+++ /dev/null
-use std::fmt::{self, Display};
-use std::iter;
-
-use rustc_errors::DiagnosticBuilder;
-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::borrow_check::{nll::ToRegionVid, 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)]
-crate struct RegionName {
- /// The name of the region (interned).
- crate name: Symbol,
- /// Where the region comes from.
- 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)]
-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, String),
- /// The region corresponding to an argument.
- AnonRegionFromArgument(RegionNameHighlight),
- /// The region corresponding to a closure upvar.
- AnonRegionFromUpvar(Span, String),
- /// The region corresponding to the return type of a closure.
- AnonRegionFromOutput(RegionNameHighlight, String),
- /// The region from a type yielded by a generator.
- AnonRegionFromYieldTy(Span, String),
- /// An anonymous region from an async fn.
- AnonRegionFromAsyncFn(Span),
-}
-
-/// 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)]
-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 {
- 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(..) => false,
- }
- }
-
- 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) => 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),
- },
- }
- }
-
- crate fn highlight_region_name(&self, diag: &mut DiagnosticBuilder<'_>) {
- match &self.source {
- RegionNameSource::NamedFreeRegion(span)
- | RegionNameSource::NamedEarlyBoundRegion(span) => {
- diag.span_label(*span, format!("lifetime `{}` defined here", self));
- }
- RegionNameSource::SynthesizedFreeEnvRegion(span, note) => {
- diag.span_label(
- *span,
- format!("lifetime `{}` represents this closure's body", self),
- );
- diag.note(¬e);
- }
- 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 `{}` appears in the type {}", self, type_name),
- );
- }
- RegionNameSource::AnonRegionFromOutput(
- RegionNameHighlight::Occluded(span, type_name),
- mir_description,
- ) => {
- diag.span_label(
- *span,
- format!(
- "return type{} `{}` contains a lifetime `{}`",
- mir_description, type_name, self
- ),
- );
- }
- RegionNameSource::AnonRegionFromUpvar(span, upvar_name) => {
- diag.span_label(
- *span,
- format!("lifetime `{}` appears in the type of `{}`", self, upvar_name),
- );
- }
- RegionNameSource::AnonRegionFromOutput(
- RegionNameHighlight::CannotMatchHirTy(span, type_name),
- mir_description,
- ) => {
- diag.span_label(*span, format!("return type{} is {}", mir_description, type_name));
- }
- RegionNameSource::AnonRegionFromYieldTy(span, type_name) => {
- diag.span_label(*span, format!("yield type is {}", type_name));
- }
- RegionNameSource::Static => {}
- }
- }
-}
-
-impl Display for RegionName {
- fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
- write!(f, "{}", self.name)
- }
-}
-
-impl<'tcx> MirBorrowckCtxt<'_, 'tcx> {
- crate fn mir_def_id(&self) -> hir::def_id::LocalDefId {
- self.body.source.def_id().as_local().unwrap()
- }
-
- 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.
- 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`:
- ///
- /// ```
- /// 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.
- 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));
-
- if let Some(ref 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.
- 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) => {
- if ebr.has_name() {
- let span = tcx.hir().span_if_local(ebr.def_id).unwrap_or(DUMMY_SP);
- Some(RegionName {
- name: ebr.name,
- source: RegionNameSource::NamedEarlyBoundRegion(span),
- })
- } else {
- None
- }
- }
-
- 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 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),
- })
- }
- }
-
- ty::BoundRegionKind::BrEnv => {
- let def_ty = self.regioncx.universal_regions().defining_ty;
-
- if let DefiningTy::Closure(_, substs) = def_ty {
- let args_span = if let hir::ExprKind::Closure(_, _, _, span, _) =
- tcx.hir().expect_expr(self.mir_hir_id()).kind
- {
- span
- } 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(
- args_span,
- note.to_string(),
- ),
- })
- } else {
- // Can't have BrEnv in functions, constants or generators.
- bug!("BrEnv outside of closure.");
- }
- }
-
- ty::BoundRegionKind::BrAnon(_) => None,
- },
-
- ty::ReLateBound(..)
- | ty::ReVar(..)
- | ty::RePlaceholder(..)
- | ty::ReEmpty(_)
- | ty::ReErased => 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`
- /// ```
- 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::default();
- 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::Rptr(_lifetime, referent_hir_ty),
- ) => {
- if region.to_region_vid() == 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.iter().map(|k| k.expect_ty()), *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)?;
- match lifetime.name {
- hir::LifetimeName::Param(_)
- | hir::LifetimeName::Error
- | hir::LifetimeName::Static
- | hir::LifetimeName::Underscore => {
- let lifetime_span = lifetime.span;
- Some(RegionNameHighlight::MatchedAdtAndSegment(lifetime_span))
- }
-
- hir::LifetimeName::ImplicitObjectLifetimeDefault | hir::LifetimeName::Implicit => {
- // In this case, the user left off the lifetime; so
- // they wrote something like:
- //
- // ```
- // x: Foo<T>
- // ```
- //
- // where the fully elaborated form is `Foo<'_, '1,
- // T>`. We don't consider this a match; instead we let
- // the "fully elaborated" type fallback above handle
- // it.
- None
- }
- }
- }
-
- /// 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.to_region_vid() == 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 {:?} vs {:?}", kind, 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>`
- /// ```
- 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.to_string()),
- })
- }
-
- /// 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).
- 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.to_region_vid() == 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(_, return_ty, body_id, span, _),
- ..
- }) => {
- let (mut span, mut hir_ty) = match return_ty.output {
- hir::FnRetTy::DefaultReturn(_) => {
- (tcx.sess.source_map().end_point(*span), None)
- }
- hir::FnRetTy::Return(hir_ty) => (return_ty.output.span(), Some(hir_ty)),
- };
- let mir_description = match hir.body(*body_id).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(hir.get_parent_item(mir_hir_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.to_string()),
- })
- }
-
- /// 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 {}
- /// ```
- ///
- /// 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();
-
- if let hir::TyKind::OpaqueDef(id, _) = hir_ty.kind {
- 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 { 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
- );
- }
- } else {
- span_bug!(
- hir_ty.span,
- "lowered return type of async fn is not OpaqueDef: {:?}",
- hir_ty
- );
- }
- }
-
- 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.to_region_vid() == fr) {
- return None;
- }
-
- let mut highlight = RegionHighlightMode::default();
- 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(_, _, _, span, _), ..
- }) => (tcx.sess.source_map().end_point(*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),
- })
- }
-}
projects / rustc.git / blobdiff