diff options
| -rw-r--r-- | compiler/rustc_borrowck/src/diagnostics/mod.rs | 210 |
1 files changed, 78 insertions, 132 deletions
diff --git a/compiler/rustc_borrowck/src/diagnostics/mod.rs b/compiler/rustc_borrowck/src/diagnostics/mod.rs index 368c0be794b..05d29503180 100644 --- a/compiler/rustc_borrowck/src/diagnostics/mod.rs +++ b/compiler/rustc_borrowck/src/diagnostics/mod.rs @@ -1,5 +1,6 @@ //! Borrow checker diagnostics. +use itertools::Itertools; use rustc_const_eval::util::{call_kind, CallDesugaringKind}; use rustc_errors::{Applicability, Diagnostic}; use rustc_hir as hir; @@ -161,158 +162,103 @@ impl<'cx, 'tcx> MirBorrowckCtxt<'cx, 'tcx> { } /// End-user visible description of `place` if one can be found. - /// If the place is a temporary for instance, None will be returned. + /// If the place is a temporary for instance, `None` will be returned. pub(super) fn describe_place(&self, place_ref: PlaceRef<'tcx>) -> Option<String> { self.describe_place_with_options(place_ref, IncludingDowncast(false)) } - /// End-user visible description of `place` if one can be found. If the - /// place is a temporary for instance, None will be returned. - /// `IncludingDowncast` parameter makes the function return `Err` if `ProjectionElem` is + /// End-user visible description of `place` if one can be found. If the place is a temporary + /// for instance, `None` will be returned. + /// `IncludingDowncast` parameter makes the function return `None` if `ProjectionElem` is /// `Downcast` and `IncludingDowncast` is true pub(super) fn describe_place_with_options( &self, place: PlaceRef<'tcx>, including_downcast: IncludingDowncast, ) -> Option<String> { + let local = place.local; + let mut autoderef_index = None; let mut buf = String::new(); - match self.append_place_to_string(place, &mut buf, false, &including_downcast) { - Ok(()) => Some(buf), - Err(()) => None, - } - } - - /// Appends end-user visible description of `place` to `buf`. - fn append_place_to_string( - &self, - place: PlaceRef<'tcx>, - buf: &mut String, - mut autoderef: bool, - including_downcast: &IncludingDowncast, - ) -> Result<(), ()> { - match place { - PlaceRef { local, projection: [] } => { - self.append_local_to_string(local, buf)?; - } - PlaceRef { local, projection: [ProjectionElem::Deref] } - if self.body.local_decls[local].is_ref_for_guard() => - { - self.append_place_to_string( - PlaceRef { local, projection: &[] }, - buf, - autoderef, - &including_downcast, - )?; - } - PlaceRef { local, projection: [ProjectionElem::Deref] } - if self.body.local_decls[local].is_ref_to_static() => - { - let local_info = &self.body.local_decls[local].local_info; - if let Some(box LocalInfo::StaticRef { def_id, .. }) = *local_info { - buf.push_str(self.infcx.tcx.item_name(def_id).as_str()); - } else { - unreachable!(); - } - } - PlaceRef { local, projection: [proj_base @ .., elem] } => { - match elem { - ProjectionElem::Deref => { - let upvar_field_projection = self.is_upvar_field_projection(place); - if let Some(field) = upvar_field_projection { - let var_index = field.index(); - let name = self.upvars[var_index].place.to_string(self.infcx.tcx); - if self.upvars[var_index].by_ref { - buf.push_str(&name); - } else { - buf.push('*'); - buf.push_str(&name); - } - } else { - if autoderef { - // FIXME turn this recursion into iteration - self.append_place_to_string( - PlaceRef { local, projection: proj_base }, - buf, - autoderef, - &including_downcast, - )?; - } else { - buf.push('*'); - self.append_place_to_string( - PlaceRef { local, projection: proj_base }, - buf, - autoderef, - &including_downcast, - )?; - } + let mut ok = self.append_local_to_string(local, &mut buf); + + for (index, elem) in place.projection.into_iter().enumerate() { + match elem { + ProjectionElem::Deref => { + if index == 0 { + if self.body.local_decls[local].is_ref_for_guard() { + continue; } - } - ProjectionElem::Downcast(..) => { - self.append_place_to_string( - PlaceRef { local, projection: proj_base }, - buf, - autoderef, - &including_downcast, - )?; - if including_downcast.0 { - return Err(()); + if let Some(box LocalInfo::StaticRef { def_id, .. }) = + &self.body.local_decls[local].local_info + { + buf.push_str(self.infcx.tcx.item_name(*def_id).as_str()); + ok = Ok(()); + continue; } } - ProjectionElem::Field(field, _ty) => { - autoderef = true; - - // FIXME(project-rfc_2229#36): print capture precisely here. - let upvar_field_projection = self.is_upvar_field_projection(place); - if let Some(field) = upvar_field_projection { - let var_index = field.index(); - let name = self.upvars[var_index].place.to_string(self.infcx.tcx); - buf.push_str(&name); - } else { - let field_name = self - .describe_field(PlaceRef { local, projection: proj_base }, *field); - self.append_place_to_string( - PlaceRef { local, projection: proj_base }, - buf, - autoderef, - &including_downcast, - )?; - buf.push('.'); - buf.push_str(&field_name); + if let Some(field) = self.is_upvar_field_projection(PlaceRef { + local, + projection: place.projection.split_at(index + 1).0, + }) { + let var_index = field.index(); + buf = self.upvars[var_index].place.to_string(self.infcx.tcx); + ok = Ok(()); + if !self.upvars[var_index].by_ref { + buf.insert(0, '*'); } - } - ProjectionElem::Index(index) => { - autoderef = true; - - self.append_place_to_string( - PlaceRef { local, projection: proj_base }, - buf, - autoderef, - &including_downcast, - )?; - buf.push('['); - if self.append_local_to_string(*index, buf).is_err() { - buf.push('_'); + } else { + if autoderef_index.is_none() { + autoderef_index = + match place.projection.into_iter().rev().find_position(|elem| { + !matches!( + elem, + ProjectionElem::Deref | ProjectionElem::Downcast(..) + ) + }) { + Some((index, _)) => Some(place.projection.len() - index), + None => Some(0), + }; + } + if index >= autoderef_index.unwrap() { + buf.insert(0, '*'); } - buf.push(']'); } - ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. } => { - autoderef = true; - // Since it isn't possible to borrow an element on a particular index and - // then use another while the borrow is held, don't output indices details - // to avoid confusing the end-user - self.append_place_to_string( - PlaceRef { local, projection: proj_base }, - buf, - autoderef, - &including_downcast, - )?; - buf.push_str("[..]"); + } + ProjectionElem::Downcast(..) if including_downcast.0 => return None, + ProjectionElem::Downcast(..) => (), + ProjectionElem::Field(field, _ty) => { + // FIXME(project-rfc_2229#36): print capture precisely here. + if let Some(field) = self.is_upvar_field_projection(PlaceRef { + local, + projection: place.projection.split_at(index + 1).0, + }) { + buf = self.upvars[field.index()].place.to_string(self.infcx.tcx); + ok = Ok(()); + } else { + let field_name = self.describe_field( + PlaceRef { local, projection: place.projection.split_at(index).0 }, + *field, + ); + buf.push('.'); + buf.push_str(&field_name); } - }; + } + ProjectionElem::Index(index) => { + buf.push('['); + if self.append_local_to_string(*index, &mut buf).is_err() { + buf.push('_'); + } + buf.push(']'); + } + ProjectionElem::ConstantIndex { .. } | ProjectionElem::Subslice { .. } => { + // Since it isn't possible to borrow an element on a particular index and + // then use another while the borrow is held, don't output indices details + // to avoid confusing the end-user + buf.push_str("[..]"); + } } } - - Ok(()) + ok.ok().map(|_| buf) } /// Appends end-user visible description of the `local` place to `buf`. If `local` doesn't have |