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Retroactively feature gate ConstArgKind::Path 
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41 files changed

+425
-206
lines changed

‎compiler/rustc_ast_lowering/src/asm.rs

+3-1
Original file line numberDiff line numberDiff line change
@@ -221,7 +221,9 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
221221
let parent_def_id = self.current_def_id_parent;
222222
let node_id = self.next_node_id();
223223
// HACK(min_generic_const_args): see lower_anon_const
224-
if !expr.is_potential_trivial_const_arg() {
224+
if !self.tcx.features().const_arg_path
225+
|| !expr.is_potential_trivial_const_arg()
226+
{
225227
self.create_def(
226228
parent_def_id,
227229
node_id,

‎compiler/rustc_ast_lowering/src/expr.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -387,7 +387,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
387387
let node_id = self.next_node_id();
388388

389389
// HACK(min_generic_const_args): see lower_anon_const
390-
if !arg.is_potential_trivial_const_arg() {
390+
if !self.tcx.features().const_arg_path || !arg.is_potential_trivial_const_arg() {
391391
// Add a definition for the in-band const def.
392392
self.create_def(parent_def_id, node_id, kw::Empty, DefKind::AnonConst, f.span);
393393
}

‎compiler/rustc_ast_lowering/src/lib.rs

+4-3
Original file line numberDiff line numberDiff line change
@@ -2358,7 +2358,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
23582358
span: Span,
23592359
) -> &'hir hir::ConstArg<'hir> {
23602360
let ct_kind = match res {
2361-
Res::Def(DefKind::ConstParam, _) => {
2361+
Res::Def(DefKind::ConstParam, _) if self.tcx.features().const_arg_path => {
23622362
let qpath = self.lower_qpath(
23632363
ty_id,
23642364
&None,
@@ -2433,7 +2433,8 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
24332433
self.resolver.get_partial_res(expr.id).and_then(|partial_res| partial_res.full_res());
24342434
debug!("res={:?}", maybe_res);
24352435
// FIXME(min_generic_const_args): for now we only lower params to ConstArgKind::Path
2436-
if let Some(res) = maybe_res
2436+
if self.tcx.features().const_arg_path
2437+
&& let Some(res) = maybe_res
24372438
&& let Res::Def(DefKind::ConstParam, _) = res
24382439
&& let ExprKind::Path(qself, path) = &expr.kind
24392440
{
@@ -2464,7 +2465,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
24642465
/// See [`hir::ConstArg`] for when to use this function vs
24652466
/// [`Self::lower_anon_const_to_const_arg`].
24662467
fn lower_anon_const_to_anon_const(&mut self, c: &AnonConst) -> &'hir hir::AnonConst {
2467-
if c.value.is_potential_trivial_const_arg() {
2468+
if self.tcx.features().const_arg_path && c.value.is_potential_trivial_const_arg() {
24682469
// HACK(min_generic_const_args): see DefCollector::visit_anon_const
24692470
// Over there, we guess if this is a bare param and only create a def if
24702471
// we think it's not. However we may can guess wrong (see there for example)

‎compiler/rustc_feature/src/unstable.rs

+2
Original file line numberDiff line numberDiff line change
@@ -193,6 +193,8 @@ declare_features! (
193193
(unstable, anonymous_lifetime_in_impl_trait, "1.63.0", None),
194194
/// Allows identifying the `compiler_builtins` crate.
195195
(internal, compiler_builtins, "1.13.0", None),
196+
/// Gating for a new desugaring of const arguments of usages of const parameters
197+
(internal, const_arg_path, "1.81.0", None),
196198
/// Allows writing custom MIR
197199
(internal, custom_mir, "1.65.0", None),
198200
/// Outputs useful `assert!` messages

‎compiler/rustc_middle/src/ty/consts.rs

+22-10
Original file line numberDiff line numberDiff line change
@@ -240,7 +240,7 @@ impl<'tcx> Const<'tcx> {
240240

241241
let ty = tcx.type_of(def).no_bound_vars().expect("const parameter types cannot be generic");
242242

243-
match Self::try_from_lit(tcx, ty, expr) {
243+
match Self::try_from_lit_or_param(tcx, ty, expr) {
244244
Some(v) => v,
245245
None => ty::Const::new_unevaluated(
246246
tcx,
@@ -281,7 +281,11 @@ impl<'tcx> Const<'tcx> {
281281
}
282282

283283
#[instrument(skip(tcx), level = "debug")]
284-
fn try_from_lit(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>, expr: &'tcx hir::Expr<'tcx>) -> Option<Self> {
284+
fn try_from_lit_or_param(
285+
tcx: TyCtxt<'tcx>,
286+
ty: Ty<'tcx>,
287+
expr: &'tcx hir::Expr<'tcx>,
288+
) -> Option<Self> {
285289
// Unwrap a block, so that e.g. `{ P }` is recognised as a parameter. Const arguments
286290
// currently have to be wrapped in curly brackets, so it's necessary to special-case.
287291
let expr = match &expr.kind {
@@ -291,6 +295,22 @@ impl<'tcx> Const<'tcx> {
291295
_ => expr,
292296
};
293297

298+
if let hir::ExprKind::Path(
299+
qpath @ hir::QPath::Resolved(
300+
_,
301+
&hir::Path { res: Res::Def(DefKind::ConstParam, _), .. },
302+
),
303+
) = expr.kind
304+
{
305+
if tcx.features().const_arg_path {
306+
span_bug!(
307+
expr.span,
308+
"try_from_lit: received const param which shouldn't be possible"
309+
);
310+
}
311+
return Some(Const::from_param(tcx, qpath, expr.hir_id));
312+
};
313+
294314
let lit_input = match expr.kind {
295315
hir::ExprKind::Lit(lit) => Some(LitToConstInput { lit: &lit.node, ty, neg: false }),
296316
hir::ExprKind::Unary(hir::UnOp::Neg, expr) => match expr.kind {
@@ -318,14 +338,6 @@ impl<'tcx> Const<'tcx> {
318338
}
319339
}
320340

321-
if let hir::ExprKind::Path(hir::QPath::Resolved(
322-
_,
323-
&hir::Path { res: Res::Def(DefKind::ConstParam, _), .. },
324-
)) = expr.kind
325-
{
326-
span_bug!(expr.span, "try_from_lit: received const param which shouldn't be possible")
327-
}
328-
329341
None
330342
}
331343

‎compiler/rustc_resolve/src/def_collector.rs

+9-7
Original file line numberDiff line numberDiff line change
@@ -314,13 +314,15 @@ impl<'a, 'b, 'tcx> visit::Visitor<'a> for DefCollector<'a, 'b, 'tcx> {
314314
}
315315

316316
fn visit_anon_const(&mut self, constant: &'a AnonConst) {
317-
// HACK(min_generic_const_args): don't create defs for anon consts if we think they will
318-
// later be turned into ConstArgKind::Path's. because this is before resolve is done, we
319-
// may accidentally identify a construction of a unit struct as a param and not create a
320-
// def. we'll then create a def later in ast lowering in this case. the parent of nested
321-
// items will be messed up, but that's ok because there can't be any if we're just looking
322-
// for bare idents.
323-
if constant.value.is_potential_trivial_const_arg() {
317+
if self.resolver.tcx.features().const_arg_path
318+
&& constant.value.is_potential_trivial_const_arg()
319+
{
320+
// HACK(min_generic_const_args): don't create defs for anon consts if we think they will
321+
// later be turned into ConstArgKind::Path's. because this is before resolve is done, we
322+
// may accidentally identify a construction of a unit struct as a param and not create a
323+
// def. we'll then create a def later in ast lowering in this case. the parent of nested
324+
// items will be messed up, but that's ok because there can't be any if we're just looking
325+
// for bare idents.
324326
visit::walk_anon_const(self, constant)
325327
} else {
326328
let def =

‎compiler/rustc_span/src/symbol.rs

+1
Original file line numberDiff line numberDiff line change
@@ -595,6 +595,7 @@ symbols! {
595595
conservative_impl_trait,
596596
console,
597597
const_allocate,
598+
const_arg_path,
598599
const_async_blocks,
599600
const_closures,
600601
const_compare_raw_pointers,

‎tests/crashes/127972.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -1,5 +1,5 @@
11
//@ known-bug: #127962
2-
#![feature(generic_const_exprs)]
2+
#![feature(generic_const_exprs, const_arg_path)]
33

44
fn zero_init<const usize: usize>() -> Substs1<{ (N) }> {
55
Substs1([0; { (usize) }])

‎tests/crashes/128016.rs

-10
This file was deleted.

‎tests/ui-fulldeps/stable-mir/check_instance.rs

+6-4
Original file line numberDiff line numberDiff line change
@@ -17,12 +17,14 @@ extern crate rustc_driver;
1717
extern crate rustc_interface;
1818
extern crate stable_mir;
1919

20-
use mir::{mono::Instance, TerminatorKind::*};
20+
use std::io::Write;
21+
use std::ops::ControlFlow;
22+
23+
use mir::mono::Instance;
24+
use mir::TerminatorKind::*;
2125
use rustc_smir::rustc_internal;
2226
use stable_mir::ty::{RigidTy, TyKind};
2327
use stable_mir::*;
24-
use std::io::Write;
25-
use std::ops::ControlFlow;
2628

2729
const CRATE_NAME: &str = "input";
2830

@@ -33,7 +35,7 @@ fn test_stable_mir() -> ControlFlow<()> {
3335
// Get all items and split generic vs monomorphic items.
3436
let (generic, mono): (Vec<_>, Vec<_>) =
3537
items.into_iter().partition(|item| item.requires_monomorphization());
36-
assert_eq!(mono.len(), 3, "Expected 3 mono functions");
38+
assert_eq!(mono.len(), 4, "Expected 3 mono functions");
3739
assert_eq!(generic.len(), 2, "Expected 2 generic functions");
3840

3941
// For all monomorphic items, get the correspondent instances.

‎tests/ui/coherence/negative-coherence/generic_const_type_mismatch.rs

+2
Original file line numberDiff line numberDiff line change
@@ -5,7 +5,9 @@
55
#![feature(with_negative_coherence)]
66
trait Trait {}
77
impl<const N: u8> Trait for [(); N] {}
8+
//~^ ERROR: mismatched types
89
impl<const N: i8> Trait for [(); N] {}
910
//~^ ERROR: conflicting implementations of trait `Trait`
11+
//~| ERROR: mismatched types
1012

1113
fn main() {}

‎tests/ui/coherence/negative-coherence/generic_const_type_mismatch.stderr

+17-3
Original file line numberDiff line numberDiff line change
@@ -1,11 +1,25 @@
11
error[E0119]: conflicting implementations of trait `Trait` for type `[(); _]`
2-
--> $DIR/generic_const_type_mismatch.rs:8:1
2+
--> $DIR/generic_const_type_mismatch.rs:9:1
33
|
44
LL | impl<const N: u8> Trait for [(); N] {}
55
| ----------------------------------- first implementation here
6+
LL |
67
LL | impl<const N: i8> Trait for [(); N] {}
78
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ conflicting implementation for `[(); _]`
89

9-
error: aborting due to 1 previous error
10+
error[E0308]: mismatched types
11+
--> $DIR/generic_const_type_mismatch.rs:7:34
12+
|
13+
LL | impl<const N: u8> Trait for [(); N] {}
14+
| ^ expected `usize`, found `u8`
15+
16+
error[E0308]: mismatched types
17+
--> $DIR/generic_const_type_mismatch.rs:9:34
18+
|
19+
LL | impl<const N: i8> Trait for [(); N] {}
20+
| ^ expected `usize`, found `i8`
21+
22+
error: aborting due to 3 previous errors
1023

11-
For more information about this error, try `rustc --explain E0119`.
24+
Some errors have detailed explanations: E0119, E0308.
25+
For more information about an error, try `rustc --explain E0119`.

‎tests/ui/const-generics/bad-subst-const-kind.rs

+1
Original file line numberDiff line numberDiff line change
@@ -7,6 +7,7 @@ trait Q {
77

88
impl<const N: u64> Q for [u8; N] {
99
//~^ ERROR: the constant `N` is not of type `usize`
10+
//~| ERROR: mismatched types
1011
const ASSOC: usize = 1;
1112
}
1213

‎tests/ui/const-generics/bad-subst-const-kind.stderr

+9-2
Original file line numberDiff line numberDiff line change
@@ -5,7 +5,7 @@ LL | impl<const N: u64> Q for [u8; N] {
55
| ^^^^^^^ expected `usize`, found `u64`
66

77
error: the constant `13` is not of type `u64`
8-
--> $DIR/bad-subst-const-kind.rs:13:24
8+
--> $DIR/bad-subst-const-kind.rs:14:24
99
|
1010
LL | pub fn test() -> [u8; <[u8; 13] as Q>::ASSOC] {
1111
| ^^^^^^^^ expected `u64`, found `usize`
@@ -18,5 +18,12 @@ LL | impl<const N: u64> Q for [u8; N] {
1818
| |
1919
| unsatisfied trait bound introduced here
2020

21-
error: aborting due to 2 previous errors
21+
error[E0308]: mismatched types
22+
--> $DIR/bad-subst-const-kind.rs:8:31
23+
|
24+
LL | impl<const N: u64> Q for [u8; N] {
25+
| ^ expected `usize`, found `u64`
26+
27+
error: aborting due to 3 previous errors
2228

29+
For more information about this error, try `rustc --explain E0308`.

‎tests/ui/const-generics/early/trivial-const-arg-macro-nested.rs

+21
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,21 @@
1+
//@ check-pass
2+
3+
// This is a regression test for #128016.
4+
5+
macro_rules! len_inner {
6+
() => {
7+
BAR
8+
};
9+
}
10+
11+
macro_rules! len {
12+
() => {
13+
len_inner!()
14+
};
15+
}
16+
17+
const BAR: usize = 0;
18+
19+
fn main() {
20+
let val: [bool; len!()] = [];
21+
}

‎tests/ui/const-generics/early/trivial-const-arg-macro-param.rs

+13
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,13 @@
1+
//@ check-pass
2+
3+
macro_rules! len {
4+
($x:ident) => {
5+
$x
6+
};
7+
}
8+
9+
fn bar<const N: usize>() {
10+
let val: [bool; len!(N)] = [true; N];
11+
}
12+
13+
fn main() {}

‎tests/ui/const-generics/early/trivial-const-arg-macro-res-error.rs

+13
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,13 @@
1+
// This is a regression test for #128016.
2+
3+
macro_rules! len {
4+
() => {
5+
target
6+
//~^ ERROR cannot find value `target`
7+
};
8+
}
9+
10+
fn main() {
11+
let val: [str; len!()] = [];
12+
//~^ ERROR the size for values
13+
}

‎tests/ui/const-generics/early/trivial-const-arg-macro-res-error.stderr

+24
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,24 @@
1+
error[E0425]: cannot find value `target` in this scope
2+
--> $DIR/trivial-const-arg-macro-res-error.rs:5:9
3+
|
4+
LL | target
5+
| ^^^^^^ not found in this scope
6+
...
7+
LL | let val: [str; len!()] = [];
8+
| ------ in this macro invocation
9+
|
10+
= note: this error originates in the macro `len` (in Nightly builds, run with -Z macro-backtrace for more info)
11+
12+
error[E0277]: the size for values of type `str` cannot be known at compilation time
13+
--> $DIR/trivial-const-arg-macro-res-error.rs:11:14
14+
|
15+
LL | let val: [str; len!()] = [];
16+
| ^^^^^^^^^^^^^ doesn't have a size known at compile-time
17+
|
18+
= help: the trait `Sized` is not implemented for `str`
19+
= note: slice and array elements must have `Sized` type
20+
21+
error: aborting due to 2 previous errors
22+
23+
Some errors have detailed explanations: E0277, E0425.
24+
For more information about an error, try `rustc --explain E0277`.

‎tests/ui/const-generics/early/trivial-const-arg-macro.rs

+15
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,15 @@
1+
//@ check-pass
2+
3+
// This is a regression test for #128016.
4+
5+
macro_rules! len {
6+
() => {
7+
BAR
8+
};
9+
}
10+
11+
const BAR: usize = 0;
12+
13+
fn main() {
14+
let val: [bool; len!()] = [];
15+
}

‎tests/ui/const-generics/generic_const_exprs/type_mismatch.rs

+1
Original file line numberDiff line numberDiff line change
@@ -8,6 +8,7 @@ trait Q {
88
impl<const N: u64> Q for [u8; N] {}
99
//~^ ERROR not all trait items implemented
1010
//~| ERROR the constant `N` is not of type `usize`
11+
//~| ERROR mismatched types
1112

1213
pub fn q_user() -> [u8; <[u8; 13] as Q>::ASSOC] {}
1314
//~^ ERROR the constant `13` is not of type `u64`

‎tests/ui/const-generics/generic_const_exprs/type_mismatch.stderr

+9-3
Original file line numberDiff line numberDiff line change
@@ -14,7 +14,7 @@ LL | impl<const N: u64> Q for [u8; N] {}
1414
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ missing `ASSOC` in implementation
1515

1616
error: the constant `13` is not of type `u64`
17-
--> $DIR/type_mismatch.rs:12:26
17+
--> $DIR/type_mismatch.rs:13:26
1818
|
1919
LL | pub fn q_user() -> [u8; <[u8; 13] as Q>::ASSOC] {}
2020
| ^^^^^^^^ expected `u64`, found `usize`
@@ -28,14 +28,20 @@ LL | impl<const N: u64> Q for [u8; N] {}
2828
| unsatisfied trait bound introduced here
2929

3030
error[E0308]: mismatched types
31-
--> $DIR/type_mismatch.rs:12:20
31+
--> $DIR/type_mismatch.rs:13:20
3232
|
3333
LL | pub fn q_user() -> [u8; <[u8; 13] as Q>::ASSOC] {}
3434
| ------ ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ expected `[u8; <[u8; 13] as Q>::ASSOC]`, found `()`
3535
| |
3636
| implicitly returns `()` as its body has no tail or `return` expression
3737

38-
error: aborting due to 4 previous errors
38+
error[E0308]: mismatched types
39+
--> $DIR/type_mismatch.rs:8:31
40+
|
41+
LL | impl<const N: u64> Q for [u8; N] {}
42+
| ^ expected `usize`, found `u64`
43+
44+
error: aborting due to 5 previous errors
3945

4046
Some errors have detailed explanations: E0046, E0308.
4147
For more information about an error, try `rustc --explain E0046`.

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