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Fix pretty printing of unsafe binders
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5 files changed

+131
-42
lines changed

5 files changed

+131
-42
lines changed

‎compiler/rustc_middle/src/ty/print/pretty.rs‎

Lines changed: 80 additions & 37 deletions
Original file line numberDiff line numberDiff line change
@@ -133,6 +133,20 @@ pub macro with_no_queries($e:expr) {{
133133
))
134134
}}
135135

136+
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
137+
pub enum WrapBinderMode {
138+
ForAll,
139+
Unsafe,
140+
}
141+
impl WrapBinderMode {
142+
pub fn start_str(self) -> &'static str {
143+
match self {
144+
WrapBinderMode::ForAll => "for<",
145+
WrapBinderMode::Unsafe => "unsafe<",
146+
}
147+
}
148+
}
149+
136150
/// The "region highlights" are used to control region printing during
137151
/// specific error messages. When a "region highlight" is enabled, it
138152
/// gives an alternate way to print specific regions. For now, we
@@ -219,7 +233,11 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
219233
self.print_def_path(def_id, args)
220234
}
221235

222-
fn in_binder<T>(&mut self, value: &ty::Binder<'tcx, T>) -> Result<(), PrintError>
236+
fn in_binder<T>(
237+
&mut self,
238+
value: &ty::Binder<'tcx, T>,
239+
_mode: WrapBinderMode,
240+
) -> Result<(), PrintError>
223241
where
224242
T: Print<'tcx, Self> + TypeFoldable<TyCtxt<'tcx>>,
225243
{
@@ -229,6 +247,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
229247
fn wrap_binder<T, F: FnOnce(&T, &mut Self) -> Result<(), fmt::Error>>(
230248
&mut self,
231249
value: &ty::Binder<'tcx, T>,
250+
_mode: WrapBinderMode,
232251
f: F,
233252
) -> Result<(), PrintError>
234253
where
@@ -703,8 +722,9 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
703722
}
704723
ty::FnPtr(ref sig_tys, hdr) => p!(print(sig_tys.with(hdr))),
705724
ty::UnsafeBinder(ref bound_ty) => {
706-
// FIXME(unsafe_binders): Make this print `unsafe<>` rather than `for<>`.
707-
self.wrap_binder(bound_ty, |ty, cx| cx.pretty_print_type(*ty))?;
725+
self.wrap_binder(bound_ty, WrapBinderMode::Unsafe, |ty, cx| {
726+
cx.pretty_print_type(*ty)
727+
})?;
708728
}
709729
ty::Infer(infer_ty) => {
710730
if self.should_print_verbose() {
@@ -1067,29 +1087,33 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
10671087
};
10681088

10691089
if let Some(return_ty) = entry.return_ty {
1070-
self.wrap_binder(&bound_args_and_self_ty, |(args, _), cx| {
1071-
define_scoped_cx!(cx);
1072-
p!(write("{}", tcx.item_name(trait_def_id)));
1073-
p!("(");
1074-
1075-
for (idx, ty) in args.iter().enumerate() {
1076-
if idx > 0 {
1077-
p!(", ");
1090+
self.wrap_binder(
1091+
&bound_args_and_self_ty,
1092+
WrapBinderMode::ForAll,
1093+
|(args, _), cx| {
1094+
define_scoped_cx!(cx);
1095+
p!(write("{}", tcx.item_name(trait_def_id)));
1096+
p!("(");
1097+
1098+
for (idx, ty) in args.iter().enumerate() {
1099+
if idx > 0 {
1100+
p!(", ");
1101+
}
1102+
p!(print(ty));
10781103
}
1079-
p!(print(ty));
1080-
}
10811104

1082-
p!(")");
1083-
if let Some(ty) = return_ty.skip_binder().as_type() {
1084-
if !ty.is_unit() {
1085-
p!(" -> ", print(return_ty));
1105+
p!(")");
1106+
if let Some(ty) = return_ty.skip_binder().as_type() {
1107+
if !ty.is_unit() {
1108+
p!(" -> ", print(return_ty));
1109+
}
10861110
}
1087-
}
1088-
p!(write("{}", if paren_needed { ")" } else { "" }));
1111+
p!(write("{}", if paren_needed { ")" } else { "" }));
10891112

1090-
first = false;
1091-
Ok(())
1092-
})?;
1113+
first = false;
1114+
Ok(())
1115+
},
1116+
)?;
10931117
} else {
10941118
// Otherwise, render this like a regular trait.
10951119
traits.insert(
@@ -1110,7 +1134,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
11101134
for (trait_pred, assoc_items) in traits {
11111135
write!(self, "{}", if first { "" } else { " + " })?;
11121136

1113-
self.wrap_binder(&trait_pred, |trait_pred, cx| {
1137+
self.wrap_binder(&trait_pred, WrapBinderMode::ForAll, |trait_pred, cx| {
11141138
define_scoped_cx!(cx);
11151139

11161140
if trait_pred.polarity == ty::PredicatePolarity::Negative {
@@ -1302,7 +1326,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
13021326
let mut first = true;
13031327

13041328
if let Some(bound_principal) = predicates.principal() {
1305-
self.wrap_binder(&bound_principal, |principal, cx| {
1329+
self.wrap_binder(&bound_principal, WrapBinderMode::ForAll, |principal, cx| {
13061330
define_scoped_cx!(cx);
13071331
p!(print_def_path(principal.def_id, &[]));
13081332

@@ -1927,7 +1951,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
19271951
let kind = closure.kind_ty().to_opt_closure_kind().unwrap_or(ty::ClosureKind::Fn);
19281952

19291953
write!(self, "impl ")?;
1930-
self.wrap_binder(&sig, |sig, cx| {
1954+
self.wrap_binder(&sig, WrapBinderMode::ForAll, |sig, cx| {
19311955
define_scoped_cx!(cx);
19321956

19331957
p!(write("{kind}("));
@@ -2367,22 +2391,27 @@ impl<'tcx> PrettyPrinter<'tcx> for FmtPrinter<'_, 'tcx> {
23672391
Ok(())
23682392
}
23692393

2370-
fn in_binder<T>(&mut self, value: &ty::Binder<'tcx, T>) -> Result<(), PrintError>
2394+
fn in_binder<T>(
2395+
&mut self,
2396+
value: &ty::Binder<'tcx, T>,
2397+
mode: WrapBinderMode,
2398+
) -> Result<(), PrintError>
23712399
where
23722400
T: Print<'tcx, Self> + TypeFoldable<TyCtxt<'tcx>>,
23732401
{
2374-
self.pretty_in_binder(value)
2402+
self.pretty_in_binder(value, mode)
23752403
}
23762404

23772405
fn wrap_binder<T, C: FnOnce(&T, &mut Self) -> Result<(), PrintError>>(
23782406
&mut self,
23792407
value: &ty::Binder<'tcx, T>,
2408+
mode: WrapBinderMode,
23802409
f: C,
23812410
) -> Result<(), PrintError>
23822411
where
23832412
T: TypeFoldable<TyCtxt<'tcx>>,
23842413
{
2385-
self.pretty_wrap_binder(value, f)
2414+
self.pretty_wrap_binder(value, mode, f)
23862415
}
23872416

23882417
fn typed_value(
@@ -2632,6 +2661,7 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
26322661
pub fn name_all_regions<T>(
26332662
&mut self,
26342663
value: &ty::Binder<'tcx, T>,
2664+
mode: WrapBinderMode,
26352665
) -> Result<(T, UnordMap<ty::BoundRegion, ty::Region<'tcx>>), fmt::Error>
26362666
where
26372667
T: TypeFoldable<TyCtxt<'tcx>>,
@@ -2705,9 +2735,13 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
27052735
// anyways.
27062736
let (new_value, map) = if self.should_print_verbose() {
27072737
for var in value.bound_vars().iter() {
2708-
start_or_continue(self, "for<", ", ");
2738+
start_or_continue(self, mode.start_str(), ", ");
27092739
write!(self, "{var:?}")?;
27102740
}
2741+
// Unconditionally render `unsafe<>`.
2742+
if value.bound_vars().is_empty() && mode == WrapBinderMode::Unsafe {
2743+
start_or_continue(self, mode.start_str(), "");
2744+
}
27112745
start_or_continue(self, "", "> ");
27122746
(value.clone().skip_binder(), UnordMap::default())
27132747
} else {
@@ -2772,8 +2806,9 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
27722806
}
27732807
};
27742808

2775-
if !trim_path {
2776-
start_or_continue(self, "for<", ", ");
2809+
// Unconditionally render `unsafe<>`.
2810+
if !trim_path || mode == WrapBinderMode::Unsafe {
2811+
start_or_continue(self, mode.start_str(), ", ");
27772812
do_continue(self, name);
27782813
}
27792814
ty::Region::new_bound(tcx, ty::INNERMOST, ty::BoundRegion { var: br.var, kind })
@@ -2786,9 +2821,12 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
27862821
};
27872822
let new_value = value.clone().skip_binder().fold_with(&mut folder);
27882823
let region_map = folder.region_map;
2789-
if !trim_path {
2790-
start_or_continue(self, "", "> ");
2824+
2825+
if mode == WrapBinderMode::Unsafe && region_map.is_empty() {
2826+
start_or_continue(self, mode.start_str(), "");
27912827
}
2828+
start_or_continue(self, "", "> ");
2829+
27922830
(new_value, region_map)
27932831
};
27942832

@@ -2797,12 +2835,16 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
27972835
Ok((new_value, map))
27982836
}
27992837

2800-
pub fn pretty_in_binder<T>(&mut self, value: &ty::Binder<'tcx, T>) -> Result<(), fmt::Error>
2838+
pub fn pretty_in_binder<T>(
2839+
&mut self,
2840+
value: &ty::Binder<'tcx, T>,
2841+
mode: WrapBinderMode,
2842+
) -> Result<(), fmt::Error>
28012843
where
28022844
T: Print<'tcx, Self> + TypeFoldable<TyCtxt<'tcx>>,
28032845
{
28042846
let old_region_index = self.region_index;
2805-
let (new_value, _) = self.name_all_regions(value)?;
2847+
let (new_value, _) = self.name_all_regions(value, mode)?;
28062848
new_value.print(self)?;
28072849
self.region_index = old_region_index;
28082850
self.binder_depth -= 1;
@@ -2812,13 +2854,14 @@ impl<'tcx> FmtPrinter<'_, 'tcx> {
28122854
pub fn pretty_wrap_binder<T, C: FnOnce(&T, &mut Self) -> Result<(), fmt::Error>>(
28132855
&mut self,
28142856
value: &ty::Binder<'tcx, T>,
2857+
mode: WrapBinderMode,
28152858
f: C,
28162859
) -> Result<(), fmt::Error>
28172860
where
28182861
T: TypeFoldable<TyCtxt<'tcx>>,
28192862
{
28202863
let old_region_index = self.region_index;
2821-
let (new_value, _) = self.name_all_regions(value)?;
2864+
let (new_value, _) = self.name_all_regions(value, mode)?;
28222865
f(&new_value, self)?;
28232866
self.region_index = old_region_index;
28242867
self.binder_depth -= 1;
@@ -2877,7 +2920,7 @@ where
28772920
T: Print<'tcx, P> + TypeFoldable<TyCtxt<'tcx>>,
28782921
{
28792922
fn print(&self, cx: &mut P) -> Result<(), PrintError> {
2880-
cx.in_binder(self)
2923+
cx.in_binder(self, WrapBinderMode::ForAll)
28812924
}
28822925
}
28832926

‎compiler/rustc_symbol_mangling/src/v0.rs‎

Lines changed: 4 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -12,7 +12,7 @@ use rustc_hir::def_id::{CrateNum, DefId};
1212
use rustc_hir::definitions::{DefPathData, DisambiguatedDefPathData};
1313
use rustc_middle::bug;
1414
use rustc_middle::ty::layout::IntegerExt;
15-
use rustc_middle::ty::print::{Print, PrintError, Printer};
15+
use rustc_middle::ty::print::{Print, PrintError, Printer, WrapBinderMode};
1616
use rustc_middle::ty::{
1717
self, FloatTy, GenericArg, GenericArgKind, Instance, IntTy, ReifyReason, Ty, TyCtxt,
1818
TypeVisitable, TypeVisitableExt, UintTy,
@@ -172,6 +172,7 @@ impl<'tcx> SymbolMangler<'tcx> {
172172
fn in_binder<T>(
173173
&mut self,
174174
value: &ty::Binder<'tcx, T>,
175+
_mode: WrapBinderMode,
175176
print_value: impl FnOnce(&mut Self, &T) -> Result<(), PrintError>,
176177
) -> Result<(), PrintError>
177178
where
@@ -471,7 +472,7 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
471472
ty::FnPtr(sig_tys, hdr) => {
472473
let sig = sig_tys.with(hdr);
473474
self.push("F");
474-
self.in_binder(&sig, |cx, sig| {
475+
self.in_binder(&sig, WrapBinderMode::ForAll, |cx, sig| {
475476
if sig.safety.is_unsafe() {
476477
cx.push("U");
477478
}
@@ -554,7 +555,7 @@ impl<'tcx> Printer<'tcx> for SymbolMangler<'tcx> {
554555
// [<Trait> [{<Projection>}]] [{<Auto>}]
555556
// Since any predicates after the first one shouldn't change the binders,
556557
// just put them all in the binders of the first.
557-
self.in_binder(&predicates[0], |cx, _| {
558+
self.in_binder(&predicates[0], WrapBinderMode::ForAll, |cx, _| {
558559
for predicate in predicates.iter() {
559560
// It would be nice to be able to validate bound vars here, but
560561
// projections can actually include bound vars from super traits

‎compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs‎

Lines changed: 4 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -65,7 +65,9 @@ use rustc_middle::bug;
6565
use rustc_middle::dep_graph::DepContext;
6666
use rustc_middle::traits::PatternOriginExpr;
6767
use rustc_middle::ty::error::{ExpectedFound, TypeError, TypeErrorToStringExt};
68-
use rustc_middle::ty::print::{PrintError, PrintTraitRefExt as _, with_forced_trimmed_paths};
68+
use rustc_middle::ty::print::{
69+
PrintError, PrintTraitRefExt as _, WrapBinderMode, with_forced_trimmed_paths,
70+
};
6971
use rustc_middle::ty::{
7072
self, List, ParamEnv, Region, Ty, TyCtxt, TypeFoldable, TypeSuperVisitable, TypeVisitable,
7173
TypeVisitableExt,
@@ -835,7 +837,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
835837
let get_lifetimes = |sig| {
836838
use rustc_hir::def::Namespace;
837839
let (sig, reg) = ty::print::FmtPrinter::new(self.tcx, Namespace::TypeNS)
838-
.name_all_regions(sig)
840+
.name_all_regions(sig, WrapBinderMode::ForAll)
839841
.unwrap();
840842
let lts: Vec<String> =
841843
reg.into_items().map(|(_, kind)| kind.to_string()).into_sorted_stable_ord();

‎tests/ui/unsafe-binders/type-mismatch.rs‎

Lines changed: 9 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,9 @@
1+
#![feature(unsafe_binders)]
2+
//~^ WARN the feature `unsafe_binders` is incomplete
3+
4+
fn main() {
5+
let x: unsafe<> i32 = 0;
6+
//~^ ERROR mismatched types
7+
let x: unsafe<'a> &'a i32 = &0;
8+
//~^ ERROR mismatched types
9+
}

‎tests/ui/unsafe-binders/type-mismatch.stderr‎

Lines changed: 34 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,34 @@
1+
warning: the feature `unsafe_binders` is incomplete and may not be safe to use and/or cause compiler crashes
2+
--> $DIR/type-mismatch.rs:1:12
3+
|
4+
LL | #![feature(unsafe_binders)]
5+
| ^^^^^^^^^^^^^^
6+
|
7+
= note: see issue #130516 <https://github.com/rust-lang/rust/issues/130516> for more information
8+
= note: `#[warn(incomplete_features)]` on by default
9+
10+
error[E0308]: mismatched types
11+
--> $DIR/type-mismatch.rs:5:27
12+
|
13+
LL | let x: unsafe<> i32 = 0;
14+
| ------------ ^ expected `unsafe<> i32`, found integer
15+
| |
16+
| expected due to this
17+
|
18+
= note: expected unsafe binder `unsafe<> i32`
19+
found type `{integer}`
20+
21+
error[E0308]: mismatched types
22+
--> $DIR/type-mismatch.rs:7:33
23+
|
24+
LL | let x: unsafe<'a> &'a i32 = &0;
25+
| ------------------ ^^ expected `unsafe<'a> &i32`, found `&{integer}`
26+
| |
27+
| expected due to this
28+
|
29+
= note: expected unsafe binder `unsafe<'a> &'a i32`
30+
found reference `&{integer}`
31+
32+
error: aborting due to 2 previous errors; 1 warning emitted
33+
34+
For more information about this error, try `rustc --explain E0308`.

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