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Auto merge of #65038 - Centril:rollup-m83dpfh, r=Centril
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Rollup of 7 pull requests

Successful merges:

 - #63678 (Improve HRTB error span when -Zno-leak-check is used)
 - #64931 (Reword E0392 slightly)
 - #64959 (syntax: improve parameter without type suggestions)
 - #64975 (Implement Clone::clone_from for LinkedList)
 - #64993 (BacktraceStatus: add Eq impl)
 - #64998 (Filter out RLS output directories on tidy runs)
 - #65010 (Compare `primary` with maximum of `children`s' line num instead of dropping it)

Failed merges:

r? @ghost
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bors committed Oct 3, 2019
2 parents 2daa404 + d5a0765 commit c6293e3
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Showing 41 changed files with 357 additions and 65 deletions.
13 changes: 13 additions & 0 deletions src/liballoc/collections/linked_list.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1197,6 +1197,19 @@ impl<T: Clone> Clone for LinkedList<T> {
fn clone(&self) -> Self {
self.iter().cloned().collect()
}

fn clone_from(&mut self, other: &Self) {
let mut iter_other = other.iter();
if self.len() > other.len() {
self.split_off(other.len());
}
for (elem, elem_other) in self.iter_mut().zip(&mut iter_other) {
elem.clone_from(elem_other);
}
if !iter_other.is_empty() {
self.extend(iter_other.cloned());
}
}
}

#[stable(feature = "rust1", since = "1.0.0")]
Expand Down
43 changes: 43 additions & 0 deletions src/liballoc/collections/linked_list/tests.rs
Original file line number Diff line number Diff line change
Expand Up @@ -110,6 +110,49 @@ fn test_append() {
check_links(&n);
}

#[test]
fn test_clone_from() {
// Short cloned from long
{
let v = vec![1, 2, 3, 4, 5];
let u = vec![8, 7, 6, 2, 3, 4, 5];
let mut m = list_from(&v);
let n = list_from(&u);
m.clone_from(&n);
check_links(&m);
assert_eq!(m, n);
for elt in u {
assert_eq!(m.pop_front(), Some(elt))
}
}
// Long cloned from short
{
let v = vec![1, 2, 3, 4, 5];
let u = vec![6, 7, 8];
let mut m = list_from(&v);
let n = list_from(&u);
m.clone_from(&n);
check_links(&m);
assert_eq!(m, n);
for elt in u {
assert_eq!(m.pop_front(), Some(elt))
}
}
// Two equal length lists
{
let v = vec![1, 2, 3, 4, 5];
let u = vec![9, 8, 1, 2, 3];
let mut m = list_from(&v);
let n = list_from(&u);
m.clone_from(&n);
check_links(&m);
assert_eq!(m, n);
for elt in u {
assert_eq!(m.pop_front(), Some(elt))
}
}
}

#[test]
fn test_insert_prev() {
let mut m = list_from(&[0, 2, 4, 6, 8]);
Expand Down
16 changes: 14 additions & 2 deletions src/librustc/infer/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -418,15 +418,27 @@ pub enum NLLRegionVariableOrigin {
/// from a `for<'a> T` binder). Meant to represent "any region".
Placeholder(ty::PlaceholderRegion),

Existential,
Existential {
/// If this is true, then this variable was created to represent a lifetime
/// bound in a `for` binder. For example, it might have been created to
/// represent the lifetime `'a` in a type like `for<'a> fn(&'a u32)`.
/// Such variables are created when we are trying to figure out if there
/// is any valid instantiation of `'a` that could fit into some scenario.
///
/// This is used to inform error reporting: in the case that we are trying to
/// determine whether there is any valid instantiation of a `'a` variable that meets
/// some constraint C, we want to blame the "source" of that `for` type,
/// rather than blaming the source of the constraint C.
from_forall: bool
},
}

impl NLLRegionVariableOrigin {
pub fn is_universal(self) -> bool {
match self {
NLLRegionVariableOrigin::FreeRegion => true,
NLLRegionVariableOrigin::Placeholder(..) => true,
NLLRegionVariableOrigin::Existential => false,
NLLRegionVariableOrigin::Existential{ .. } => false,
}
}

Expand Down
4 changes: 2 additions & 2 deletions src/librustc/infer/nll_relate/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -93,7 +93,7 @@ pub trait TypeRelatingDelegate<'tcx> {
/// we will invoke this method to instantiate `'a` with an
/// inference variable (though `'b` would be instantiated first,
/// as a placeholder).
fn next_existential_region_var(&mut self) -> ty::Region<'tcx>;
fn next_existential_region_var(&mut self, was_placeholder: bool) -> ty::Region<'tcx>;

/// Creates a new region variable representing a
/// higher-ranked region that is instantiated universally.
Expand Down Expand Up @@ -193,7 +193,7 @@ where
let placeholder = ty::PlaceholderRegion { universe, name: br };
delegate.next_placeholder_region(placeholder)
} else {
delegate.next_existential_region_var()
delegate.next_existential_region_var(true)
}
}
};
Expand Down
3 changes: 2 additions & 1 deletion src/librustc_errors/emitter.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1026,7 +1026,8 @@ impl EmitterWriter {
children.iter()
.map(|sub| self.get_multispan_max_line_num(&sub.span))
.max()
.unwrap_or(primary)
.unwrap_or(0)
.max(primary)
}

/// Adds a left margin to every line but the first, given a padding length and the label being
Expand Down
Original file line number Diff line number Diff line change
Expand Up @@ -97,9 +97,11 @@ impl<'tcx> RegionInferenceContext<'tcx> {
&self,
body: &Body<'tcx>,
from_region: RegionVid,
from_region_origin: NLLRegionVariableOrigin,
target_test: impl Fn(RegionVid) -> bool,
) -> (ConstraintCategory, bool, Span) {
debug!("best_blame_constraint(from_region={:?})", from_region);
debug!("best_blame_constraint(from_region={:?}, from_region_origin={:?})",
from_region, from_region_origin);

// Find all paths
let (path, target_region) =
Expand Down Expand Up @@ -152,19 +154,85 @@ impl<'tcx> RegionInferenceContext<'tcx> {
// we still want to screen for an "interesting" point to
// highlight (e.g., a call site or something).
let target_scc = self.constraint_sccs.scc(target_region);
let best_choice = (0..path.len()).rev().find(|&i| {
let constraint = path[i];
let mut range = 0..path.len();

// As noted above, when reporting an error, there is typically a chain of constraints
// leading from some "source" region which must outlive some "target" region.
// In most cases, we prefer to "blame" the constraints closer to the target --
// but there is one exception. When constraints arise from higher-ranked subtyping,
// we generally prefer to blame the source value,
// as the "target" in this case tends to be some type annotation that the user gave.
// Therefore, if we find that the region origin is some instantiation
// of a higher-ranked region, we start our search from the "source" point
// rather than the "target", and we also tweak a few other things.
//
// An example might be this bit of Rust code:
//
// ```rust
// let x: fn(&'static ()) = |_| {};
// let y: for<'a> fn(&'a ()) = x;
// ```
//
// In MIR, this will be converted into a combination of assignments and type ascriptions.
// In particular, the 'static is imposed through a type ascription:
//
// ```rust
// x = ...;
// AscribeUserType(x, fn(&'static ())
// y = x;
// ```
//
// We wind up ultimately with constraints like
//
// ```rust
// !a: 'temp1 // from the `y = x` statement
// 'temp1: 'temp2
// 'temp2: 'static // from the AscribeUserType
// ```
//
// and here we prefer to blame the source (the y = x statement).
let blame_source = match from_region_origin {
NLLRegionVariableOrigin::FreeRegion
| NLLRegionVariableOrigin::Existential { from_forall: false } => {
true
}
NLLRegionVariableOrigin::Placeholder(_)
| NLLRegionVariableOrigin::Existential { from_forall: true } => {
false
}
};

let find_region = |i: &usize| {
let constraint = path[*i];

let constraint_sup_scc = self.constraint_sccs.scc(constraint.sup);

match categorized_path[i].0 {
ConstraintCategory::OpaqueType | ConstraintCategory::Boring |
ConstraintCategory::BoringNoLocation | ConstraintCategory::Internal => false,
ConstraintCategory::TypeAnnotation | ConstraintCategory::Return |
ConstraintCategory::Yield => true,
_ => constraint_sup_scc != target_scc,
if blame_source {
match categorized_path[*i].0 {
ConstraintCategory::OpaqueType | ConstraintCategory::Boring |
ConstraintCategory::BoringNoLocation | ConstraintCategory::Internal => false,
ConstraintCategory::TypeAnnotation | ConstraintCategory::Return |
ConstraintCategory::Yield => true,
_ => constraint_sup_scc != target_scc,
}
} else {
match categorized_path[*i].0 {
ConstraintCategory::OpaqueType | ConstraintCategory::Boring |
ConstraintCategory::BoringNoLocation | ConstraintCategory::Internal => false,
_ => true
}
}
});
};

let best_choice = if blame_source {
range.rev().find(find_region)
} else {
range.find(find_region)
};

debug!("best_blame_constraint: best_choice={:?} blame_source={}",
best_choice, blame_source);

if let Some(i) = best_choice {
if let Some(next) = categorized_path.get(i + 1) {
if categorized_path[i].0 == ConstraintCategory::Return
Expand Down Expand Up @@ -300,12 +368,13 @@ impl<'tcx> RegionInferenceContext<'tcx> {
infcx: &'a InferCtxt<'a, 'tcx>,
mir_def_id: DefId,
fr: RegionVid,
fr_origin: NLLRegionVariableOrigin,
outlived_fr: RegionVid,
renctx: &mut RegionErrorNamingCtx,
) -> DiagnosticBuilder<'a> {
debug!("report_error(fr={:?}, outlived_fr={:?})", fr, outlived_fr);

let (category, _, span) = self.best_blame_constraint(body, fr, |r| {
let (category, _, span) = self.best_blame_constraint(body, fr, fr_origin, |r| {
self.provides_universal_region(r, fr, outlived_fr)
});

Expand Down Expand Up @@ -712,6 +781,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
let (category, from_closure, span) = self.best_blame_constraint(
body,
borrow_region,
NLLRegionVariableOrigin::FreeRegion,
|r| self.provides_universal_region(r, borrow_region, outlived_region)
);

Expand Down Expand Up @@ -771,11 +841,13 @@ impl<'tcx> RegionInferenceContext<'tcx> {
&self,
body: &Body<'tcx>,
fr1: RegionVid,
fr1_origin: NLLRegionVariableOrigin,
fr2: RegionVid,
) -> (ConstraintCategory, Span) {
let (category, _, span) = self.best_blame_constraint(
body,
fr1,
fr1_origin,
|r| self.provides_universal_region(r, fr1, fr2),
);
(category, span)
Expand Down Expand Up @@ -828,7 +900,9 @@ impl<'tcx> RegionInferenceContext<'tcx> {
universe1.cannot_name(placeholder.universe)
}

NLLRegionVariableOrigin::FreeRegion | NLLRegionVariableOrigin::Existential => false,
NLLRegionVariableOrigin::FreeRegion | NLLRegionVariableOrigin::Existential { .. } => {
false
}
}
}
}
14 changes: 9 additions & 5 deletions src/librustc_mir/borrow_check/nll/region_infer/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -406,7 +406,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
}
}

NLLRegionVariableOrigin::Existential => {
NLLRegionVariableOrigin::Existential { .. } => {
// For existential, regions, nothing to do.
}
}
Expand Down Expand Up @@ -1348,7 +1348,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
self.check_bound_universal_region(infcx, body, mir_def_id, fr, placeholder);
}

NLLRegionVariableOrigin::Existential => {
NLLRegionVariableOrigin::Existential { .. } => {
// nothing to check here
}
}
Expand Down Expand Up @@ -1461,7 +1461,8 @@ impl<'tcx> RegionInferenceContext<'tcx> {
debug!("check_universal_region: fr_minus={:?}", fr_minus);

let blame_span_category =
self.find_outlives_blame_span(body, longer_fr, shorter_fr);
self.find_outlives_blame_span(body, longer_fr,
NLLRegionVariableOrigin::FreeRegion,shorter_fr);

// Grow `shorter_fr` until we find some non-local regions. (We
// always will.) We'll call them `shorter_fr+` -- they're ever
Expand Down Expand Up @@ -1494,6 +1495,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
infcx,
mir_def_id,
longer_fr,
NLLRegionVariableOrigin::FreeRegion,
shorter_fr,
region_naming,
);
Expand Down Expand Up @@ -1547,7 +1549,9 @@ impl<'tcx> RegionInferenceContext<'tcx> {
};

// Find the code to blame for the fact that `longer_fr` outlives `error_fr`.
let (_, span) = self.find_outlives_blame_span(body, longer_fr, error_region);
let (_, span) = self.find_outlives_blame_span(
body, longer_fr, NLLRegionVariableOrigin::Placeholder(placeholder), error_region
);

// Obviously, this error message is far from satisfactory.
// At present, though, it only appears in unit tests --
Expand Down Expand Up @@ -1608,7 +1612,7 @@ impl<'tcx> RegionDefinition<'tcx> {

let origin = match rv_origin {
RegionVariableOrigin::NLL(origin) => origin,
_ => NLLRegionVariableOrigin::Existential,
_ => NLLRegionVariableOrigin::Existential { from_forall: false },
};

Self { origin, universe, external_name: None }
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_mir/borrow_check/nll/renumber.rs
Original file line number Diff line number Diff line change
Expand Up @@ -35,7 +35,7 @@ where
infcx
.tcx
.fold_regions(value, &mut false, |_region, _depth| {
let origin = NLLRegionVariableOrigin::Existential;
let origin = NLLRegionVariableOrigin::Existential { from_forall: false };
infcx.next_nll_region_var(origin)
})
}
Expand Down
8 changes: 5 additions & 3 deletions src/librustc_mir/borrow_check/nll/type_check/relate_tys.rs
Original file line number Diff line number Diff line change
Expand Up @@ -66,9 +66,9 @@ impl TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, 'tcx> {
self.infcx.create_next_universe()
}

fn next_existential_region_var(&mut self) -> ty::Region<'tcx> {
fn next_existential_region_var(&mut self, from_forall: bool) -> ty::Region<'tcx> {
if let Some(_) = &mut self.borrowck_context {
let origin = NLLRegionVariableOrigin::Existential;
let origin = NLLRegionVariableOrigin::Existential { from_forall };
self.infcx.next_nll_region_var(origin)
} else {
self.infcx.tcx.lifetimes.re_erased
Expand All @@ -88,7 +88,9 @@ impl TypeRelatingDelegate<'tcx> for NllTypeRelatingDelegate<'_, '_, 'tcx> {

fn generalize_existential(&mut self, universe: ty::UniverseIndex) -> ty::Region<'tcx> {
self.infcx
.next_nll_region_var_in_universe(NLLRegionVariableOrigin::Existential, universe)
.next_nll_region_var_in_universe(NLLRegionVariableOrigin::Existential {
from_forall: false
}, universe)
}

fn push_outlives(&mut self, sup: ty::Region<'tcx>, sub: ty::Region<'tcx>) {
Expand Down
2 changes: 1 addition & 1 deletion src/librustc_traits/chalk_context/unify.rs
Original file line number Diff line number Diff line change
Expand Up @@ -65,7 +65,7 @@ impl TypeRelatingDelegate<'tcx> for &mut ChalkTypeRelatingDelegate<'_, 'tcx> {
self.infcx.create_next_universe()
}

fn next_existential_region_var(&mut self) -> ty::Region<'tcx> {
fn next_existential_region_var(&mut self, _was_placeholder: bool) -> ty::Region<'tcx> {
self.infcx.next_region_var(RegionVariableOrigin::MiscVariable(DUMMY_SP))
}

Expand Down
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