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Rollup merge of #96733 - SparrowLii:place_to_string, r=davidtwco
turn `append_place_to_string` from recursion into iteration This PR fixes the FIXME in the impl of `append_place_to_string` which turns `append_place_to_string` from recursion into iteration, meanwhile simplifying the code relatively.
This commit is contained in:
Guillaume Gomez
GitHub
commit
c3ddd59f5b
@ -1,5 +1,6 @@
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//! Borrow checker diagnostics.
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use itertools::Itertools;
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use rustc_const_eval::util::{call_kind, CallDesugaringKind};
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use rustc_errors::{Applicability, Diagnostic};
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use rustc_hir as hir;
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@ -161,158 +162,103 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> {
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}
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/// End-user visible description of `place` if one can be found.
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/// If the place is a temporary for instance, None will be returned.
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/// If the place is a temporary for instance, `None` will be returned.
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pub(super) fn describe_place(&self, place_ref: PlaceRef<'tcx>) -> Option<String> {
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self.describe_place_with_options(place_ref, IncludingDowncast(false))
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}
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/// End-user visible description of `place` if one can be found. If the
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/// place is a temporary for instance, None will be returned.
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/// `IncludingDowncast` parameter makes the function return `Err` if `ProjectionElem` is
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/// End-user visible description of `place` if one can be found. If the place is a temporary
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/// for instance, `None` will be returned.
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/// `IncludingDowncast` parameter makes the function return `None` if `ProjectionElem` is
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/// `Downcast` and `IncludingDowncast` is true
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pub(super) fn describe_place_with_options(
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&self,
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place: PlaceRef<'tcx>,
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including_downcast: IncludingDowncast,
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) -> Option<String> {
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let local = place.local;
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let mut autoderef_index = None;
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let mut buf = String::new();
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match self.append_place_to_string(place, &mut buf, false, &including_downcast) {
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Ok(()) => Some(buf),
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Err(()) => None,
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}
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}
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let mut ok = self.append_local_to_string(local, &mut buf);
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/// Appends end-user visible description of `place` to `buf`.
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fn append_place_to_string(
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&self,
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place: PlaceRef<'tcx>,
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buf: &mut String,
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mut autoderef: bool,
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including_downcast: &IncludingDowncast,
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) -> Result<(), ()> {
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match place {
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PlaceRef { local, projection: [] } => {
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self.append_local_to_string(local, buf)?;
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}
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PlaceRef { local, projection: [ProjectionElem::Deref] }
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if self.body.local_decls[local].is_ref_for_guard() =>
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{
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self.append_place_to_string(
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PlaceRef { local, projection: &[] },
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buf,
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autoderef,
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&including_downcast,
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)?;
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}
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PlaceRef { local, projection: [ProjectionElem::Deref] }
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if self.body.local_decls[local].is_ref_to_static() =>
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{
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let local_info = &self.body.local_decls[local].local_info;
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if let Some(box LocalInfo::StaticRef { def_id, .. }) = *local_info {
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buf.push_str(self.infcx.tcx.item_name(def_id).as_str());
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} else {
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unreachable!();
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for (index, elem) in place.projection.into_iter().enumerate() {
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match elem {
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ProjectionElem::Deref => {
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if index == 0 {
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if self.body.local_decls[local].is_ref_for_guard() {
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continue;
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}
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if let Some(box LocalInfo::StaticRef { def_id, .. }) =
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&self.body.local_decls[local].local_info
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{
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buf.push_str(self.infcx.tcx.item_name(*def_id).as_str());
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ok = Ok(());
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continue;
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}
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}
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if let Some(field) = self.is_upvar_field_projection(PlaceRef {
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local,
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projection: place.projection.split_at(index + 1).0,
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}) {
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let var_index = field.index();
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buf = self.upvars[var_index].place.to_string(self.infcx.tcx);
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ok = Ok(());
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if !self.upvars[var_index].by_ref {
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buf.insert(0, '*');
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}
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} else {
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if autoderef_index.is_none() {
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autoderef_index =
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match place.projection.into_iter().rev().find_position(|elem| {
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!matches!(
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elem,
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ProjectionElem::Deref | ProjectionElem::Downcast(..)
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)
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}) {
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Some((index, _)) => Some(place.projection.len() - index),
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None => Some(0),
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};
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}
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if index >= autoderef_index.unwrap() {
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buf.insert(0, '*');
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}
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}
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}
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ProjectionElem::Downcast(..) if including_downcast.0 => return None,
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ProjectionElem::Downcast(..) => (),
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ProjectionElem::Field(field, _ty) => {
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// FIXME(project-rfc_2229#36): print capture precisely here.
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if let Some(field) = self.is_upvar_field_projection(PlaceRef {
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local,
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projection: place.projection.split_at(index + 1).0,
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}) {
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buf = self.upvars[field.index()].place.to_string(self.infcx.tcx);
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ok = Ok(());
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} else {
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let field_name = self.describe_field(
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PlaceRef { local, projection: place.projection.split_at(index).0 },
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*field,
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);
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buf.push('.');
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buf.push_str(&field_name);
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}
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}
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ProjectionElem::Index(index) => {
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buf.push('[');
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if self.append_local_to_string(*index, &mut buf).is_err() {
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buf.push('_');
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}
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buf.push(']');
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}
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ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. } => {
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// Since it isn't possible to borrow an element on a particular index and
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// then use another while the borrow is held, don't output indices details
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// to avoid confusing the end-user
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buf.push_str("[..]");
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}
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}
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PlaceRef { local, projection: [proj_base @ .., elem] } => {
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match elem {
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ProjectionElem::Deref => {
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let upvar_field_projection = self.is_upvar_field_projection(place);
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if let Some(field) = upvar_field_projection {
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let var_index = field.index();
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let name = self.upvars[var_index].place.to_string(self.infcx.tcx);
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if self.upvars[var_index].by_ref {
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buf.push_str(&name);
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} else {
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buf.push('*');
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buf.push_str(&name);
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}
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} else {
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if autoderef {
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// FIXME turn this recursion into iteration
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self.append_place_to_string(
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PlaceRef { local, projection: proj_base },
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buf,
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autoderef,
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&including_downcast,
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)?;
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} else {
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buf.push('*');
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self.append_place_to_string(
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PlaceRef { local, projection: proj_base },
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buf,
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autoderef,
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&including_downcast,
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)?;
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}
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}
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}
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ProjectionElem::Downcast(..) => {
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self.append_place_to_string(
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PlaceRef { local, projection: proj_base },
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buf,
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autoderef,
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&including_downcast,
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)?;
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if including_downcast.0 {
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return Err(());
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}
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}
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ProjectionElem::Field(field, _ty) => {
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autoderef = true;
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// FIXME(project-rfc_2229#36): print capture precisely here.
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let upvar_field_projection = self.is_upvar_field_projection(place);
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if let Some(field) = upvar_field_projection {
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let var_index = field.index();
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let name = self.upvars[var_index].place.to_string(self.infcx.tcx);
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buf.push_str(&name);
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} else {
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let field_name = self
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.describe_field(PlaceRef { local, projection: proj_base }, *field);
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self.append_place_to_string(
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PlaceRef { local, projection: proj_base },
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buf,
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autoderef,
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&including_downcast,
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)?;
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buf.push('.');
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buf.push_str(&field_name);
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}
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}
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ProjectionElem::Index(index) => {
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autoderef = true;
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self.append_place_to_string(
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PlaceRef { local, projection: proj_base },
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buf,
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autoderef,
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&including_downcast,
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)?;
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buf.push('[');
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if self.append_local_to_string(*index, buf).is_err() {
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buf.push('_');
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}
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buf.push(']');
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}
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ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. } => {
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autoderef = true;
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// Since it isn't possible to borrow an element on a particular index and
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// then use another while the borrow is held, don't output indices details
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// to avoid confusing the end-user
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self.append_place_to_string(
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PlaceRef { local, projection: proj_base },
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buf,
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autoderef,
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&including_downcast,
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)?;
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buf.push_str("[..]");
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}
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};
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}
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}
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Ok(())
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ok.ok().map(|_| buf)
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}
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/// Appends end-user visible description of the `local` place to `buf`. If `local` doesn't have
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