Move mutability error reporting to its own file
This commit is contained in:
parent
c3dbdfee06
commit
db568e426a
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@ -16,7 +16,7 @@ use rustc::hir::def_id::DefId;
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use rustc::hir::map::definitions::DefPathData;
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use rustc::infer::InferCtxt;
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use rustc::lint::builtin::UNUSED_MUT;
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use rustc::mir::{self, AggregateKind, BasicBlock, BorrowCheckResult, BorrowKind};
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use rustc::mir::{AggregateKind, BasicBlock, BorrowCheckResult, BorrowKind};
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use rustc::mir::{ClearCrossCrate, Local, Location, Mir, Mutability, Operand, Place};
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use rustc::mir::{Field, Projection, ProjectionElem, Rvalue, Statement, StatementKind};
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use rustc::mir::{Terminator, TerminatorKind};
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@ -43,14 +43,13 @@ use dataflow::{do_dataflow, DebugFormatted};
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use dataflow::{EverInitializedPlaces, MovingOutStatements};
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use dataflow::{MaybeInitializedPlaces, MaybeUninitializedPlaces};
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use util::borrowck_errors::{BorrowckErrors, Origin};
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use util::collect_writes::FindAssignments;
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use util::suggest_ref_mut;
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use self::borrow_set::{BorrowData, BorrowSet};
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use self::flows::Flows;
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use self::location::LocationTable;
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use self::prefixes::PrefixSet;
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use self::MutateMode::{JustWrite, WriteAndRead};
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use self::mutability_errors::AccessKind;
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use self::path_utils::*;
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@ -58,12 +57,13 @@ crate mod borrow_set;
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mod error_reporting;
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mod flows;
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mod location;
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mod move_errors;
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mod mutability_errors;
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mod path_utils;
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crate mod place_ext;
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mod places_conflict;
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mod prefixes;
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mod used_muts;
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mod move_errors;
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pub(crate) mod nll;
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@ -922,7 +922,13 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
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}
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let mutability_error =
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self.check_access_permissions(place_span, rw, is_local_mutation_allowed, flow_state);
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self.check_access_permissions(
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place_span,
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rw,
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is_local_mutation_allowed,
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flow_state,
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context.loc,
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);
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let conflict_error =
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self.check_access_for_conflict(context, place_span, sd, rw, flow_state);
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@ -1668,6 +1674,7 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
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}
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}
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/// Check the permissions for the given place and read or write kind
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///
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/// Returns true if an error is reported, false otherwise.
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@ -1677,17 +1684,13 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
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kind: ReadOrWrite,
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is_local_mutation_allowed: LocalMutationIsAllowed,
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flow_state: &Flows<'cx, 'gcx, 'tcx>,
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location: Location,
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) -> bool {
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debug!(
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"check_access_permissions({:?}, {:?}, {:?})",
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place, kind, is_local_mutation_allowed
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);
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#[derive(Copy, Clone, Debug)]
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enum AccessKind {
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MutableBorrow,
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Mutate,
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}
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let error_access;
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let the_place_err;
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@ -1756,206 +1759,14 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
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}
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// at this point, we have set up the error reporting state.
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let mut err;
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let item_msg = match self.describe_place(place) {
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Some(name) => format!("immutable item `{}`", name),
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None => "immutable item".to_owned(),
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};
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// `act` and `acted_on` are strings that let us abstract over
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// the verbs used in some diagnostic messages.
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let act;
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let acted_on;
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match error_access {
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AccessKind::Mutate => {
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let item_msg = match the_place_err {
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Place::Projection(box Projection {
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base: _,
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elem: ProjectionElem::Deref,
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}) => match self.describe_place(place) {
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Some(description) => {
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format!("`{}` which is behind a `&` reference", description)
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}
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None => format!("data in a `&` reference"),
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},
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_ => item_msg,
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};
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err = self.tcx.cannot_assign(span, &item_msg, Origin::Mir);
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act = "assign";
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acted_on = "written";
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}
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AccessKind::MutableBorrow => {
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err = self
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.tcx
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.cannot_borrow_path_as_mutable(span, &item_msg, Origin::Mir);
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act = "borrow as mutable";
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acted_on = "borrowed as mutable";
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}
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}
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match the_place_err {
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// We want to suggest users use `let mut` for local (user
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// variable) mutations...
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Place::Local(local) if self.mir.local_decls[*local].can_be_made_mutable() => {
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// ... but it doesn't make sense to suggest it on
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// variables that are `ref x`, `ref mut x`, `&self`,
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// or `&mut self` (such variables are simply not
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// mutable)..
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let local_decl = &self.mir.local_decls[*local];
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assert_eq!(local_decl.mutability, Mutability::Not);
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err.span_label(span, format!("cannot {ACT}", ACT = act));
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err.span_suggestion(
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local_decl.source_info.span,
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"consider changing this to be mutable",
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format!("mut {}", local_decl.name.unwrap()),
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);
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}
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// complete hack to approximate old AST-borrowck
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// diagnostic: if the span starts with a mutable borrow of
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// a local variable, then just suggest the user remove it.
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Place::Local(_)
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if {
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if let Ok(snippet) = self.tcx.sess.codemap().span_to_snippet(span) {
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snippet.starts_with("&mut ")
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} else {
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false
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}
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} =>
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{
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err.span_label(span, format!("cannot {ACT}", ACT = act));
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err.span_label(span, "try removing `&mut` here");
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}
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// We want to point out when a `&` can be readily replaced
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// with an `&mut`.
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//
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// FIXME: can this case be generalized to work for an
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// arbitrary base for the projection?
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Place::Projection(box Projection {
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base: Place::Local(local),
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elem: ProjectionElem::Deref,
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}) if self.mir.local_decls[*local].is_user_variable.is_some() => {
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let local_decl = &self.mir.local_decls[*local];
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let suggestion = match local_decl.is_user_variable.as_ref().unwrap() {
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ClearCrossCrate::Set(mir::BindingForm::ImplicitSelf) => {
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Some(suggest_ampmut_self(local_decl))
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},
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ClearCrossCrate::Set(mir::BindingForm::Var(mir::VarBindingForm {
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binding_mode: ty::BindingMode::BindByValue(_),
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opt_ty_info,
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..
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})) => Some(suggest_ampmut(
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self.tcx,
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self.mir,
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*local,
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local_decl,
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*opt_ty_info,
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)),
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ClearCrossCrate::Set(mir::BindingForm::Var(mir::VarBindingForm {
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binding_mode: ty::BindingMode::BindByReference(_),
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..
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})) => suggest_ref_mut(self.tcx, local_decl.source_info.span),
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ClearCrossCrate::Clear => bug!("saw cleared local state"),
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};
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if let Some((err_help_span, suggested_code)) = suggestion {
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err.span_suggestion(
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err_help_span,
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"consider changing this to be a mutable reference",
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suggested_code,
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);
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}
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if let Some(name) = local_decl.name {
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err.span_label(
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span,
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format!(
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"`{NAME}` is a `&` reference, \
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so the data it refers to cannot be {ACTED_ON}",
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NAME = name,
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ACTED_ON = acted_on
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),
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);
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} else {
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err.span_label(
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span,
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format!("cannot {ACT} through `&`-reference", ACT = act),
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);
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}
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}
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_ => {
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err.span_label(span, format!("cannot {ACT}", ACT = act));
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}
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}
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err.emit();
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self.report_mutability_error(
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place,
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span,
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the_place_err,
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error_access,
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location,
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);
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return true;
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fn suggest_ampmut_self<'cx, 'gcx, 'tcx>(
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local_decl: &mir::LocalDecl<'tcx>,
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) -> (Span, String) {
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(local_decl.source_info.span, "&mut self".to_string())
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}
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// When we want to suggest a user change a local variable to be a `&mut`, there
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// are three potential "obvious" things to highlight:
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//
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// let ident [: Type] [= RightHandSideExpression];
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// ^^^^^ ^^^^ ^^^^^^^^^^^^^^^^^^^^^^^
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// (1.) (2.) (3.)
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//
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// We can always fallback on highlighting the first. But chances are good that
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// the user experience will be better if we highlight one of the others if possible;
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// for example, if the RHS is present and the Type is not, then the type is going to
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// be inferred *from* the RHS, which means we should highlight that (and suggest
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// that they borrow the RHS mutably).
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//
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// This implementation attempts to emulate AST-borrowck prioritization
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// by trying (3.), then (2.) and finally falling back on (1.).
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fn suggest_ampmut<'cx, 'gcx, 'tcx>(
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tcx: TyCtxt<'cx, 'gcx, 'tcx>,
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mir: &Mir<'tcx>,
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local: Local,
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local_decl: &mir::LocalDecl<'tcx>,
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opt_ty_info: Option<Span>,
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) -> (Span, String) {
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let locations = mir.find_assignments(local);
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if locations.len() > 0 {
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let assignment_rhs_span = mir.source_info(locations[0]).span;
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let snippet = tcx.sess.codemap().span_to_snippet(assignment_rhs_span);
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if let Ok(src) = snippet {
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if src.starts_with('&') {
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let borrowed_expr = src[1..].to_string();
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return (
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assignment_rhs_span,
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format!("&mut {}", borrowed_expr),
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);
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}
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}
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}
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let highlight_span = match opt_ty_info {
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// if this is a variable binding with an explicit type,
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// try to highlight that for the suggestion.
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Some(ty_span) => ty_span,
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// otherwise, just highlight the span associated with
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// the (MIR) LocalDecl.
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None => local_decl.source_info.span,
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};
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let ty_mut = local_decl.ty.builtin_deref(true).unwrap();
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assert_eq!(ty_mut.mutbl, hir::MutImmutable);
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(highlight_span, format!("&mut {}", ty_mut.ty))
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}
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}
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/// Adds the place into the used mutable variables set
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@ -0,0 +1,260 @@
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// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use rustc::hir;
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use rustc::mir::{self, BindingForm, ClearCrossCrate, Local, Location, Mir};
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use rustc::mir::{Mutability, Place, Projection, ProjectionElem, Static};
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use rustc::ty::{self, TyCtxt};
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use rustc_data_structures::indexed_vec::Idx;
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use syntax_pos::Span;
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use borrow_check::MirBorrowckCtxt;
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use util::borrowck_errors::{BorrowckErrors, Origin};
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use util::collect_writes::FindAssignments;
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use util::suggest_ref_mut;
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#[derive(Copy, Clone, Debug)]
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pub(super) enum AccessKind {
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MutableBorrow,
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Mutate,
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}
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impl<'a, 'gcx, 'tcx> MirBorrowckCtxt<'a, 'gcx, 'tcx> {
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pub(super) fn report_mutability_error(
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&mut self,
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access_place: &Place<'tcx>,
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span: Span,
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the_place_err: &Place<'tcx>,
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error_access: AccessKind,
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location: Location,
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) {
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let mut err;
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let item_msg = match self.describe_place(place) {
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Some(name) => format!("immutable item `{}`", name),
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None => "immutable item".to_owned(),
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};
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// `act` and `acted_on` are strings that let us abstract over
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// the verbs used in some diagnostic messages.
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let act;
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let acted_on;
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match error_access {
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AccessKind::Mutate => {
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let item_msg = match the_place_err {
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Place::Projection(box Projection {
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base: _,
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elem: ProjectionElem::Deref,
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}) => match self.describe_place(place) {
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Some(description) => {
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format!("`{}` which is behind a `&` reference", description)
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}
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None => format!("data in a `&` reference"),
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},
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_ => item_msg,
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};
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err = self.tcx.cannot_assign(span, &item_msg, Origin::Mir);
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act = "assign";
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acted_on = "written";
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}
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AccessKind::MutableBorrow => {
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err = self
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.tcx
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.cannot_borrow_path_as_mutable(span, &item_msg, Origin::Mir);
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act = "borrow as mutable";
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acted_on = "borrowed as mutable";
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}
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}
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|
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match the_place_err {
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// We want to suggest users use `let mut` for local (user
|
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// variable) mutations...
|
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Place::Local(local) if self.mir.local_decls[*local].can_be_made_mutable() => {
|
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// ... but it doesn't make sense to suggest it on
|
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// variables that are `ref x`, `ref mut x`, `&self`,
|
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// or `&mut self` (such variables are simply not
|
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// mutable)..
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let local_decl = &self.mir.local_decls[*local];
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assert_eq!(local_decl.mutability, Mutability::Not);
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err.span_label(span, format!("cannot {ACT}", ACT = act));
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err.span_suggestion(
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local_decl.source_info.span,
|
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"consider changing this to be mutable",
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format!("mut {}", local_decl.name.unwrap()),
|
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);
|
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}
|
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|
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// complete hack to approximate old AST-borrowck
|
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// diagnostic: if the span starts with a mutable borrow of
|
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// a local variable, then just suggest the user remove it.
|
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Place::Local(_)
|
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if {
|
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if let Ok(snippet) = self.tcx.sess.codemap().span_to_snippet(span) {
|
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snippet.starts_with("&mut ")
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} else {
|
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false
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}
|
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} =>
|
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{
|
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err.span_label(span, format!("cannot {ACT}", ACT = act));
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err.span_label(span, "try removing `&mut` here");
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}
|
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|
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// We want to point out when a `&` can be readily replaced
|
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// with an `&mut`.
|
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//
|
||||
// FIXME: can this case be generalized to work for an
|
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// arbitrary base for the projection?
|
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Place::Projection(box Projection {
|
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base: Place::Local(local),
|
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elem: ProjectionElem::Deref,
|
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}) if self.mir.local_decls[*local].is_user_variable.is_some() => {
|
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let local_decl = &self.mir.local_decls[*local];
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let suggestion = match local_decl.is_user_variable.as_ref().unwrap() {
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ClearCrossCrate::Set(mir::BindingForm::ImplicitSelf) => {
|
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Some(suggest_ampmut_self(local_decl))
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},
|
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|
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ClearCrossCrate::Set(mir::BindingForm::Var(mir::VarBindingForm {
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binding_mode: ty::BindingMode::BindByValue(_),
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opt_ty_info,
|
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..
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})) => Some(suggest_ampmut(
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self.tcx,
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self.mir,
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*local,
|
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local_decl,
|
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*opt_ty_info,
|
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)),
|
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|
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ClearCrossCrate::Set(mir::BindingForm::Var(mir::VarBindingForm {
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binding_mode: ty::BindingMode::BindByReference(_),
|
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..
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})) => suggest_ref_mut(self.tcx, local_decl.source_info.span),
|
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|
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ClearCrossCrate::Clear => bug!("saw cleared local state"),
|
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};
|
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|
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if let Some((err_help_span, suggested_code)) = suggestion {
|
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err.span_suggestion(
|
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err_help_span,
|
||||
"consider changing this to be a mutable reference",
|
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suggested_code,
|
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);
|
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}
|
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|
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if let Some(name) = local_decl.name {
|
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err.span_label(
|
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span,
|
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format!(
|
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"`{NAME}` is a `&` reference, \
|
||||
so the data it refers to cannot be {ACTED_ON}",
|
||||
NAME = name,
|
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ACTED_ON = acted_on
|
||||
),
|
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);
|
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} else {
|
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err.span_label(
|
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span,
|
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format!("cannot {ACT} through `&`-reference", ACT = act),
|
||||
);
|
||||
}
|
||||
}
|
||||
|
||||
_ => {
|
||||
err.span_label(span, format!("cannot {ACT}", ACT = act));
|
||||
}
|
||||
}
|
||||
|
||||
err.emit();
|
||||
}
|
||||
|
||||
// Does this place refer to what the user sees as an upvar
|
||||
fn is_upvar(&self, place: &Place<'tcx>) -> bool {
|
||||
match *place {
|
||||
Place::Projection(box Projection {
|
||||
ref base,
|
||||
elem: ProjectionElem::Field(_, _),
|
||||
}) => {
|
||||
let base_ty = base.ty(self.mir, self.tcx).to_ty(self.tcx);
|
||||
is_closure_or_generator(base_ty)
|
||||
}
|
||||
Place::Projection(box Projection {
|
||||
base:
|
||||
Place::Projection(box Projection {
|
||||
ref base,
|
||||
elem: ProjectionElem::Field(upvar_index, _),
|
||||
}),
|
||||
elem: ProjectionElem::Deref,
|
||||
}) => {
|
||||
let base_ty = base.ty(self.mir, self.tcx).to_ty(self.tcx);
|
||||
is_closure_or_generator(base_ty) && self.mir.upvar_decls[upvar_index.index()].by_ref
|
||||
}
|
||||
_ => false,
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn suggest_ampmut_self<'cx, 'gcx, 'tcx>(local_decl: &mir::LocalDecl<'tcx>) -> (Span, String) {
|
||||
(local_decl.source_info.span, "&mut self".to_string())
|
||||
}
|
||||
|
||||
// When we want to suggest a user change a local variable to be a `&mut`, there
|
||||
// are three potential "obvious" things to highlight:
|
||||
//
|
||||
// let ident [: Type] [= RightHandSideExpression];
|
||||
// ^^^^^ ^^^^ ^^^^^^^^^^^^^^^^^^^^^^^
|
||||
// (1.) (2.) (3.)
|
||||
//
|
||||
// We can always fallback on highlighting the first. But chances are good that
|
||||
// the user experience will be better if we highlight one of the others if possible;
|
||||
// for example, if the RHS is present and the Type is not, then the type is going to
|
||||
// be inferred *from* the RHS, which means we should highlight that (and suggest
|
||||
// that they borrow the RHS mutably).
|
||||
//
|
||||
// This implementation attempts to emulate AST-borrowck prioritization
|
||||
// by trying (3.), then (2.) and finally falling back on (1.).
|
||||
fn suggest_ampmut<'cx, 'gcx, 'tcx>(
|
||||
tcx: TyCtxt<'cx, 'gcx, 'tcx>,
|
||||
mir: &Mir<'tcx>,
|
||||
local: Local,
|
||||
local_decl: &mir::LocalDecl<'tcx>,
|
||||
opt_ty_info: Option<Span>,
|
||||
) -> (Span, String) {
|
||||
let locations = mir.find_assignments(local);
|
||||
if locations.len() > 0 {
|
||||
let assignment_rhs_span = mir.source_info(locations[0]).span;
|
||||
let snippet = tcx.sess.codemap().span_to_snippet(assignment_rhs_span);
|
||||
if let Ok(src) = snippet {
|
||||
if src.starts_with('&') {
|
||||
let borrowed_expr = src[1..].to_string();
|
||||
return (
|
||||
assignment_rhs_span,
|
||||
format!("&mut {}", borrowed_expr),
|
||||
);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
let highlight_span = match opt_ty_info {
|
||||
// if this is a variable binding with an explicit type,
|
||||
// try to highlight that for the suggestion.
|
||||
Some(ty_span) => ty_span,
|
||||
|
||||
// otherwise, just highlight the span associated with
|
||||
// the (MIR) LocalDecl.
|
||||
None => local_decl.source_info.span,
|
||||
};
|
||||
|
||||
let ty_mut = local_decl.ty.builtin_deref(true).unwrap();
|
||||
assert_eq!(ty_mut.mutbl, hir::MutImmutable);
|
||||
(highlight_span, format!("&mut {}", ty_mut.ty))
|
||||
}
|
Loading…
Reference in New Issue