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fmeasefmease
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[detect escaping gen params]
1 parent 83ab26f commit cca22f2

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5 files changed

+189
-4
lines changed

5 files changed

+189
-4
lines changed

‎compiler/rustc_hir_analysis/messages.ftl

+14
Original file line numberDiff line numberDiff line change
@@ -285,6 +285,20 @@ hir_analysis_only_current_traits_primitive = only traits defined in the current
285285
286286
hir_analysis_only_current_traits_ty = `{$ty}` is not defined in the current crate
287287
288+
hir_analysis_param_in_ty_of_assoc_const =
289+
the type of the associated constant `{$assoc_const}` must not depend on {$synthetic ->
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[true] `impl Trait`
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*[false] generic parameters
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}
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.label = its type must not depend on {$synthetic ->
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[true] `impl Trait`
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*[false] the {$param_kind} parameter `{$param_name}`
296+
}
297+
.param_defined_here_label = {$synthetic ->
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[true] the `impl Trait` is specified here
299+
*[false] the {$param_kind} parameter `{$param_name}` is defined here
300+
}
301+
288302
hir_analysis_paren_sugar_attribute = the `#[rustc_paren_sugar]` attribute is a temporary means of controlling which traits can use parenthetical notation
289303
.help = add `#![feature(unboxed_closures)]` to the crate attributes to use it
290304

‎compiler/rustc_hir_analysis/src/collect/type_of.rs

+88-4
Original file line numberDiff line numberDiff line change
@@ -1,3 +1,6 @@
1+
use std::ops::ControlFlow;
2+
3+
use rustc_data_structures::fx::FxIndexSet;
14
use rustc_errors::{Applicability, StashKey};
25
use rustc_hir as hir;
36
use rustc_hir::def_id::{DefId, LocalDefId};
@@ -7,7 +10,8 @@ use rustc_middle::ty::print::with_forced_trimmed_paths;
710
use rustc_middle::ty::util::IntTypeExt;
811
use rustc_middle::ty::{self, ImplTraitInTraitData, IsSuggestable, Ty, TyCtxt, TypeVisitableExt};
912
use rustc_span::symbol::Ident;
10-
use rustc_span::{Span, DUMMY_SP};
13+
use rustc_span::{ErrorGuaranteed, Span, Symbol, DUMMY_SP};
14+
use rustc_type_ir::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor};
1115

1216
use super::ItemCtxt;
1317
use super::{bad_placeholder, is_suggestable_infer_ty};
@@ -66,10 +70,24 @@ fn anon_const_type_of<'tcx>(tcx: TyCtxt<'tcx>, def_id: LocalDefId) -> Ty<'tcx> {
6670
.expect("const parameter types cannot be generic");
6771
}
6872

69-
Node::TypeBinding(&TypeBinding { hir_id, .. }) => {
70-
// FIXME(fmease): Reject “escaping” early-bound generic parameters.
73+
Node::TypeBinding(&TypeBinding { hir_id, ident, .. }) => {
74+
let ty = tcx.type_of_assoc_const_binding(hir_id);
75+
76+
// FIXME(const_generics): Support generic const generics.
77+
let Some(ty) = ty.no_bound_vars() else {
78+
// We can't possibly catch this in the resolver, therefore we need to handle it here.
79+
let guar = report_assoc_const_depends_on_generic_params(
80+
tcx,
81+
ident,
82+
// FIXME(fmease): Improve this situation:
83+
ty.skip_binder().skip_binder(),
84+
hir_id,
85+
);
86+
return Ty::new_error(tcx, guar);
87+
};
88+
7189
// FIXME(fmease): Reject escaping late-bound vars.
72-
return tcx.type_of_assoc_const_binding(hir_id).skip_binder().skip_binder();
90+
return ty.skip_binder();
7391
}
7492

7593
// This match arm is for when the def_id appears in a GAT whose
@@ -293,6 +311,72 @@ pub(super) fn type_of_assoc_const_binding<'tcx>(
293311
ty::EarlyBinder::bind(ty::Binder::dummy(Ty::new_error(tcx, guar)))
294312
}
295313

314+
fn report_assoc_const_depends_on_generic_params<'tcx>(
315+
tcx: TyCtxt<'tcx>,
316+
assoc_const: Ident,
317+
ty: Ty<'tcx>,
318+
hir_id: HirId,
319+
) -> ErrorGuaranteed {
320+
let body_owner = tcx.hir().enclosing_body_owner(hir_id);
321+
let generics = tcx.generics_of(body_owner);
322+
323+
let mut finder = GenericParamFinder { params: Default::default() };
324+
ty.visit_with(&mut finder);
325+
let mut guar = None;
326+
for (param_index, param_name) in finder.params {
327+
let param_def = generics.param_at(param_index as _, tcx);
328+
guar.get_or_insert(tcx.dcx().emit_err(crate::errors::ParamInTyOfAssocConst {
329+
span: assoc_const.span,
330+
assoc_const,
331+
param_name,
332+
param_kind: match &param_def.kind {
333+
ty::GenericParamDefKind::Lifetime => "lifetime",
334+
ty::GenericParamDefKind::Type { .. } => "type",
335+
ty::GenericParamDefKind::Const { .. } => "const",
336+
},
337+
synthetic: param_def.kind.is_synthetic(),
338+
param_defined_here_label: tcx.def_ident_span(param_def.def_id).unwrap(),
339+
}));
340+
}
341+
342+
struct GenericParamFinder {
343+
params: FxIndexSet<(u32, Symbol)>,
344+
}
345+
346+
impl<'tcx> TypeVisitor<TyCtxt<'tcx>> for GenericParamFinder {
347+
type BreakTy = !;
348+
349+
fn visit_ty(&mut self, ty: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
350+
if let ty::Param(param) = ty.kind() {
351+
self.params.insert((param.index, param.name));
352+
return ControlFlow::Continue(());
353+
}
354+
355+
ty.super_visit_with(self)
356+
}
357+
358+
fn visit_region(&mut self, re: ty::Region<'tcx>) -> ControlFlow<Self::BreakTy> {
359+
if let ty::ReEarlyParam(param) = re.kind() {
360+
self.params.insert((param.index, param.name));
361+
return ControlFlow::Continue(());
362+
}
363+
364+
ControlFlow::Continue(())
365+
}
366+
367+
fn visit_const(&mut self, ct: ty::Const<'tcx>) -> ControlFlow<Self::BreakTy> {
368+
if let ty::ConstKind::Param(param) = ct.kind() {
369+
self.params.insert((param.index, param.name));
370+
return ControlFlow::Continue(());
371+
}
372+
373+
ct.super_visit_with(self)
374+
}
375+
}
376+
377+
guar.unwrap_or_else(|| bug!("failed to find gen params in ty even though `ty.has_param()`"))
378+
}
379+
296380
fn get_path_containing_arg_in_pat<'hir>(
297381
pat: &'hir hir::Pat<'hir>,
298382
arg_id: HirId,

‎compiler/rustc_hir_analysis/src/errors.rs

+14
Original file line numberDiff line numberDiff line change
@@ -254,6 +254,20 @@ pub struct AssocTypeBindingNotAllowed {
254254
pub fn_trait_expansion: Option<ParenthesizedFnTraitExpansion>,
255255
}
256256

257+
#[derive(Diagnostic)]
258+
#[diag(hir_analysis_param_in_ty_of_assoc_const)]
259+
pub(crate) struct ParamInTyOfAssocConst {
260+
#[primary_span]
261+
#[label]
262+
pub span: Span,
263+
pub assoc_const: Ident,
264+
pub param_name: Symbol,
265+
pub param_kind: &'static str,
266+
pub synthetic: bool,
267+
#[label(hir_analysis_param_defined_here_label)]
268+
pub param_defined_here_label: Span,
269+
}
270+
257271
#[derive(Subdiagnostic)]
258272
#[help(hir_analysis_parenthesized_fn_trait_expansion)]
259273
pub struct ParenthesizedFnTraitExpansion {

‎tests/ui/associated-consts/assoc-const-eq-param-in-ty.rs

+34
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,34 @@
1+
// Regression test for issue #108271.
2+
// Detect and reject generic params in the type of assoc consts used in an equality bound.
3+
#![feature(associated_const_equality)]
4+
5+
trait Trait<'a, T, const N: usize> {
6+
const K: &'a [T; N];
7+
}
8+
9+
fn take0<'r, A, const Q: usize>(_: impl Trait<'r, A, Q, K = { loop {} }>) {}
10+
//~^ ERROR the type of the associated constant `K` must not depend on generic parameters
11+
//~| NOTE its type must not depend on the lifetime parameter `'r`
12+
//~| NOTE the lifetime parameter `'r` is defined here
13+
//~| ERROR the type of the associated constant `K` must not depend on generic parameters
14+
//~| NOTE its type must not depend on the type parameter `A`
15+
//~| NOTE the type parameter `A` is defined here
16+
//~| ERROR the type of the associated constant `K` must not depend on generic parameters
17+
//~| NOTE its type must not depend on the const parameter `Q`
18+
//~| NOTE the const parameter `Q` is defined here
19+
20+
trait Project {
21+
const SELF: Self;
22+
}
23+
24+
fn take1(_: impl Project<SELF = {}>) {}
25+
//~^ ERROR the type of the associated constant `SELF` must not depend on `impl Trait`
26+
//~| NOTE its type must not depend on `impl Trait`
27+
//~| NOTE the `impl Trait` is specified here
28+
29+
fn take2<P: Project<SELF = {}>>(_: P) {}
30+
//~^ ERROR the type of the associated constant `SELF` must not depend on generic parameters
31+
//~| NOTE its type must not depend on the type parameter `P`
32+
//~| NOTE the type parameter `P` is defined here
33+
34+
fn main() {}

‎tests/ui/associated-consts/assoc-const-eq-param-in-ty.stderr

+39
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,39 @@
1+
error: the type of the associated constant `K` must not depend on generic parameters
2+
--> $DIR/assoc-const-eq-param-in-ty.rs:9:57
3+
|
4+
LL | fn take0<'r, A, const Q: usize>(_: impl Trait<'r, A, Q, K = { loop {} }>) {}
5+
| -- the lifetime parameter `'r` is defined here ^ its type must not depend on the lifetime parameter `'r`
6+
7+
error: the type of the associated constant `K` must not depend on generic parameters
8+
--> $DIR/assoc-const-eq-param-in-ty.rs:9:57
9+
|
10+
LL | fn take0<'r, A, const Q: usize>(_: impl Trait<'r, A, Q, K = { loop {} }>) {}
11+
| - the type parameter `A` is defined here ^ its type must not depend on the type parameter `A`
12+
13+
error: the type of the associated constant `K` must not depend on generic parameters
14+
--> $DIR/assoc-const-eq-param-in-ty.rs:9:57
15+
|
16+
LL | fn take0<'r, A, const Q: usize>(_: impl Trait<'r, A, Q, K = { loop {} }>) {}
17+
| - ^ its type must not depend on the const parameter `Q`
18+
| |
19+
| the const parameter `Q` is defined here
20+
21+
error: the type of the associated constant `SELF` must not depend on `impl Trait`
22+
--> $DIR/assoc-const-eq-param-in-ty.rs:24:26
23+
|
24+
LL | fn take1(_: impl Project<SELF = {}>) {}
25+
| -------------^^^^------
26+
| | |
27+
| | its type must not depend on `impl Trait`
28+
| the `impl Trait` is specified here
29+
30+
error: the type of the associated constant `SELF` must not depend on generic parameters
31+
--> $DIR/assoc-const-eq-param-in-ty.rs:29:21
32+
|
33+
LL | fn take2<P: Project<SELF = {}>>(_: P) {}
34+
| - ^^^^ its type must not depend on the type parameter `P`
35+
| |
36+
| the type parameter `P` is defined here
37+
38+
error: aborting due to 5 previous errors
39+

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