string of the form "expected `{}`, found `{}`", or None if this is a derived
@ -678,11 +736,12 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
fn report_concrete_failure(&self,
origin: SubregionOrigin<'tcx>,
sub: Region,
sup: Region) {
sup: Region)
-> DiagnosticBuilder<'tcx> {
match origin {
infer::Subtype(trace) => {
let terr = TypeError::RegionsDoesNotOutlive(sup, sub);
self.report_and_explain_type_error(trace, &terr);
self.report_and_explain_type_error(trace, &terr)
}
infer::Reborrow(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0312,
@ -696,7 +755,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"...but the borrowed content is only valid for ",
sup,
"");
err.emit();
err
}
infer::ReborrowUpvar(span, ref upvar_id) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0313,
@ -712,7 +771,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
self.tcx.local_var_name_str(upvar_id.var_id)),
sup,
"");
err.emit();
err
}
infer::InfStackClosure(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0314,
@ -725,7 +784,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"...but the closure's stack frame is only valid for ",
sup,
"");
err.emit();
err
}
infer::InvokeClosure(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0315,
@ -734,7 +793,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"the closure is only valid for ",
sup,
"");
err.emit();
err
}
infer::DerefPointer(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0473,
@ -743,7 +802,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"the reference is only valid for ",
sup,
"");
err.emit();
err
}
infer::FreeVariable(span, id) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0474,
@ -757,7 +816,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"closure is valid for ",
sub,
"");
err.emit();
err
}
infer::IndexSlice(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0475,
@ -766,7 +825,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"the slice is only valid for ",
sup,
"");
err.emit();
err
}
infer::RelateObjectBound(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0476,
@ -780,7 +839,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"source pointer is only valid for ",
sup,
"");
err.emit();
err
}
infer::RelateParamBound(span, ty) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0477,
@ -790,7 +849,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"type must outlive ",
sub,
"");
err.emit();
err
}
infer::RelateRegionParamBound(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0478,
@ -803,7 +862,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"but lifetime parameter must outlive ",
sub,
"");
err.emit();
err
}
infer::RelateDefaultParamBound(span, ty) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0479,
@ -814,7 +873,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"type must outlive ",
sub,
"");
err.emit();
err
}
infer::CallRcvr(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0480,
@ -824,7 +883,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"the receiver is only valid for ",
sup,
"");
err.emit();
err
}
infer::CallArg(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0481,
@ -834,7 +893,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"the function argument is only valid for ",
sup,
"");
err.emit();
err
}
infer::CallReturn(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0482,
@ -844,7 +903,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"the return value is only valid for ",
sup,
"");
err.emit();
err
}
infer::Operand(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0483,
@ -854,7 +913,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"the operand is only valid for ",
sup,
"");
err.emit();
err
}
infer::AddrOf(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0484,
@ -863,7 +922,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"the borrow is only valid for ",
sup,
"");
err.emit();
err
}
infer::AutoBorrow(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0485,
@ -873,7 +932,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"the automatic borrow is only valid for ",
sup,
"");
err.emit();
err
}
infer::ExprTypeIsNotInScope(t, span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0486,
@ -884,7 +943,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"type is only valid for ",
sup,
"");
err.emit();
err
}
infer::SafeDestructor(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0487,
@ -899,7 +958,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"subregion: ",
sub,
"");
err.emit();
err
}
infer::BindingTypeIsNotValidAtDecl(span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0488,
@ -908,7 +967,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"the variable is only valid for ",
sup,
"");
err.emit();
err
}
infer::ParameterInScope(_, span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0489,
@ -917,7 +976,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"the parameter is only valid for ",
sub,
"");
err.emit();
err
}
infer::DataBorrowed(ty, span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0490,
@ -925,7 +984,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
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.emit();
err
}
infer::ReferenceOutlivesReferent(ty, span) => {
let mut err = struct_span_err!(self.tcx.sess, span, E0491,
@ -940,7 +999,7 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
"but the referenced data is only valid for ",
sup,
"");
err.emit();
err
}
}
}
@ -970,19 +1029,22 @@ impl<'a, 'tcx> ErrorReporting<'tcx> for InferCtxt<'a, 'tcx> {
}
fn report_processed_errors(&self,
var_origins: &[RegionVariableOrigin],
trace_origins: &[(TypeTrace<'tcx>, TypeError<'tcx>)],
origins: &[ProcessedErrorOrigin<'tcx>],
same_regions: &[SameRegions]) {
for (i, vo) in var_origins.iter().enumerate() {
let mut err = self.report_inference_failure(vo.clone());
if i == var_origins.len() - 1 {
for (i, origin) in origins.iter().enumerate() {
let mut err = match *origin {
ProcessedErrorOrigin::VariableFailure(ref var_origin) =>
self.report_inference_failure(var_origin.clone()),
ProcessedErrorOrigin::ConcreteFailure(ref sr_origin, sub, sup) =>
self.report_concrete_failure(sr_origin.clone(), sub, sup),
};
// attach the suggestion to the last such error
if i == origins.len() - 1 {
self.give_suggestion(&mut err, same_regions);
}
err.emit();
}
for &(ref trace, ref terr) in trace_origins {
self.report_and_explain_type_error(trace.clone(), terr);
err.emit();
}
}

10
src/librustc/middle/infer/mod.rs
View file

@ -407,7 +407,7 @@ pub fn common_supertype<'a, 'tcx>(cx: &InferCtxt<'a, 'tcx>,
match result {
Ok(t) => t,
Err(ref err) => {
cx.report_and_explain_type_error(trace, err);
cx.report_and_explain_type_error(trace, err).emit();
cx.tcx.types.err
}
}
@ -1396,7 +1396,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
found: actual
})
};
self.report_and_explain_type_error(trace, &err);
self.report_and_explain_type_error(trace, &err).emit();
}
pub fn report_conflicting_default_types(&self,
@ -1411,11 +1411,13 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
})
};
self.report_and_explain_type_error(trace,
self.report_and_explain_type_error(
trace,
&TypeError::TyParamDefaultMismatch(ExpectedFound {
expected: expected,
found: actual
}));
}))
.emit();
}
pub fn replace_late_bound_regions_with_fresh_var<T>(

12
src/librustc/middle/infer/region_inference/mod.rs
View file

@ -17,7 +17,7 @@ pub use self::CombineMapType::*;
pub use self::RegionResolutionError::*;
pub use self::VarValue::*;
use super::{RegionVariableOrigin, SubregionOrigin, TypeTrace, MiscVariable};
use super::{RegionVariableOrigin, SubregionOrigin, MiscVariable};
use super::unify_key;
use rustc_data_structures::graph::{self, Direction, NodeIndex};
@ -27,7 +27,6 @@ use middle::ty::{self, Ty, TyCtxt};
use middle::ty::{BoundRegion, Region, RegionVid};
use middle::ty::{ReEmpty, ReStatic, ReFree, ReEarlyBound};
use middle::ty::{ReLateBound, ReScope, ReVar, ReSkolemized, BrFresh};
use middle::ty::error::TypeError;
use util::common::indenter;
use util::nodemap::{FnvHashMap, FnvHashSet};
@ -152,11 +151,16 @@ pub enum RegionResolutionError<'tcx> {
/// more specific errors message by suggesting to the user where they
/// should put a lifetime. In those cases we process and put those errors
/// into `ProcessedErrors` before we do any reporting.
ProcessedErrors(Vec<RegionVariableOrigin>,
Vec<(TypeTrace<'tcx>, TypeError<'tcx>)>,
ProcessedErrors(Vec<ProcessedErrorOrigin<'tcx>>,
Vec<SameRegions>),
}
#[derive(Clone, Debug)]
pub enum ProcessedErrorOrigin<'tcx> {
ConcreteFailure(SubregionOrigin<'tcx>, Region, Region),
VariableFailure(RegionVariableOrigin),
}
/// SameRegions is used to group regions that we think are the same and would
/// like to indicate so to the user.
/// For example, the following function

4
src/test/compile-fail/issue-13058.rs
View file

@ -36,9 +36,5 @@ fn check<'r, I: Iterator<Item=usize>, T: Itble<'r, usize, I>>(cont: &T) -> bool
fn main() {
check((3, 5));
//~^ ERROR mismatched types
//~| expected `&_`
//~| found `(_, _)`
//~| expected &-ptr
//~| found tuple
//~| HELP run `rustc --explain E0308` to see a detailed explanation
}

2
src/test/compile-fail/lifetime-inference-give-expl-lifetime-param-3.rs
View file

@ -22,7 +22,7 @@ fn bar1<'a>(x: &Bar) -> (&'a i32, &'a i32, &'a i32) {
}
fn bar2<'a, 'b, 'c>(x: &Bar<'a, 'b, 'c>) -> (&'a i32, &'a i32, &'a i32) {
//~^ HELP: consider using an explicit lifetime parameter as shown: fn bar2<'a, 'b, 'c>(x: &'a Bar<'a, 'b, 'c>) -> (&'a i32, &'a i32, &'a i32)
//~^ HELP: consider using an explicit lifetime parameter as shown: fn bar2<'a, 'c>(x: &'a Bar<'a, 'a, 'c>) -> (&'a i32, &'a i32, &'a i32)
(x.bar, &x.baz, &x.baz)
//~^ ERROR E0312
//~| ERROR cannot infer

2
src/test/compile-fail/lifetime-inference-give-expl-lifetime-param.rs
View file

@ -39,6 +39,7 @@ struct Cat<'x, T> { cat: &'x isize, t: T }
struct Dog<'y> { dog: &'y isize }
fn cat2<'x, 'y>(x: Cat<'x, Dog<'y>>) -> &'x isize {
//~^ HELP consider using an explicit lifetime parameter as shown: fn cat2<'x>(x: Cat<'x, Dog<'x>>) -> &'x isize
x.t.dog //~ ERROR E0312
}
@ -48,6 +49,7 @@ struct Baz<'x> {
impl<'a> Baz<'a> {
fn baz2<'b>(&self, x: &isize) -> (&'b isize, &'b isize) {
//~^ HELP consider using an explicit lifetime parameter as shown: fn baz2<'b>(&self, x: &'b isize) -> (&'a isize, &'a isize)
(self.bar, x) //~ ERROR E0312
//~^ ERROR E0312
}