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Compute lifetimes in scope at diagnostic time.

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This commit is contained in:
Camille GILLOT 2022-05-07 22:41:53 +02:00
parent cb0584f86b
commit a07290047e
9 changed files with 101 additions and 94 deletions
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7
compiler/rustc_ast_lowering/src/index.rs
View File

@ -313,6 +313,13 @@ impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
});
}
fn visit_assoc_type_binding(&mut self, type_binding: &'hir TypeBinding<'hir>) {
self.insert(type_binding.span, type_binding.hir_id, Node::TypeBinding(type_binding));
self.with_parent(type_binding.hir_id, |this| {
intravisit::walk_assoc_type_binding(this, type_binding)
})
}
fn visit_trait_item_ref(&mut self, ii: &'hir TraitItemRef) {
// Do not visit the duplicate information in TraitItemRef. We want to
// map the actual nodes, not the duplicate ones in the *Ref.

2
compiler/rustc_hir/src/hir.rs
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@ -3302,6 +3302,7 @@ pub enum Node<'hir> {
Stmt(&'hir Stmt<'hir>),
PathSegment(&'hir PathSegment<'hir>),
Ty(&'hir Ty<'hir>),
TypeBinding(&'hir TypeBinding<'hir>),
TraitRef(&'hir TraitRef<'hir>),
Binding(&'hir Pat<'hir>),
Pat(&'hir Pat<'hir>),
@ -3347,6 +3348,7 @@ impl<'hir> Node<'hir> {
| Node::PathSegment(PathSegment { ident, .. }) => Some(*ident),
Node::Lifetime(lt) => Some(lt.name.ident()),
Node::GenericParam(p) => Some(p.name.ident()),
Node::TypeBinding(b) => Some(b.ident),
Node::Param(..)
| Node::AnonConst(..)
| Node::Expr(..)

35
compiler/rustc_hir_pretty/src/lib.rs
View File

@ -85,6 +85,7 @@ impl<'a> State<'a> {
Node::Stmt(a) => self.print_stmt(&a),
Node::PathSegment(a) => self.print_path_segment(&a),
Node::Ty(a) => self.print_type(&a),
Node::TypeBinding(a) => self.print_type_binding(&a),
Node::TraitRef(a) => self.print_trait_ref(&a),
Node::Binding(a) | Node::Pat(a) => self.print_pat(&a),
Node::Arm(a) => self.print_arm(&a),
@ -1703,21 +1704,7 @@ impl<'a> State<'a> {
for binding in generic_args.bindings.iter() {
start_or_comma(self);
self.print_ident(binding.ident);
self.print_generic_args(binding.gen_args, false, false);
self.space();
match generic_args.bindings[0].kind {
hir::TypeBindingKind::Equality { ref term } => {
self.word_space("=");
match term {
Term::Ty(ref ty) => self.print_type(ty),
Term::Const(ref c) => self.print_anon_const(c),
}
}
hir::TypeBindingKind::Constraint { bounds } => {
self.print_bounds(":", bounds);
}
}
self.print_type_binding(binding);
}
if !empty.get() {
@ -1726,6 +1713,24 @@ impl<'a> State<'a> {
}
}
pub fn print_type_binding(&mut self, binding: &hir::TypeBinding<'_>) {
self.print_ident(binding.ident);
self.print_generic_args(binding.gen_args, false, false);
self.space();
match binding.kind {
hir::TypeBindingKind::Equality { ref term } => {
self.word_space("=");
match term {
Term::Ty(ref ty) => self.print_type(ty),
Term::Const(ref c) => self.print_anon_const(c),
}
}
hir::TypeBindingKind::Constraint { bounds } => {
self.print_bounds(":", bounds);
}
}
}
pub fn print_pat(&mut self, pat: &hir::Pat<'_>) {
self.maybe_print_comment(pat.span.lo());
self.ann.pre(self, AnnNode::Pat(pat));

6
compiler/rustc_middle/src/hir/map/mod.rs
View File

@ -298,6 +298,7 @@ impl<'hir> Map<'hir> {
Node::Stmt(_)
| Node::PathSegment(_)
| Node::Ty(_)
| Node::TypeBinding(_)
| Node::Infer(_)
| Node::TraitRef(_)
| Node::Pat(_)
@ -323,7 +324,8 @@ impl<'hir> Map<'hir> {
}
pub fn get_parent_node(self, hir_id: HirId) -> HirId {
self.find_parent_node(hir_id).unwrap()
self.find_parent_node(hir_id)
.unwrap_or_else(|| bug!("No parent for node {:?}", self.node_to_string(hir_id)))
}
/// Retrieves the `Node` corresponding to `id`, returning `None` if cannot be found.
@ -973,6 +975,7 @@ impl<'hir> Map<'hir> {
.with_hi(seg.args.map_or_else(|| ident_span.hi(), |args| args.span_ext.hi()))
}
Node::Ty(ty) => ty.span,
Node::TypeBinding(tb) => tb.span,
Node::TraitRef(tr) => tr.path.span,
Node::Binding(pat) => pat.span,
Node::Pat(pat) => pat.span,
@ -1205,6 +1208,7 @@ fn hir_id_to_string(map: Map<'_>, id: HirId) -> String {
Some(Node::Stmt(_)) => node_str("stmt"),
Some(Node::PathSegment(_)) => node_str("path segment"),
Some(Node::Ty(_)) => node_str("type"),
Some(Node::TypeBinding(_)) => node_str("type binding"),
Some(Node::TraitRef(_)) => node_str("trait ref"),
Some(Node::Binding(_)) => node_str("local"),
Some(Node::Pat(_)) => node_str("pat"),

3
compiler/rustc_middle/src/middle/resolve_lifetime.rs
View File

@ -23,8 +23,7 @@ pub enum Region {
pub enum LifetimeScopeForPath {
/// Contains all lifetime names that are in scope and could possibly be used in generics
/// arguments of path.
NonElided(Vec<LocalDefId>),
NonElided,
/// Information that allows us to suggest args of the form `<'_>` in case
/// no generic arguments were provided for a path.
Elided,

33
compiler/rustc_resolve/src/late/lifetimes.rs
View File

@ -517,30 +517,16 @@ fn late_region_as_bound_region<'tcx>(tcx: TyCtxt<'tcx>, region: &Region) -> ty::
#[tracing::instrument(level = "debug")]
fn get_lifetime_scopes_for_path(mut scope: &Scope<'_>) -> LifetimeScopeForPath {
let mut available_lifetimes = vec![];
loop {
match scope {
Scope::Binder { lifetimes, s, .. } => {
available_lifetimes.extend(lifetimes.keys());
scope = s;
}
Scope::Body { s, .. } => {
scope = s;
}
Scope::Elision { elide, s } => {
if let Elide::Exact(_) = elide {
return LifetimeScopeForPath::Elided;
} else {
scope = s;
}
}
Scope::ObjectLifetimeDefault { s, .. } => {
scope = s;
}
Scope::Root => {
return LifetimeScopeForPath::NonElided(available_lifetimes);
}
Scope::Supertrait { s, .. } | Scope::TraitRefBoundary { s, .. } => {
Scope::Elision { elide: Elide::Exact(_), .. } => return LifetimeScopeForPath::Elided,
Scope::Root => return LifetimeScopeForPath::NonElided,
Scope::Binder { s, .. }
| Scope::Body { s, .. }
| Scope::ObjectLifetimeDefault { s, .. }
| Scope::Supertrait { s, .. }
| Scope::TraitRefBoundary { s, .. }
| Scope::Elision { s, .. } => {
scope = s;
}
}
@ -2170,6 +2156,9 @@ impl<'a, 'tcx> LifetimeContext<'a, 'tcx> {
// Foreign functions, `fn(...) -> R` and `Trait(...) -> R` (both types and bounds).
Node::ForeignItem(_) | Node::Ty(_) | Node::TraitRef(_) => None,
Node::TypeBinding(_) if let Node::TraitRef(_) = self.tcx.hir().get(self.tcx.hir().get_parent_node(parent)) => None,
// Everything else (only closures?) doesn't
// actually enjoy elision in return types.
_ => {

1
compiler/rustc_typeck/src/check/generator_interior/drop_ranges/cfg_build.rs
View File

@ -249,6 +249,7 @@ impl<'a, 'tcx> DropRangeVisitor<'a, 'tcx> {
| hir::Node::Stmt(..)
| hir::Node::PathSegment(..)
| hir::Node::Ty(..)
| hir::Node::TypeBinding(..)
| hir::Node::TraitRef(..)
| hir::Node::Binding(..)
| hir::Node::Pat(..)

19
compiler/rustc_typeck/src/collect/type_of.rs
View File

@ -450,21 +450,10 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: DefId) -> Ty<'_> {
.discr_type()
.to_ty(tcx),
Node::TraitRef(trait_ref @ &TraitRef {
path, ..
}) if let Some((binding, seg)) =
path
.segments
.iter()
.find_map(|seg| {
seg.args?.bindings
.iter()
.find_map(|binding| if binding.opt_const()?.hir_id == hir_id {
Some((binding, seg))
} else {
None
})
}) =>
Node::TypeBinding(binding @ &TypeBinding { hir_id: binding_id, .. })
if let Node::TraitRef(trait_ref) = tcx.hir().get(
tcx.hir().get_parent_node(binding_id)
) =>
{
let Some(trait_def_id) = trait_ref.trait_def_id() else {
return tcx.ty_error_with_message(DUMMY_SP, "Could not find trait");

89
compiler/rustc_typeck/src/structured_errors/wrong_number_of_generic_args.rs
View File

@ -291,7 +291,52 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> {
}
// Creates lifetime name suggestions from the lifetime parameter names
fn get_lifetime_args_suggestions_from_param_names(&self, num_params_to_take: usize) -> String {
fn get_lifetime_args_suggestions_from_param_names(
&self,
path_hir_id: Option<hir::HirId>,
num_params_to_take: usize,
) -> String {
debug!(?path_hir_id);
if let Some(path_hir_id) = path_hir_id {
// We first try to get lifetime name suggestions from scope or elision information.
// If none is available we use the parameter definitions
if let Some(LifetimeScopeForPath::Elided) = self.tcx.lifetime_scope(path_hir_id) {
// Use suggestions of the form `<'_, '_>` in case lifetime can be elided
return ["'_"].repeat(num_params_to_take).join(",");
}
let mut ret = Vec::new();
for (id, node) in self.tcx.hir().parent_iter(path_hir_id) {
debug!(?id);
let params = if let Some(generics) = node.generics() {
generics.params
} else if let hir::Node::Ty(ty) = node
&& let hir::TyKind::BareFn(bare_fn) = ty.kind
{
bare_fn.generic_params
} else {
&[]
};
ret.extend(params.iter().filter_map(|p| {
let hir::GenericParamKind::Lifetime { kind: hir::LifetimeParamKind::Explicit }
= p.kind
else { return None };
let hir::ParamName::Plain(name) = p.name else { return None };
Some(name.to_string())
}));
if ret.len() >= num_params_to_take {
return ret[..num_params_to_take].join(", ");
}
// We cannot refer to lifetimes defined in an outer function.
if let hir::Node::Item(_) = node {
break;
}
}
}
// We could not gather enough lifetime parameters in the scope.
// We use the parameter names from the target type's definition instead.
self.gen_params
.params
.iter()
@ -501,44 +546,10 @@ impl<'a, 'tcx> WrongNumberOfGenericArgs<'a, 'tcx> {
let num_params_to_take = num_missing_args;
let msg = format!("add missing {} argument{}", self.kind(), pluralize!(num_missing_args));
// we first try to get lifetime name suggestions from scope or elision information. If none is
// available we use the parameter definitions
let suggested_args = if let Some(hir_id) = self.path_segment.hir_id {
if let Some(lifetimes_in_scope) = self.tcx.lifetime_scope(hir_id) {
match lifetimes_in_scope {
LifetimeScopeForPath::NonElided(param_names) => {
debug!("NonElided(param_names: {:?})", param_names);
if param_names.len() >= num_params_to_take {
// use lifetime parameters in scope for suggestions
param_names
.iter()
.take(num_params_to_take)
.map(|def_id| {
self.tcx.item_name(def_id.to_def_id()).to_ident_string()
})
.collect::<Vec<_>>()
.join(", ")
} else {
// Not enough lifetime arguments in scope -> create suggestions from
// lifetime parameter names in definition. An error for the incorrect
// lifetime scope will be output later.
self.get_lifetime_args_suggestions_from_param_names(num_params_to_take)
}
}
LifetimeScopeForPath::Elided => {
debug!("Elided");
// use suggestions of the form `<'_, '_>` in case lifetime can be elided
["'_"].repeat(num_params_to_take).join(",")
}
}
} else {
self.get_lifetime_args_suggestions_from_param_names(num_params_to_take)
}
} else {
self.get_lifetime_args_suggestions_from_param_names(num_params_to_take)
};
let suggested_args = self.get_lifetime_args_suggestions_from_param_names(
self.path_segment.hir_id,
num_params_to_take,
);
debug!("suggested_args: {:?}", &suggested_args);
match self.angle_brackets {