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Make late_bound_lifetime_arguments a hard error. #108782

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Make late_bound_lifetime_arguments a hard error. #108782

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7ad5f31
Make late_bound_lifetime_arguments a hard error.
cjgillot Oct 22, 2022
bf7e7a5
Always pass a &PathSegment in astconv.
cjgillot Mar 5, 2023
270fa94
Make a proper suggestion.
cjgillot Mar 5, 2023
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95 changes: 54 additions & 41 deletions compiler/rustc_hir_analysis/src/astconv/generics.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,15 +6,14 @@ use crate::astconv::{
use crate::errors::AssocTypeBindingNotAllowed;
use crate::structured_errors::{GenericArgsInfo, StructuredDiagnostic, WrongNumberOfGenericArgs};
use rustc_ast::ast::ParamKindOrd;
use rustc_errors::{struct_span_err, Applicability, Diagnostic, ErrorGuaranteed, MultiSpan};
use rustc_errors::{struct_span_err, Applicability, Diagnostic, ErrorGuaranteed};
use rustc_hir as hir;
use rustc_hir::def::{DefKind, Res};
use rustc_hir::def_id::DefId;
use rustc_hir::GenericArg;
use rustc_middle::ty::{
self, subst, subst::SubstsRef, GenericParamDef, GenericParamDefKind, IsSuggestable, Ty, TyCtxt,
};
use rustc_session::lint::builtin::LATE_BOUND_LIFETIME_ARGUMENTS;
use rustc_span::{symbol::kw, Span};
use smallvec::SmallVec;

Expand Down Expand Up @@ -383,25 +382,13 @@ pub fn check_generic_arg_count_for_call(
seg: &hir::PathSegment<'_>,
is_method_call: IsMethodCall,
) -> GenericArgCountResult {
let empty_args = hir::GenericArgs::none();
let gen_args = seg.args.unwrap_or(&empty_args);
let gen_pos = match is_method_call {
IsMethodCall::Yes => GenericArgPosition::MethodCall,
IsMethodCall::No => GenericArgPosition::Value,
};
let has_self = generics.parent.is_none() && generics.has_self;

check_generic_arg_count(
tcx,
span,
def_id,
seg,
generics,
gen_args,
gen_pos,
has_self,
seg.infer_args,
)
check_generic_arg_count(tcx, span, def_id, seg, generics, gen_pos, has_self)
}

/// Checks that the correct number of generic arguments have been provided.
Expand All @@ -413,13 +400,12 @@ pub(crate) fn check_generic_arg_count(
def_id: DefId,
seg: &hir::PathSegment<'_>,
gen_params: &ty::Generics,
gen_args: &hir::GenericArgs<'_>,
gen_pos: GenericArgPosition,
has_self: bool,
infer_args: bool,
) -> GenericArgCountResult {
let default_counts = gen_params.own_defaults();
let param_counts = gen_params.own_counts();
let gen_args = seg.args();

// Subtracting from param count to ensure type params synthesized from `impl Trait`
// cannot be explicitly specified.
Expand All @@ -430,14 +416,13 @@ pub(crate) fn check_generic_arg_count(
.count();
let named_type_param_count = param_counts.types - has_self as usize - synth_type_param_count;
let infer_lifetimes =
(gen_pos != GenericArgPosition::Type || infer_args) && !gen_args.has_lifetime_params();
(gen_pos != GenericArgPosition::Type || seg.infer_args) && !gen_args.has_lifetime_params();

if gen_pos != GenericArgPosition::Type && let Some(b) = gen_args.bindings.first() {
prohibit_assoc_ty_binding(tcx, b.span);
}

let explicit_late_bound =
prohibit_explicit_late_bound_lifetimes(tcx, gen_params, gen_args, gen_pos);
let explicit_late_bound = prohibit_explicit_late_bound_lifetimes(tcx, gen_params, seg, gen_pos);

let mut invalid_args = vec![];

Expand Down Expand Up @@ -561,7 +546,7 @@ pub(crate) fn check_generic_arg_count(
};

let args_correct = {
let expected_min = if infer_args {
let expected_min = if seg.infer_args {
0
} else {
param_counts.consts + named_type_param_count
Expand Down Expand Up @@ -599,10 +584,10 @@ pub fn prohibit_assoc_ty_binding(tcx: TyCtxt<'_>, span: Span) {
pub(crate) fn prohibit_explicit_late_bound_lifetimes(
tcx: TyCtxt<'_>,
def: &ty::Generics,
args: &hir::GenericArgs<'_>,
seg: &hir::PathSegment<'_>,
position: GenericArgPosition,
) -> ExplicitLateBound {
let param_counts = def.own_counts();
let args = seg.args();
let infer_lifetimes = position != GenericArgPosition::Type && !args.has_lifetime_params();

if infer_lifetimes {
Expand All @@ -611,27 +596,55 @@ pub(crate) fn prohibit_explicit_late_bound_lifetimes(

if let Some(span_late) = def.has_late_bound_regions {
let msg = "cannot specify lifetime arguments explicitly \
if late bound lifetime parameters are present";
if late bound lifetime parameters are present";
let note = "the late bound lifetime parameter is introduced here";
let span = args.args[0].span();

if position == GenericArgPosition::Value
&& args.num_lifetime_params() != param_counts.lifetimes
{
let mut err = tcx.sess.struct_span_err(span, msg);
err.span_note(span_late, note);
err.emit();
let help = format!(
"remove the explicit lifetime argument{}",
rustc_errors::pluralize!(args.num_lifetime_params())
);
let spans: Vec<_> = args
.args
.iter()
.filter_map(|arg| match arg {
hir::GenericArg::Lifetime(l) => Some(l.ident.span),
_ => None,
})
.collect();

let mut err = tcx.sess.struct_span_err(spans, msg);
err.span_note(span_late, note);

let mut suggestions = vec![];
if let Some(span_ext) = args.span_ext() {
if args.num_lifetime_params() == args.args.len()
&& span_ext.ctxt() == seg.ident.span.ctxt()
{
// We only specify lifetime args, so suggest to remove everything.
suggestions.push((seg.ident.span.shrink_to_hi().to(span_ext), String::new()));
} else {
for [arg, next_arg] in args.args.array_windows() {
if let hir::GenericArg::Lifetime(lifetime) = arg
&& let Some(arg_span) = lifetime.ident.span.find_ancestor_inside(span_ext)
&& let Some(next_span_lo) = next_arg.span().shrink_to_lo().find_ancestor_inside(span_ext)
{
suggestions.push((arg_span.with_hi(next_span_lo.lo()), String::new()));
}
}

if let Some(arg) = args.args.last()
&& let hir::GenericArg::Lifetime(lifetime) = arg
&& let Some(arg_span) = lifetime.ident.span.find_ancestor_inside(span_ext)
{
suggestions.push((arg_span, String::new()));
}
}
}
if !suggestions.is_empty() {
err.multipart_suggestion_verbose(help, suggestions, Applicability::MachineApplicable);
} else {
let mut multispan = MultiSpan::from_span(span);
multispan.push_span_label(span_late, note);
tcx.struct_span_lint_hir(
LATE_BOUND_LIFETIME_ARGUMENTS,
args.args[0].hir_id(),
multispan,
msg,
|lint| lint,
);
err.help(help);
}
err.emit();

ExplicitLateBound::Yes
} else {
Expand Down
39 changes: 11 additions & 28 deletions compiler/rustc_hir_analysis/src/astconv/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -288,8 +288,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
def_id,
&[],
item_segment,
item_segment.args(),
item_segment.infer_args,
None,
ty::BoundConstness::NotConst,
);
Expand Down Expand Up @@ -332,14 +330,12 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
/// type itself: `['a]`. The returned `SubstsRef` concatenates these two
/// lists: `[Vec<u8>, u8, 'a]`.
#[instrument(level = "debug", skip(self, span), ret)]
fn create_substs_for_ast_path<'a>(
fn create_substs_for_ast_path(
&self,
span: Span,
def_id: DefId,
parent_substs: &[subst::GenericArg<'tcx>],
seg: &hir::PathSegment<'_>,
generic_args: &'a hir::GenericArgs<'_>,
infer_args: bool,
self_ty: Option<Ty<'tcx>>,
constness: ty::BoundConstness,
) -> (SubstsRef<'tcx>, GenericArgCountResult) {
Expand Down Expand Up @@ -370,10 +366,8 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
def_id,
seg,
generics,
generic_args,
GenericArgPosition::Type,
self_ty.is_some(),
infer_args,
);

// Skip processing if type has no generic parameters.
Expand Down Expand Up @@ -540,9 +534,9 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
astconv: self,
def_id,
span,
generic_args,
generic_args: seg.args(),
inferred_params: vec![],
infer_args,
infer_args: seg.infer_args,
};
let substs = create_substs_for_generic_args(
tcx,
Expand Down Expand Up @@ -623,8 +617,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
item_def_id,
parent_substs,
item_segment,
item_segment.args(),
item_segment.infer_args,
None,
ty::BoundConstness::NotConst,
);
Expand Down Expand Up @@ -671,17 +663,13 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
trait_ref_span: Span,
trait_def_id: DefId,
trait_segment: &hir::PathSegment<'_>,
args: &GenericArgs<'_>,
infer_args: bool,
self_ty: Ty<'tcx>,
) -> GenericArgCountResult {
let (substs, arg_count) = self.create_substs_for_ast_path(
trait_ref_span,
trait_def_id,
&[],
trait_segment,
args,
infer_args,
Some(self_ty),
constness,
);
Expand All @@ -690,7 +678,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
let bound_vars = tcx.late_bound_vars(hir_id);
debug!(?bound_vars);

let assoc_bindings = self.create_assoc_bindings_for_generic_args(args);
let assoc_bindings = self.create_assoc_bindings_for_generic_args(trait_segment.args());

let poly_trait_ref =
ty::Binder::bind_with_vars(tcx.mk_trait_ref(trait_def_id, substs), bound_vars);
Expand Down Expand Up @@ -751,8 +739,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
let trait_ref_span = trait_ref.path.span;
let trait_def_id = trait_ref.trait_def_id().unwrap_or_else(|| FatalError.raise());
let trait_segment = trait_ref.path.segments.last().unwrap();
let args = trait_segment.args();
let infer_args = trait_segment.infer_args;

self.prohibit_generics(trait_ref.path.segments.split_last().unwrap().1.iter(), |_| {});
self.complain_about_internal_fn_trait(span, trait_def_id, trait_segment, false);
Expand All @@ -767,8 +753,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
trait_ref_span,
trait_def_id,
trait_segment,
args,
infer_args,
self_ty,
)
}
Expand All @@ -787,8 +771,13 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
let speculative = false;
let trait_ref_span = span;
let trait_def_id = self.tcx().require_lang_item(lang_item, Some(span));
let trait_segment = &hir::PathSegment::invalid();
let infer_args = false;
let trait_segment = &hir::PathSegment {
ident: Ident::empty(),
hir_id: hir::HirId::INVALID,
res: Res::Err,
args: Some(args),
infer_args: false,
};

self.instantiate_poly_trait_ref_inner(
hir_id,
Expand All @@ -800,8 +789,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
trait_ref_span,
trait_def_id,
trait_segment,
args,
infer_args,
self_ty,
);
}
Expand Down Expand Up @@ -846,8 +833,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
trait_def_id,
&[],
trait_segment,
trait_segment.args(),
trait_segment.infer_args,
Some(self_ty),
constness,
)
Expand Down Expand Up @@ -3074,8 +3059,6 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
def_id,
&[],
&hir::PathSegment::invalid(),
&GenericArgs::none(),
true,
None,
ty::BoundConstness::NotConst,
);
Expand Down
1 change: 1 addition & 0 deletions compiler/rustc_hir_analysis/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,7 @@ This API is completely unstable and subject to change.

#![allow(rustc::potential_query_instability)]
#![doc(html_root_url = "https://doc.rust-lang.org/nightly/nightly-rustc/")]
#![feature(array_windows)]
#![feature(box_patterns)]
#![feature(control_flow_enum)]
#![feature(drain_filter)]
Expand Down
5 changes: 5 additions & 0 deletions compiler/rustc_lint/src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -504,6 +504,11 @@ fn register_builtins(store: &mut LintStore) {
"converted into hard error, see issue #82523 \
<https://github.com/rust-lang/rust/issues/82523> for more information",
);
store.register_removed(
"late_bound_lifetime_arguments",
"converted into hard error, see issue #42868 \
<https://github.com/rust-lang/rust/issues/42868> for more information",
);
}

fn register_internals(store: &mut LintStore) {
Expand Down
42 changes: 0 additions & 42 deletions compiler/rustc_lint_defs/src/builtin.rs
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Expand Up @@ -1350,47 +1350,6 @@ declare_lint! {
};
}

declare_lint! {
/// The `late_bound_lifetime_arguments` lint detects generic lifetime
/// arguments in path segments with late bound lifetime parameters.
///
/// ### Example
///
/// ```rust
/// struct S;
///
/// impl S {
/// fn late(self, _: &u8, _: &u8) {}
/// }
///
/// fn main() {
/// S.late::<'static>(&0, &0);
/// }
/// ```
///
/// {{produces}}
///
/// ### Explanation
///
/// It is not clear how to provide arguments for early-bound lifetime
/// parameters if they are intermixed with late-bound parameters in the
/// same list. For now, providing any explicit arguments will trigger this
/// lint if late-bound parameters are present, so in the future a solution
/// can be adopted without hitting backward compatibility issues. This is
/// a [future-incompatible] lint to transition this to a hard error in the
/// future. See [issue #42868] for more details, along with a description
/// of the difference between early and late-bound parameters.
///
/// [issue #42868]: https://github.com/rust-lang/rust/issues/42868
/// [future-incompatible]: ../index.md#future-incompatible-lints
pub LATE_BOUND_LIFETIME_ARGUMENTS,
Warn,
"detects generic lifetime arguments in path segments with late bound lifetime parameters",
@future_incompatible = FutureIncompatibleInfo {
reference: "issue #42868 <https://github.com/rust-lang/rust/issues/42868>",
};
}

declare_lint! {
/// The `order_dependent_trait_objects` lint detects a trait coherency
/// violation that would allow creating two trait impls for the same
Expand Down Expand Up @@ -3266,7 +3225,6 @@ declare_lint_pass! {
CONST_ITEM_MUTATION,
PATTERNS_IN_FNS_WITHOUT_BODY,
MISSING_FRAGMENT_SPECIFIER,
LATE_BOUND_LIFETIME_ARGUMENTS,
ORDER_DEPENDENT_TRAIT_OBJECTS,
COHERENCE_LEAK_CHECK,
DEPRECATED,
Expand Down
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