diff options
Diffstat (limited to 'compiler/rustc_borrowck/src/diagnostics/region_errors.rs')
| -rw-r--r-- | compiler/rustc_borrowck/src/diagnostics/region_errors.rs | 156 |
1 files changed, 99 insertions, 57 deletions
diff --git a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs index 176090c3b..34be2874f 100644 --- a/compiler/rustc_borrowck/src/diagnostics/region_errors.rs +++ b/compiler/rustc_borrowck/src/diagnostics/region_errors.rs @@ -1,3 +1,5 @@ +#![deny(rustc::untranslatable_diagnostic)] +#![deny(rustc::diagnostic_outside_of_impl)] //! Error reporting machinery for lifetime errors. use rustc_data_structures::fx::FxHashSet; @@ -23,10 +25,13 @@ use rustc_span::symbol::{kw, sym, Ident}; use rustc_span::Span; use crate::borrowck_errors; -use crate::session_diagnostics::GenericDoesNotLiveLongEnough; +use crate::session_diagnostics::{ + FnMutError, FnMutReturnTypeErr, GenericDoesNotLiveLongEnough, LifetimeOutliveErr, + LifetimeReturnCategoryErr, RequireStaticErr, VarHereDenote, +}; use super::{OutlivesSuggestionBuilder, RegionName}; -use crate::region_infer::BlameConstraint; +use crate::region_infer::{BlameConstraint, ExtraConstraintInfo}; use crate::{ nll::ConstraintDescription, region_infer::{values::RegionElement, TypeTest}, @@ -229,7 +234,6 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { // Find the code to blame for the fact that `longer_fr` outlives `error_fr`. let (_, cause) = self.regioncx.find_outlives_blame_span( - &self.body, longer_fr, NllRegionVariableOrigin::Placeholder(placeholder), error_vid, @@ -350,10 +354,11 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { ) { debug!("report_region_error(fr={:?}, outlived_fr={:?})", fr, outlived_fr); - let BlameConstraint { category, cause, variance_info, from_closure: _ } = - self.regioncx.best_blame_constraint(&self.body, fr, fr_origin, |r| { + let (blame_constraint, extra_info) = + self.regioncx.best_blame_constraint(fr, fr_origin, |r| { self.regioncx.provides_universal_region(r, fr, outlived_fr) }); + let BlameConstraint { category, cause, variance_info, .. } = blame_constraint; debug!("report_region_error: category={:?} {:?} {:?}", category, cause, variance_info); @@ -462,6 +467,14 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { } } + for extra in extra_info { + match extra { + ExtraConstraintInfo::PlaceholderFromPredicate(span) => { + diag.span_note(span, format!("due to current limitations in the borrow checker, this implies a `'static` lifetime")); + } + } + } + self.buffer_error(diag); } @@ -488,12 +501,6 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { ) -> DiagnosticBuilder<'tcx, ErrorGuaranteed> { let ErrorConstraintInfo { outlived_fr, span, .. } = errci; - let mut diag = self - .infcx - .tcx - .sess - .struct_span_err(*span, "captured variable cannot escape `FnMut` closure body"); - let mut output_ty = self.regioncx.universal_regions().unnormalized_output_ty; if let ty::Opaque(def_id, _) = *output_ty.kind() { output_ty = self.infcx.tcx.type_of(def_id) @@ -501,19 +508,20 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { debug!("report_fnmut_error: output_ty={:?}", output_ty); - let message = match output_ty.kind() { - ty::Closure(_, _) => { - "returns a closure that contains a reference to a captured variable, which then \ - escapes the closure body" - } - ty::Adt(def, _) if self.infcx.tcx.is_diagnostic_item(sym::gen_future, def.did()) => { - "returns an `async` block that contains a reference to a captured variable, which then \ - escapes the closure body" - } - _ => "returns a reference to a captured variable which escapes the closure body", + let err = FnMutError { + span: *span, + ty_err: match output_ty.kind() { + ty::Closure(_, _) => FnMutReturnTypeErr::ReturnClosure { span: *span }, + ty::Adt(def, _) + if self.infcx.tcx.is_diagnostic_item(sym::gen_future, def.did()) => + { + FnMutReturnTypeErr::ReturnAsyncBlock { span: *span } + } + _ => FnMutReturnTypeErr::ReturnRef { span: *span }, + }, }; - diag.span_label(*span, message); + let mut diag = self.infcx.tcx.sess.create_err(err); if let ReturnConstraint::ClosureUpvar(upvar_field) = kind { let def_id = match self.regioncx.universal_regions().defining_ty { @@ -532,20 +540,16 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { let upvars_map = self.infcx.tcx.upvars_mentioned(def_id).unwrap(); let upvar_def_span = self.infcx.tcx.hir().span(def_hir); let upvar_span = upvars_map.get(&def_hir).unwrap().span; - diag.span_label(upvar_def_span, "variable defined here"); - diag.span_label(upvar_span, "variable captured here"); + diag.subdiagnostic(VarHereDenote::Defined { span: upvar_def_span }); + diag.subdiagnostic(VarHereDenote::Captured { span: upvar_span }); } } if let Some(fr_span) = self.give_region_a_name(*outlived_fr).unwrap().span() { - diag.span_label(fr_span, "inferred to be a `FnMut` closure"); + diag.subdiagnostic(VarHereDenote::FnMutInferred { span: fr_span }); } - diag.note( - "`FnMut` closures only have access to their captured variables while they are \ - executing...", - ); - diag.note("...therefore, they cannot allow references to captured variables to escape"); + self.suggest_move_on_borrowing_closure(&mut diag); diag } @@ -562,6 +566,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { /// LL | ref_obj(x) /// | ^^^^^^^^^^ `x` escapes the function body here /// ``` + #[instrument(level = "debug", skip(self))] fn report_escaping_data_error( &self, errci: &ErrorConstraintInfo<'tcx>, @@ -680,42 +685,37 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { .. } = errci; - let mut diag = - self.infcx.tcx.sess.struct_span_err(*span, "lifetime may not live long enough"); - let (_, mir_def_name) = self.infcx.tcx.article_and_description(self.mir_def_id().to_def_id()); + let err = LifetimeOutliveErr { span: *span }; + let mut diag = self.infcx.tcx.sess.create_err(err); + let fr_name = self.give_region_a_name(*fr).unwrap(); fr_name.highlight_region_name(&mut diag); let outlived_fr_name = self.give_region_a_name(*outlived_fr).unwrap(); outlived_fr_name.highlight_region_name(&mut diag); - match (category, outlived_fr_is_local, fr_is_local) { - (ConstraintCategory::Return(_), true, _) => { - diag.span_label( - *span, - format!( - "{mir_def_name} was supposed to return data with lifetime `{outlived_fr_name}` but it is returning \ - data with lifetime `{fr_name}`", - ), - ); - } - _ => { - diag.span_label( - *span, - format!( - "{}requires that `{}` must outlive `{}`", - category.description(), - fr_name, - outlived_fr_name, - ), - ); - } - } + let err_category = match (category, outlived_fr_is_local, fr_is_local) { + (ConstraintCategory::Return(_), true, _) => LifetimeReturnCategoryErr::WrongReturn { + span: *span, + mir_def_name, + outlived_fr_name, + fr_name: &fr_name, + }, + _ => LifetimeReturnCategoryErr::ShortReturn { + span: *span, + category_desc: category.description(), + free_region_name: &fr_name, + outlived_fr_name, + }, + }; + + diag.subdiagnostic(err_category); self.add_static_impl_trait_suggestion(&mut diag, *fr, fr_name, *outlived_fr); self.suggest_adding_lifetime_params(&mut diag, *fr, *outlived_fr); + self.suggest_move_on_borrowing_closure(&mut diag); diag } @@ -783,7 +783,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { fn maybe_suggest_constrain_dyn_trait_impl( &self, - diag: &mut DiagnosticBuilder<'tcx, ErrorGuaranteed>, + diag: &mut Diagnostic, f: Region<'tcx>, o: Region<'tcx>, category: &ConstraintCategory<'tcx>, @@ -860,7 +860,7 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { ident.span, "calling this method introduces the `impl`'s 'static` requirement", ); - err.span_note(multi_span, "the used `impl` has a `'static` requirement"); + err.subdiagnostic(RequireStaticErr::UsedImpl { multi_span }); err.span_suggestion_verbose( span.shrink_to_hi(), "consider relaxing the implicit `'static` requirement", @@ -901,4 +901,46 @@ impl<'a, 'tcx> MirBorrowckCtxt<'a, 'tcx> { suggest_adding_lifetime_params(self.infcx.tcx, sub, ty_sup, ty_sub, diag); } + + fn suggest_move_on_borrowing_closure(&self, diag: &mut Diagnostic) { + let map = self.infcx.tcx.hir(); + let body_id = map.body_owned_by(self.mir_def_id()); + let expr = &map.body(body_id).value; + let mut closure_span = None::<rustc_span::Span>; + match expr.kind { + hir::ExprKind::MethodCall(.., args, _) => { + for arg in args { + if let hir::ExprKind::Closure(hir::Closure { + capture_clause: hir::CaptureBy::Ref, + .. + }) = arg.kind + { + closure_span = Some(arg.span.shrink_to_lo()); + break; + } + } + } + hir::ExprKind::Block(blk, _) => { + if let Some(ref expr) = blk.expr { + // only when the block is a closure + if let hir::ExprKind::Closure(hir::Closure { + capture_clause: hir::CaptureBy::Ref, + .. + }) = expr.kind + { + closure_span = Some(expr.span.shrink_to_lo()); + } + } + } + _ => {} + } + if let Some(closure_span) = closure_span { + diag.span_suggestion_verbose( + closure_span, + "consider adding 'move' keyword before the nested closure", + "move ", + Applicability::MaybeIncorrect, + ); + } + } } |