| use std::fmt::{self, Display}; |
| use std::iter; |
| |
| use rustc_errors::Diagnostic; |
| use rustc_hir as hir; |
| use rustc_hir::def::{DefKind, Res}; |
| use rustc_middle::ty::print::RegionHighlightMode; |
| use rustc_middle::ty::subst::{GenericArgKind, SubstsRef}; |
| use rustc_middle::ty::{self, RegionVid, Ty}; |
| use rustc_span::symbol::{kw, sym, Ident, Symbol}; |
| use rustc_span::{Span, DUMMY_SP}; |
| |
| use crate::{universal_regions::DefiningTy, MirBorrowckCtxt}; |
| |
| /// A name for a particular region used in emitting diagnostics. This name could be a generated |
| /// name like `'1`, a name used by the user like `'a`, or a name like `'static`. |
| #[derive(Debug, Clone)] |
| pub(crate) struct RegionName { |
| /// The name of the region (interned). |
| pub(crate) name: Symbol, |
| /// Where the region comes from. |
| pub(crate) source: RegionNameSource, |
| } |
| |
| /// Denotes the source of a region that is named by a `RegionName`. For example, a free region that |
| /// was named by the user would get `NamedFreeRegion` and `'static` lifetime would get `Static`. |
| /// This helps to print the right kinds of diagnostics. |
| #[derive(Debug, Clone)] |
| pub(crate) enum RegionNameSource { |
| /// A bound (not free) region that was substituted at the def site (not an HRTB). |
| NamedEarlyBoundRegion(Span), |
| /// A free region that the user has a name (`'a`) for. |
| NamedFreeRegion(Span), |
| /// The `'static` region. |
| Static, |
| /// The free region corresponding to the environment of a closure. |
| SynthesizedFreeEnvRegion(Span, &'static str), |
| /// The region corresponding to an argument. |
| AnonRegionFromArgument(RegionNameHighlight), |
| /// The region corresponding to a closure upvar. |
| AnonRegionFromUpvar(Span, Symbol), |
| /// The region corresponding to the return type of a closure. |
| AnonRegionFromOutput(RegionNameHighlight, &'static str), |
| /// The region from a type yielded by a generator. |
| AnonRegionFromYieldTy(Span, String), |
| /// An anonymous region from an async fn. |
| AnonRegionFromAsyncFn(Span), |
| /// An anonymous region from an impl self type or trait |
| AnonRegionFromImplSignature(Span, &'static str), |
| } |
| |
| /// Describes what to highlight to explain to the user that we're giving an anonymous region a |
| /// synthesized name, and how to highlight it. |
| #[derive(Debug, Clone)] |
| pub(crate) enum RegionNameHighlight { |
| /// The anonymous region corresponds to a reference that was found by traversing the type in the HIR. |
| MatchedHirTy(Span), |
| /// The anonymous region corresponds to a `'_` in the generics list of a struct/enum/union. |
| MatchedAdtAndSegment(Span), |
| /// The anonymous region corresponds to a region where the type annotation is completely missing |
| /// from the code, e.g. in a closure arguments `|x| { ... }`, where `x` is a reference. |
| CannotMatchHirTy(Span, String), |
| /// The anonymous region corresponds to a region where the type annotation is completely missing |
| /// from the code, and *even if* we print out the full name of the type, the region name won't |
| /// be included. This currently occurs for opaque types like `impl Future`. |
| Occluded(Span, String), |
| } |
| |
| impl RegionName { |
| pub(crate) fn was_named(&self) -> bool { |
| match self.source { |
| RegionNameSource::NamedEarlyBoundRegion(..) |
| | RegionNameSource::NamedFreeRegion(..) |
| | RegionNameSource::Static => true, |
| RegionNameSource::SynthesizedFreeEnvRegion(..) |
| | RegionNameSource::AnonRegionFromArgument(..) |
| | RegionNameSource::AnonRegionFromUpvar(..) |
| | RegionNameSource::AnonRegionFromOutput(..) |
| | RegionNameSource::AnonRegionFromYieldTy(..) |
| | RegionNameSource::AnonRegionFromAsyncFn(..) |
| | RegionNameSource::AnonRegionFromImplSignature(..) => false, |
| } |
| } |
| |
| pub(crate) fn span(&self) -> Option<Span> { |
| match self.source { |
| RegionNameSource::Static => None, |
| RegionNameSource::NamedEarlyBoundRegion(span) |
| | RegionNameSource::NamedFreeRegion(span) |
| | RegionNameSource::SynthesizedFreeEnvRegion(span, _) |
| | RegionNameSource::AnonRegionFromUpvar(span, _) |
| | RegionNameSource::AnonRegionFromYieldTy(span, _) |
| | RegionNameSource::AnonRegionFromAsyncFn(span) |
| | RegionNameSource::AnonRegionFromImplSignature(span, _) => Some(span), |
| RegionNameSource::AnonRegionFromArgument(ref highlight) |
| | RegionNameSource::AnonRegionFromOutput(ref highlight, _) => match *highlight { |
| RegionNameHighlight::MatchedHirTy(span) |
| | RegionNameHighlight::MatchedAdtAndSegment(span) |
| | RegionNameHighlight::CannotMatchHirTy(span, _) |
| | RegionNameHighlight::Occluded(span, _) => Some(span), |
| }, |
| } |
| } |
| |
| pub(crate) fn highlight_region_name(&self, diag: &mut Diagnostic) { |
| match &self.source { |
| RegionNameSource::NamedFreeRegion(span) |
| | RegionNameSource::NamedEarlyBoundRegion(span) => { |
| diag.span_label(*span, format!("lifetime `{self}` defined here")); |
| } |
| RegionNameSource::SynthesizedFreeEnvRegion(span, note) => { |
| diag.span_label(*span, format!("lifetime `{self}` represents this closure's body")); |
| diag.note(*note); |
| } |
| RegionNameSource::AnonRegionFromArgument(RegionNameHighlight::CannotMatchHirTy( |
| span, |
| type_name, |
| )) => { |
| diag.span_label(*span, format!("has type `{type_name}`")); |
| } |
| RegionNameSource::AnonRegionFromArgument(RegionNameHighlight::MatchedHirTy(span)) |
| | RegionNameSource::AnonRegionFromOutput(RegionNameHighlight::MatchedHirTy(span), _) |
| | RegionNameSource::AnonRegionFromAsyncFn(span) => { |
| diag.span_label( |
| *span, |
| format!("let's call the lifetime of this reference `{self}`"), |
| ); |
| } |
| RegionNameSource::AnonRegionFromArgument( |
| RegionNameHighlight::MatchedAdtAndSegment(span), |
| ) |
| | RegionNameSource::AnonRegionFromOutput( |
| RegionNameHighlight::MatchedAdtAndSegment(span), |
| _, |
| ) => { |
| diag.span_label(*span, format!("let's call this `{self}`")); |
| } |
| RegionNameSource::AnonRegionFromArgument(RegionNameHighlight::Occluded( |
| span, |
| type_name, |
| )) => { |
| diag.span_label( |
| *span, |
| format!("lifetime `{self}` appears in the type {type_name}"), |
| ); |
| } |
| RegionNameSource::AnonRegionFromOutput( |
| RegionNameHighlight::Occluded(span, type_name), |
| mir_description, |
| ) => { |
| diag.span_label( |
| *span, |
| format!( |
| "return type{mir_description} `{type_name}` contains a lifetime `{self}`" |
| ), |
| ); |
| } |
| RegionNameSource::AnonRegionFromUpvar(span, upvar_name) => { |
| diag.span_label( |
| *span, |
| format!("lifetime `{self}` appears in the type of `{upvar_name}`"), |
| ); |
| } |
| RegionNameSource::AnonRegionFromOutput( |
| RegionNameHighlight::CannotMatchHirTy(span, type_name), |
| mir_description, |
| ) => { |
| diag.span_label(*span, format!("return type{mir_description} is {type_name}")); |
| } |
| RegionNameSource::AnonRegionFromYieldTy(span, type_name) => { |
| diag.span_label(*span, format!("yield type is {type_name}")); |
| } |
| RegionNameSource::AnonRegionFromImplSignature(span, location) => { |
| diag.span_label( |
| *span, |
| format!("lifetime `{self}` appears in the `impl`'s {location}"), |
| ); |
| } |
| RegionNameSource::Static => {} |
| } |
| } |
| } |
| |
| impl Display for RegionName { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| write!(f, "{}", self.name) |
| } |
| } |
| |
| impl rustc_errors::IntoDiagnosticArg for RegionName { |
| fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> { |
| self.to_string().into_diagnostic_arg() |
| } |
| } |
| |
| impl<'tcx> MirBorrowckCtxt<'_, 'tcx> { |
| pub(crate) fn mir_def_id(&self) -> hir::def_id::LocalDefId { |
| self.body.source.def_id().expect_local() |
| } |
| |
| pub(crate) fn mir_hir_id(&self) -> hir::HirId { |
| self.infcx.tcx.hir().local_def_id_to_hir_id(self.mir_def_id()) |
| } |
| |
| /// Generate a synthetic region named `'N`, where `N` is the next value of the counter. Then, |
| /// increment the counter. |
| /// |
| /// This is _not_ idempotent. Call `give_region_a_name` when possible. |
| pub(crate) fn synthesize_region_name(&self) -> Symbol { |
| let c = self.next_region_name.replace_with(|counter| *counter + 1); |
| Symbol::intern(&format!("'{c:?}")) |
| } |
| |
| /// Maps from an internal MIR region vid to something that we can |
| /// report to the user. In some cases, the region vids will map |
| /// directly to lifetimes that the user has a name for (e.g., |
| /// `'static`). But frequently they will not, in which case we |
| /// have to find some way to identify the lifetime to the user. To |
| /// that end, this function takes a "diagnostic" so that it can |
| /// create auxiliary notes as needed. |
| /// |
| /// The names are memoized, so this is both cheap to recompute and idempotent. |
| /// |
| /// Example (function arguments): |
| /// |
| /// Suppose we are trying to give a name to the lifetime of the |
| /// reference `x`: |
| /// |
| /// ```ignore (pseudo-rust) |
| /// fn foo(x: &u32) { .. } |
| /// ``` |
| /// |
| /// This function would create a label like this: |
| /// |
| /// ```text |
| /// | fn foo(x: &u32) { .. } |
| /// ------- fully elaborated type of `x` is `&'1 u32` |
| /// ``` |
| /// |
| /// and then return the name `'1` for us to use. |
| pub(crate) fn give_region_a_name(&self, fr: RegionVid) -> Option<RegionName> { |
| debug!( |
| "give_region_a_name(fr={:?}, counter={:?})", |
| fr, |
| self.next_region_name.try_borrow().unwrap() |
| ); |
| |
| assert!(self.regioncx.universal_regions().is_universal_region(fr)); |
| |
| if let Some(value) = self.region_names.try_borrow_mut().unwrap().get(&fr) { |
| return Some(value.clone()); |
| } |
| |
| let value = self |
| .give_name_from_error_region(fr) |
| .or_else(|| self.give_name_if_anonymous_region_appears_in_arguments(fr)) |
| .or_else(|| self.give_name_if_anonymous_region_appears_in_upvars(fr)) |
| .or_else(|| self.give_name_if_anonymous_region_appears_in_output(fr)) |
| .or_else(|| self.give_name_if_anonymous_region_appears_in_yield_ty(fr)) |
| .or_else(|| self.give_name_if_anonymous_region_appears_in_impl_signature(fr)) |
| .or_else(|| self.give_name_if_anonymous_region_appears_in_arg_position_impl_trait(fr)); |
| |
| if let Some(value) = &value { |
| self.region_names.try_borrow_mut().unwrap().insert(fr, value.clone()); |
| } |
| |
| debug!("give_region_a_name: gave name {:?}", value); |
| value |
| } |
| |
| /// Checks for the case where `fr` maps to something that the |
| /// *user* has a name for. In that case, we'll be able to map |
| /// `fr` to a `Region<'tcx>`, and that region will be one of |
| /// named variants. |
| #[instrument(level = "trace", skip(self))] |
| fn give_name_from_error_region(&self, fr: RegionVid) -> Option<RegionName> { |
| let error_region = self.to_error_region(fr)?; |
| |
| let tcx = self.infcx.tcx; |
| |
| debug!("give_region_a_name: error_region = {:?}", error_region); |
| match *error_region { |
| ty::ReEarlyBound(ebr) => ebr.has_name().then(|| { |
| let span = tcx.hir().span_if_local(ebr.def_id).unwrap_or(DUMMY_SP); |
| RegionName { name: ebr.name, source: RegionNameSource::NamedEarlyBoundRegion(span) } |
| }), |
| |
| ty::ReStatic => { |
| Some(RegionName { name: kw::StaticLifetime, source: RegionNameSource::Static }) |
| } |
| |
| ty::ReFree(free_region) => match free_region.bound_region { |
| ty::BoundRegionKind::BrNamed(region_def_id, name) => { |
| // Get the span to point to, even if we don't use the name. |
| let span = tcx.hir().span_if_local(region_def_id).unwrap_or(DUMMY_SP); |
| debug!( |
| "bound region named: {:?}, is_named: {:?}", |
| name, |
| free_region.bound_region.is_named() |
| ); |
| |
| if free_region.bound_region.is_named() { |
| // A named region that is actually named. |
| Some(RegionName { name, source: RegionNameSource::NamedFreeRegion(span) }) |
| } else if let hir::IsAsync::Async = tcx.asyncness(self.mir_hir_id().owner) { |
| // If we spuriously thought that the region is named, we should let the |
| // system generate a true name for error messages. Currently this can |
| // happen if we have an elided name in an async fn for example: the |
| // compiler will generate a region named `'_`, but reporting such a name is |
| // not actually useful, so we synthesize a name for it instead. |
| let name = self.synthesize_region_name(); |
| Some(RegionName { |
| name, |
| source: RegionNameSource::AnonRegionFromAsyncFn(span), |
| }) |
| } else { |
| None |
| } |
| } |
| |
| ty::BoundRegionKind::BrEnv => { |
| let def_ty = self.regioncx.universal_regions().defining_ty; |
| |
| let DefiningTy::Closure(_, substs) = def_ty else { |
| // Can't have BrEnv in functions, constants or generators. |
| bug!("BrEnv outside of closure."); |
| }; |
| let hir::ExprKind::Closure(&hir::Closure { fn_decl_span, .. }) |
| = tcx.hir().expect_expr(self.mir_hir_id()).kind |
| else { |
| bug!("Closure is not defined by a closure expr"); |
| }; |
| let region_name = self.synthesize_region_name(); |
| |
| let closure_kind_ty = substs.as_closure().kind_ty(); |
| let note = match closure_kind_ty.to_opt_closure_kind() { |
| Some(ty::ClosureKind::Fn) => { |
| "closure implements `Fn`, so references to captured variables \ |
| can't escape the closure" |
| } |
| Some(ty::ClosureKind::FnMut) => { |
| "closure implements `FnMut`, so references to captured variables \ |
| can't escape the closure" |
| } |
| Some(ty::ClosureKind::FnOnce) => { |
| bug!("BrEnv in a `FnOnce` closure"); |
| } |
| None => bug!("Closure kind not inferred in borrow check"), |
| }; |
| |
| Some(RegionName { |
| name: region_name, |
| source: RegionNameSource::SynthesizedFreeEnvRegion(fn_decl_span, note), |
| }) |
| } |
| |
| ty::BoundRegionKind::BrAnon(..) => None, |
| }, |
| |
| ty::ReLateBound(..) |
| | ty::ReVar(..) |
| | ty::RePlaceholder(..) |
| | ty::ReErased |
| | ty::ReError(_) => None, |
| } |
| } |
| |
| /// Finds an argument that contains `fr` and label it with a fully |
| /// elaborated type, returning something like `'1`. Result looks |
| /// like: |
| /// |
| /// ```text |
| /// | fn foo(x: &u32) { .. } |
| /// ------- fully elaborated type of `x` is `&'1 u32` |
| /// ``` |
| #[instrument(level = "trace", skip(self))] |
| fn give_name_if_anonymous_region_appears_in_arguments( |
| &self, |
| fr: RegionVid, |
| ) -> Option<RegionName> { |
| let implicit_inputs = self.regioncx.universal_regions().defining_ty.implicit_inputs(); |
| let argument_index = self.regioncx.get_argument_index_for_region(self.infcx.tcx, fr)?; |
| |
| let arg_ty = self.regioncx.universal_regions().unnormalized_input_tys |
| [implicit_inputs + argument_index]; |
| let (_, span) = self.regioncx.get_argument_name_and_span_for_region( |
| &self.body, |
| &self.local_names, |
| argument_index, |
| ); |
| |
| let highlight = self |
| .get_argument_hir_ty_for_highlighting(argument_index) |
| .and_then(|arg_hir_ty| self.highlight_if_we_can_match_hir_ty(fr, arg_ty, arg_hir_ty)) |
| .unwrap_or_else(|| { |
| // `highlight_if_we_cannot_match_hir_ty` needs to know the number we will give to |
| // the anonymous region. If it succeeds, the `synthesize_region_name` call below |
| // will increment the counter, "reserving" the number we just used. |
| let counter = *self.next_region_name.try_borrow().unwrap(); |
| self.highlight_if_we_cannot_match_hir_ty(fr, arg_ty, span, counter) |
| }); |
| |
| Some(RegionName { |
| name: self.synthesize_region_name(), |
| source: RegionNameSource::AnonRegionFromArgument(highlight), |
| }) |
| } |
| |
| fn get_argument_hir_ty_for_highlighting( |
| &self, |
| argument_index: usize, |
| ) -> Option<&hir::Ty<'tcx>> { |
| let fn_decl = self.infcx.tcx.hir().fn_decl_by_hir_id(self.mir_hir_id())?; |
| let argument_hir_ty: &hir::Ty<'_> = fn_decl.inputs.get(argument_index)?; |
| match argument_hir_ty.kind { |
| // This indicates a variable with no type annotation, like |
| // `|x|`... in that case, we can't highlight the type but |
| // must highlight the variable. |
| // NOTE(eddyb) this is handled in/by the sole caller |
| // (`give_name_if_anonymous_region_appears_in_arguments`). |
| hir::TyKind::Infer => None, |
| |
| _ => Some(argument_hir_ty), |
| } |
| } |
| |
| /// Attempts to highlight the specific part of a type in an argument |
| /// that has no type annotation. |
| /// For example, we might produce an annotation like this: |
| /// |
| /// ```text |
| /// | foo(|a, b| b) |
| /// | - - |
| /// | | | |
| /// | | has type `&'1 u32` |
| /// | has type `&'2 u32` |
| /// ``` |
| fn highlight_if_we_cannot_match_hir_ty( |
| &self, |
| needle_fr: RegionVid, |
| ty: Ty<'tcx>, |
| span: Span, |
| counter: usize, |
| ) -> RegionNameHighlight { |
| let mut highlight = RegionHighlightMode::new(self.infcx.tcx); |
| highlight.highlighting_region_vid(needle_fr, counter); |
| let type_name = |
| self.infcx.extract_inference_diagnostics_data(ty.into(), Some(highlight)).name; |
| |
| debug!( |
| "highlight_if_we_cannot_match_hir_ty: type_name={:?} needle_fr={:?}", |
| type_name, needle_fr |
| ); |
| if type_name.contains(&format!("'{counter}")) { |
| // Only add a label if we can confirm that a region was labelled. |
| RegionNameHighlight::CannotMatchHirTy(span, type_name) |
| } else { |
| RegionNameHighlight::Occluded(span, type_name) |
| } |
| } |
| |
| /// Attempts to highlight the specific part of a type annotation |
| /// that contains the anonymous reference we want to give a name |
| /// to. For example, we might produce an annotation like this: |
| /// |
| /// ```text |
| /// | fn a<T>(items: &[T]) -> Box<dyn Iterator<Item = &T>> { |
| /// | - let's call the lifetime of this reference `'1` |
| /// ``` |
| /// |
| /// the way this works is that we match up `ty`, which is |
| /// a `Ty<'tcx>` (the internal form of the type) with |
| /// `hir_ty`, a `hir::Ty` (the syntax of the type |
| /// annotation). We are descending through the types stepwise, |
| /// looking in to find the region `needle_fr` in the internal |
| /// type. Once we find that, we can use the span of the `hir::Ty` |
| /// to add the highlight. |
| /// |
| /// This is a somewhat imperfect process, so along the way we also |
| /// keep track of the **closest** type we've found. If we fail to |
| /// find the exact `&` or `'_` to highlight, then we may fall back |
| /// to highlighting that closest type instead. |
| fn highlight_if_we_can_match_hir_ty( |
| &self, |
| needle_fr: RegionVid, |
| ty: Ty<'tcx>, |
| hir_ty: &hir::Ty<'_>, |
| ) -> Option<RegionNameHighlight> { |
| let search_stack: &mut Vec<(Ty<'tcx>, &hir::Ty<'_>)> = &mut vec![(ty, hir_ty)]; |
| |
| while let Some((ty, hir_ty)) = search_stack.pop() { |
| match (ty.kind(), &hir_ty.kind) { |
| // Check if the `ty` is `&'X ..` where `'X` |
| // is the region we are looking for -- if so, and we have a `&T` |
| // on the RHS, then we want to highlight the `&` like so: |
| // |
| // & |
| // - let's call the lifetime of this reference `'1` |
| (ty::Ref(region, referent_ty, _), hir::TyKind::Ref(_lifetime, referent_hir_ty)) => { |
| if region.as_var() == needle_fr { |
| // Just grab the first character, the `&`. |
| let source_map = self.infcx.tcx.sess.source_map(); |
| let ampersand_span = source_map.start_point(hir_ty.span); |
| |
| return Some(RegionNameHighlight::MatchedHirTy(ampersand_span)); |
| } |
| |
| // Otherwise, let's descend into the referent types. |
| search_stack.push((*referent_ty, &referent_hir_ty.ty)); |
| } |
| |
| // Match up something like `Foo<'1>` |
| ( |
| ty::Adt(_adt_def, substs), |
| hir::TyKind::Path(hir::QPath::Resolved(None, path)), |
| ) => { |
| match path.res { |
| // Type parameters of the type alias have no reason to |
| // be the same as those of the ADT. |
| // FIXME: We should be able to do something similar to |
| // match_adt_and_segment in this case. |
| Res::Def(DefKind::TyAlias, _) => (), |
| _ => { |
| if let Some(last_segment) = path.segments.last() { |
| if let Some(highlight) = self.match_adt_and_segment( |
| substs, |
| needle_fr, |
| last_segment, |
| search_stack, |
| ) { |
| return Some(highlight); |
| } |
| } |
| } |
| } |
| } |
| |
| // The following cases don't have lifetimes, so we |
| // just worry about trying to match up the rustc type |
| // with the HIR types: |
| (&ty::Tuple(elem_tys), hir::TyKind::Tup(elem_hir_tys)) => { |
| search_stack.extend(iter::zip(elem_tys, *elem_hir_tys)); |
| } |
| |
| (ty::Slice(elem_ty), hir::TyKind::Slice(elem_hir_ty)) |
| | (ty::Array(elem_ty, _), hir::TyKind::Array(elem_hir_ty, _)) => { |
| search_stack.push((*elem_ty, elem_hir_ty)); |
| } |
| |
| (ty::RawPtr(mut_ty), hir::TyKind::Ptr(mut_hir_ty)) => { |
| search_stack.push((mut_ty.ty, &mut_hir_ty.ty)); |
| } |
| |
| _ => { |
| // FIXME there are other cases that we could trace |
| } |
| } |
| } |
| |
| None |
| } |
| |
| /// We've found an enum/struct/union type with the substitutions |
| /// `substs` and -- in the HIR -- a path type with the final |
| /// segment `last_segment`. Try to find a `'_` to highlight in |
| /// the generic args (or, if not, to produce new zipped pairs of |
| /// types+hir to search through). |
| fn match_adt_and_segment<'hir>( |
| &self, |
| substs: SubstsRef<'tcx>, |
| needle_fr: RegionVid, |
| last_segment: &'hir hir::PathSegment<'hir>, |
| search_stack: &mut Vec<(Ty<'tcx>, &'hir hir::Ty<'hir>)>, |
| ) -> Option<RegionNameHighlight> { |
| // Did the user give explicit arguments? (e.g., `Foo<..>`) |
| let args = last_segment.args.as_ref()?; |
| let lifetime = |
| self.try_match_adt_and_generic_args(substs, needle_fr, args, search_stack)?; |
| if lifetime.is_anonymous() { |
| None |
| } else { |
| Some(RegionNameHighlight::MatchedAdtAndSegment(lifetime.ident.span)) |
| } |
| } |
| |
| /// We've found an enum/struct/union type with the substitutions |
| /// `substs` and -- in the HIR -- a path with the generic |
| /// arguments `args`. If `needle_fr` appears in the args, return |
| /// the `hir::Lifetime` that corresponds to it. If not, push onto |
| /// `search_stack` the types+hir to search through. |
| fn try_match_adt_and_generic_args<'hir>( |
| &self, |
| substs: SubstsRef<'tcx>, |
| needle_fr: RegionVid, |
| args: &'hir hir::GenericArgs<'hir>, |
| search_stack: &mut Vec<(Ty<'tcx>, &'hir hir::Ty<'hir>)>, |
| ) -> Option<&'hir hir::Lifetime> { |
| for (kind, hir_arg) in iter::zip(substs, args.args) { |
| match (kind.unpack(), hir_arg) { |
| (GenericArgKind::Lifetime(r), hir::GenericArg::Lifetime(lt)) => { |
| if r.as_var() == needle_fr { |
| return Some(lt); |
| } |
| } |
| |
| (GenericArgKind::Type(ty), hir::GenericArg::Type(hir_ty)) => { |
| search_stack.push((ty, hir_ty)); |
| } |
| |
| (GenericArgKind::Const(_ct), hir::GenericArg::Const(_hir_ct)) => { |
| // Lifetimes cannot be found in consts, so we don't need |
| // to search anything here. |
| } |
| |
| ( |
| GenericArgKind::Lifetime(_) |
| | GenericArgKind::Type(_) |
| | GenericArgKind::Const(_), |
| _, |
| ) => { |
| // HIR lowering sometimes doesn't catch this in erroneous |
| // programs, so we need to use delay_span_bug here. See #82126. |
| self.infcx.tcx.sess.delay_span_bug( |
| hir_arg.span(), |
| format!("unmatched subst and hir arg: found {kind:?} vs {hir_arg:?}"), |
| ); |
| } |
| } |
| } |
| |
| None |
| } |
| |
| /// Finds a closure upvar that contains `fr` and label it with a |
| /// fully elaborated type, returning something like `'1`. Result |
| /// looks like: |
| /// |
| /// ```text |
| /// | let x = Some(&22); |
| /// - fully elaborated type of `x` is `Option<&'1 u32>` |
| /// ``` |
| #[instrument(level = "trace", skip(self))] |
| fn give_name_if_anonymous_region_appears_in_upvars(&self, fr: RegionVid) -> Option<RegionName> { |
| let upvar_index = self.regioncx.get_upvar_index_for_region(self.infcx.tcx, fr)?; |
| let (upvar_name, upvar_span) = self.regioncx.get_upvar_name_and_span_for_region( |
| self.infcx.tcx, |
| &self.upvars, |
| upvar_index, |
| ); |
| let region_name = self.synthesize_region_name(); |
| |
| Some(RegionName { |
| name: region_name, |
| source: RegionNameSource::AnonRegionFromUpvar(upvar_span, upvar_name), |
| }) |
| } |
| |
| /// Checks for arguments appearing in the (closure) return type. It |
| /// must be a closure since, in a free fn, such an argument would |
| /// have to either also appear in an argument (if using elision) |
| /// or be early bound (named, not in argument). |
| #[instrument(level = "trace", skip(self))] |
| fn give_name_if_anonymous_region_appears_in_output(&self, fr: RegionVid) -> Option<RegionName> { |
| let tcx = self.infcx.tcx; |
| let hir = tcx.hir(); |
| |
| let return_ty = self.regioncx.universal_regions().unnormalized_output_ty; |
| debug!("give_name_if_anonymous_region_appears_in_output: return_ty = {:?}", return_ty); |
| if !tcx.any_free_region_meets(&return_ty, |r| r.as_var() == fr) { |
| return None; |
| } |
| |
| let mir_hir_id = self.mir_hir_id(); |
| |
| let (return_span, mir_description, hir_ty) = match hir.get(mir_hir_id) { |
| hir::Node::Expr(hir::Expr { |
| kind: hir::ExprKind::Closure(&hir::Closure { fn_decl, body, fn_decl_span, .. }), |
| .. |
| }) => { |
| let (mut span, mut hir_ty) = match fn_decl.output { |
| hir::FnRetTy::DefaultReturn(_) => { |
| (tcx.sess.source_map().end_point(fn_decl_span), None) |
| } |
| hir::FnRetTy::Return(hir_ty) => (fn_decl.output.span(), Some(hir_ty)), |
| }; |
| let mir_description = match hir.body(body).generator_kind { |
| Some(hir::GeneratorKind::Async(gen)) => match gen { |
| hir::AsyncGeneratorKind::Block => " of async block", |
| hir::AsyncGeneratorKind::Closure => " of async closure", |
| hir::AsyncGeneratorKind::Fn => { |
| let parent_item = |
| hir.get_by_def_id(hir.get_parent_item(mir_hir_id).def_id); |
| let output = &parent_item |
| .fn_decl() |
| .expect("generator lowered from async fn should be in fn") |
| .output; |
| span = output.span(); |
| if let hir::FnRetTy::Return(ret) = output { |
| hir_ty = Some(self.get_future_inner_return_ty(*ret)); |
| } |
| " of async function" |
| } |
| }, |
| Some(hir::GeneratorKind::Gen) => " of generator", |
| None => " of closure", |
| }; |
| (span, mir_description, hir_ty) |
| } |
| node => match node.fn_decl() { |
| Some(fn_decl) => { |
| let hir_ty = match fn_decl.output { |
| hir::FnRetTy::DefaultReturn(_) => None, |
| hir::FnRetTy::Return(ty) => Some(ty), |
| }; |
| (fn_decl.output.span(), "", hir_ty) |
| } |
| None => (self.body.span, "", None), |
| }, |
| }; |
| |
| let highlight = hir_ty |
| .and_then(|hir_ty| self.highlight_if_we_can_match_hir_ty(fr, return_ty, hir_ty)) |
| .unwrap_or_else(|| { |
| // `highlight_if_we_cannot_match_hir_ty` needs to know the number we will give to |
| // the anonymous region. If it succeeds, the `synthesize_region_name` call below |
| // will increment the counter, "reserving" the number we just used. |
| let counter = *self.next_region_name.try_borrow().unwrap(); |
| self.highlight_if_we_cannot_match_hir_ty(fr, return_ty, return_span, counter) |
| }); |
| |
| Some(RegionName { |
| name: self.synthesize_region_name(), |
| source: RegionNameSource::AnonRegionFromOutput(highlight, mir_description), |
| }) |
| } |
| |
| /// From the [`hir::Ty`] of an async function's lowered return type, |
| /// retrieve the `hir::Ty` representing the type the user originally wrote. |
| /// |
| /// e.g. given the function: |
| /// |
| /// ``` |
| /// async fn foo() -> i32 { 2 } |
| /// ``` |
| /// |
| /// this function, given the lowered return type of `foo`, an [`OpaqueDef`] that implements `Future<Output=i32>`, |
| /// returns the `i32`. |
| /// |
| /// [`OpaqueDef`]: hir::TyKind::OpaqueDef |
| fn get_future_inner_return_ty(&self, hir_ty: &'tcx hir::Ty<'tcx>) -> &'tcx hir::Ty<'tcx> { |
| let hir = self.infcx.tcx.hir(); |
| |
| let hir::TyKind::OpaqueDef(id, _, _) = hir_ty.kind else { |
| span_bug!( |
| hir_ty.span, |
| "lowered return type of async fn is not OpaqueDef: {:?}", |
| hir_ty |
| ); |
| }; |
| let opaque_ty = hir.item(id); |
| if let hir::ItemKind::OpaqueTy(hir::OpaqueTy { |
| bounds: |
| [ |
| hir::GenericBound::LangItemTrait( |
| hir::LangItem::Future, |
| _, |
| _, |
| hir::GenericArgs { |
| bindings: |
| [ |
| hir::TypeBinding { |
| ident: Ident { name: sym::Output, .. }, |
| kind: |
| hir::TypeBindingKind::Equality { term: hir::Term::Ty(ty) }, |
| .. |
| }, |
| ], |
| .. |
| }, |
| ), |
| ], |
| .. |
| }) = opaque_ty.kind |
| { |
| ty |
| } else { |
| span_bug!( |
| hir_ty.span, |
| "bounds from lowered return type of async fn did not match expected format: {opaque_ty:?}", |
| ); |
| } |
| } |
| |
| #[instrument(level = "trace", skip(self))] |
| fn give_name_if_anonymous_region_appears_in_yield_ty( |
| &self, |
| fr: RegionVid, |
| ) -> Option<RegionName> { |
| // Note: generators from `async fn` yield `()`, so we don't have to |
| // worry about them here. |
| let yield_ty = self.regioncx.universal_regions().yield_ty?; |
| debug!("give_name_if_anonymous_region_appears_in_yield_ty: yield_ty = {:?}", yield_ty); |
| |
| let tcx = self.infcx.tcx; |
| |
| if !tcx.any_free_region_meets(&yield_ty, |r| r.as_var() == fr) { |
| return None; |
| } |
| |
| let mut highlight = RegionHighlightMode::new(tcx); |
| highlight.highlighting_region_vid(fr, *self.next_region_name.try_borrow().unwrap()); |
| let type_name = |
| self.infcx.extract_inference_diagnostics_data(yield_ty.into(), Some(highlight)).name; |
| |
| let yield_span = match tcx.hir().get(self.mir_hir_id()) { |
| hir::Node::Expr(hir::Expr { |
| kind: hir::ExprKind::Closure(&hir::Closure { fn_decl_span, .. }), |
| .. |
| }) => tcx.sess.source_map().end_point(fn_decl_span), |
| _ => self.body.span, |
| }; |
| |
| debug!( |
| "give_name_if_anonymous_region_appears_in_yield_ty: \ |
| type_name = {:?}, yield_span = {:?}", |
| yield_span, type_name, |
| ); |
| |
| Some(RegionName { |
| name: self.synthesize_region_name(), |
| source: RegionNameSource::AnonRegionFromYieldTy(yield_span, type_name), |
| }) |
| } |
| |
| fn give_name_if_anonymous_region_appears_in_impl_signature( |
| &self, |
| fr: RegionVid, |
| ) -> Option<RegionName> { |
| let ty::ReEarlyBound(region) = *self.to_error_region(fr)? else { |
| return None; |
| }; |
| if region.has_name() { |
| return None; |
| }; |
| |
| let tcx = self.infcx.tcx; |
| let region_parent = tcx.parent(region.def_id); |
| let DefKind::Impl { .. } = tcx.def_kind(region_parent) else { |
| return None; |
| }; |
| |
| let found = tcx.any_free_region_meets(&tcx.type_of(region_parent).subst_identity(), |r| { |
| *r == ty::ReEarlyBound(region) |
| }); |
| |
| Some(RegionName { |
| name: self.synthesize_region_name(), |
| source: RegionNameSource::AnonRegionFromImplSignature( |
| tcx.def_span(region.def_id), |
| // FIXME(compiler-errors): Does this ever actually show up |
| // anywhere other than the self type? I couldn't create an |
| // example of a `'_` in the impl's trait being referenceable. |
| if found { "self type" } else { "header" }, |
| ), |
| }) |
| } |
| |
| fn give_name_if_anonymous_region_appears_in_arg_position_impl_trait( |
| &self, |
| fr: RegionVid, |
| ) -> Option<RegionName> { |
| let ty::ReEarlyBound(region) = *self.to_error_region(fr)? else { |
| return None; |
| }; |
| if region.has_name() { |
| return None; |
| }; |
| |
| let predicates = self |
| .infcx |
| .tcx |
| .predicates_of(self.body.source.def_id()) |
| .instantiate_identity(self.infcx.tcx) |
| .predicates; |
| |
| if let Some(upvar_index) = self |
| .regioncx |
| .universal_regions() |
| .defining_ty |
| .upvar_tys() |
| .position(|ty| self.any_param_predicate_mentions(&predicates, ty, region)) |
| { |
| let (upvar_name, upvar_span) = self.regioncx.get_upvar_name_and_span_for_region( |
| self.infcx.tcx, |
| &self.upvars, |
| upvar_index, |
| ); |
| let region_name = self.synthesize_region_name(); |
| |
| Some(RegionName { |
| name: region_name, |
| source: RegionNameSource::AnonRegionFromUpvar(upvar_span, upvar_name), |
| }) |
| } else if let Some(arg_index) = self |
| .regioncx |
| .universal_regions() |
| .unnormalized_input_tys |
| .iter() |
| .position(|ty| self.any_param_predicate_mentions(&predicates, *ty, region)) |
| { |
| let (arg_name, arg_span) = self.regioncx.get_argument_name_and_span_for_region( |
| self.body, |
| &self.local_names, |
| arg_index, |
| ); |
| let region_name = self.synthesize_region_name(); |
| |
| Some(RegionName { |
| name: region_name, |
| source: RegionNameSource::AnonRegionFromArgument( |
| RegionNameHighlight::CannotMatchHirTy(arg_span, arg_name?.to_string()), |
| ), |
| }) |
| } else { |
| None |
| } |
| } |
| |
| fn any_param_predicate_mentions( |
| &self, |
| predicates: &[ty::Predicate<'tcx>], |
| ty: Ty<'tcx>, |
| region: ty::EarlyBoundRegion, |
| ) -> bool { |
| let tcx = self.infcx.tcx; |
| ty.walk().any(|arg| { |
| if let ty::GenericArgKind::Type(ty) = arg.unpack() |
| && let ty::Param(_) = ty.kind() |
| { |
| predicates.iter().any(|pred| { |
| match pred.kind().skip_binder() { |
| ty::PredicateKind::Clause(ty::Clause::Trait(data)) if data.self_ty() == ty => {} |
| ty::PredicateKind::Clause(ty::Clause::Projection(data)) if data.projection_ty.self_ty() == ty => {} |
| _ => return false, |
| } |
| tcx.any_free_region_meets(pred, |r| { |
| *r == ty::ReEarlyBound(region) |
| }) |
| }) |
| } else { |
| false |
| } |
| }) |
| } |
| } |
