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Ensure inherited reference is never set to &mut behind an &

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This commit is contained in:
Jules Bertholet 2024-04-06 17:07:09 -04:00
parent b6c409723b
commit e3945bd3a8
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GPG Key ID: 32034DAFC38C1BFC
6 changed files with 124 additions and 67 deletions
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8
compiler/rustc_ast/src/ast.rs
View File

@ -36,6 +36,7 @@
use rustc_span::source_map::{respan, Spanned};
use rustc_span::symbol::{kw, sym, Ident, Symbol};
use rustc_span::{ErrorGuaranteed, Span, DUMMY_SP};
use std::cmp;
use std::fmt;
use std::mem;
use thin_vec::{thin_vec, ThinVec};
@ -731,6 +732,13 @@ pub fn prefix_str(self) -> &'static str {
Self::MUT_REF_MUT => "mut ref mut ",
}
}
pub fn cap_ref_mutability(mut self, mutbl: Mutability) -> Self {
if let ByRef::Yes(old_mutbl) = self.0 {
self.0 = ByRef::Yes(cmp::min(old_mutbl, mutbl));
}
self
}
}
#[derive(Clone, Encodable, Decodable, Debug)]

91
compiler/rustc_hir_typeck/src/pat.rs
View File

@ -79,6 +79,7 @@ struct TopInfo<'tcx> {
#[derive(Copy, Clone)]
struct PatInfo<'tcx, 'a> {
binding_mode: BindingAnnotation,
max_ref_mutbl: Mutability,
top_info: TopInfo<'tcx>,
decl_origin: Option<DeclOrigin<'a>>,
@ -160,8 +161,13 @@ pub(crate) fn check_pat_top(
decl_origin: Option<DeclOrigin<'tcx>>,
) {
let info = TopInfo { expected, origin_expr, span };
let pat_info =
PatInfo { binding_mode: INITIAL_BM, top_info: info, decl_origin, current_depth: 0 };
let pat_info = PatInfo {
binding_mode: INITIAL_BM,
max_ref_mutbl: Mutability::Mut,
top_info: info,
decl_origin,
current_depth: 0,
};
self.check_pat(pat, expected, pat_info);
}
@ -172,7 +178,8 @@ pub(crate) fn check_pat_top(
/// Conversely, inside this module, `check_pat_top` should never be used.
#[instrument(level = "debug", skip(self, pat_info))]
fn check_pat(&self, pat: &'tcx Pat<'tcx>, expected: Ty<'tcx>, pat_info: PatInfo<'tcx, '_>) {
let PatInfo { binding_mode: def_bm, top_info: ti, current_depth, .. } = pat_info;
let PatInfo { binding_mode: def_bm, max_ref_mutbl, top_info: ti, current_depth, .. } =
pat_info;
let path_res = match &pat.kind {
PatKind::Path(qpath) => Some(
@ -181,10 +188,11 @@ fn check_pat(&self, pat: &'tcx Pat<'tcx>, expected: Ty<'tcx>, pat_info: PatInfo<
_ => None,
};
let adjust_mode = self.calc_adjust_mode(pat, path_res.map(|(res, ..)| res));
let (expected, def_bm, ref_pattern_already_consumed) =
self.calc_default_binding_mode(pat, expected, def_bm, adjust_mode);
let (expected, def_bm, max_ref_mutbl, ref_pattern_already_consumed) =
self.calc_default_binding_mode(pat, expected, def_bm, adjust_mode, max_ref_mutbl);
let pat_info = PatInfo {
binding_mode: def_bm,
max_ref_mutbl,
top_info: ti,
decl_origin: pat_info.decl_origin,
current_depth: current_depth + 1,
@ -289,35 +297,43 @@ fn calc_default_binding_mode(
expected: Ty<'tcx>,
def_bm: BindingAnnotation,
adjust_mode: AdjustMode,
) -> (Ty<'tcx>, BindingAnnotation, bool) {
max_ref_mutbl: Mutability,
) -> (Ty<'tcx>, BindingAnnotation, Mutability, bool) {
if let ByRef::Yes(mutbl) = def_bm.0 {
debug_assert!(mutbl <= max_ref_mutbl);
}
match adjust_mode {
AdjustMode::Pass => (expected, def_bm, false),
AdjustMode::Reset => (expected, INITIAL_BM, false),
AdjustMode::ResetAndConsumeRef(mutbl) => {
let mutbls_match = def_bm.0 == ByRef::Yes(mutbl);
AdjustMode::Pass => (expected, def_bm, max_ref_mutbl, false),
AdjustMode::Reset => (expected, INITIAL_BM, Mutability::Mut, false),
AdjustMode::ResetAndConsumeRef(ref_pat_mutbl) => {
let mutbls_match = def_bm.0 == ByRef::Yes(ref_pat_mutbl);
if pat.span.at_least_rust_2024() && self.tcx.features().ref_pat_eat_one_layer_2024 {
let max_ref_mutbl = cmp::min(max_ref_mutbl, ref_pat_mutbl);
if mutbls_match {
(expected, INITIAL_BM, true)
debug!("consuming inherited reference");
(expected, INITIAL_BM, max_ref_mutbl, true)
} else {
let (new_ty, new_bm) = if mutbl == Mutability::Mut {
self.peel_off_references(pat, expected, def_bm, Mutability::Not)
let (new_ty, new_bm, max_ref_mutbl) = if ref_pat_mutbl == Mutability::Mut {
self.peel_off_references(
pat,
expected,
def_bm,
Mutability::Not,
max_ref_mutbl,
)
} else {
let new_byref = if def_bm.0 == ByRef::Yes(Mutability::Mut) {
ByRef::Yes(Mutability::Not)
} else {
def_bm.0
};
(expected, BindingAnnotation(new_byref, def_bm.1))
(expected, def_bm.cap_ref_mutability(Mutability::Not), Mutability::Not)
};
(new_ty, new_bm, false)
(new_ty, new_bm, max_ref_mutbl, false)
}
} else {
(expected, INITIAL_BM, mutbls_match)
(expected, INITIAL_BM, max_ref_mutbl, mutbls_match)
}
}
AdjustMode::Peel => {
let peeled = self.peel_off_references(pat, expected, def_bm, Mutability::Mut);
(peeled.0, peeled.1, false)
let peeled =
self.peel_off_references(pat, expected, def_bm, Mutability::Mut, max_ref_mutbl);
(peeled.0, peeled.1, peeled.2, false)
}
}
}
@ -398,8 +414,9 @@ fn peel_off_references(
pat: &'tcx Pat<'tcx>,
expected: Ty<'tcx>,
mut def_bm: BindingAnnotation,
max_mutability: Mutability,
) -> (Ty<'tcx>, BindingAnnotation) {
max_peelable_mutability: Mutability,
mut max_ref_mutability: Mutability,
) -> (Ty<'tcx>, BindingAnnotation, Mutability) {
let mut expected = self.try_structurally_resolve_type(pat.span, expected);
// Peel off as many `&` or `&mut` from the scrutinee type as possible. For example,
// for `match &&&mut Some(5)` the loop runs three times, aborting when it reaches
@ -411,7 +428,7 @@ fn peel_off_references(
// See the examples in `ui/match-defbm*.rs`.
let mut pat_adjustments = vec![];
while let ty::Ref(_, inner_ty, inner_mutability) = *expected.kind()
&& inner_mutability <= max_mutability
&& inner_mutability <= max_peelable_mutability
{
debug!("inspecting {:?}", expected);
@ -430,6 +447,11 @@ fn peel_off_references(
// This is because a `& &mut` cannot mutate the underlying value.
ByRef::Yes(Mutability::Not) => Mutability::Not,
});
if pat.span.at_least_rust_2024() && self.tcx.features().ref_pat_eat_one_layer_2024 {
max_ref_mutability = cmp::min(max_ref_mutability, inner_mutability);
def_bm = def_bm.cap_ref_mutability(max_ref_mutability);
}
}
if !pat_adjustments.is_empty() {
@ -440,7 +462,7 @@ fn peel_off_references(
.insert(pat.hir_id, pat_adjustments);
}
(expected, def_bm)
(expected, def_bm, max_ref_mutability)
}
fn check_pat_lit(
@ -1116,15 +1138,10 @@ fn check_pat_tuple_struct(
expected: Ty<'tcx>,
pat_info: PatInfo<'tcx, '_>,
) -> Ty<'tcx> {
let PatInfo { binding_mode: def_bm, top_info: ti, decl_origin, current_depth } = pat_info;
let tcx = self.tcx;
let on_error = |e| {
for pat in subpats {
self.check_pat(
pat,
Ty::new_error(tcx, e),
PatInfo { binding_mode: def_bm, top_info: ti, decl_origin, current_depth },
);
self.check_pat(pat, Ty::new_error(tcx, e), pat_info);
}
};
let report_unexpected_res = |res: Res| {
@ -1169,7 +1186,7 @@ fn check_pat_tuple_struct(
let pat_ty = pat_ty.no_bound_vars().expect("expected fn type");
// Type-check the tuple struct pattern against the expected type.
let diag = self.demand_eqtype_pat_diag(pat.span, expected, pat_ty, ti);
let diag = self.demand_eqtype_pat_diag(pat.span, expected, pat_ty, pat_info.top_info);
let had_err = if let Some(err) = diag {
err.emit();
true
@ -1187,11 +1204,7 @@ fn check_pat_tuple_struct(
for (i, subpat) in subpats.iter().enumerate_and_adjust(variant.fields.len(), ddpos) {
let field = &variant.fields[FieldIdx::from_usize(i)];
let field_ty = self.field_ty(subpat.span, field, args);
self.check_pat(
subpat,
field_ty,
PatInfo { binding_mode: def_bm, top_info: ti, decl_origin, current_depth },
);
self.check_pat(subpat, field_ty, pat_info);
self.tcx.check_stability(
variant.fields[FieldIdx::from_usize(i)].did,

2
compiler/rustc_mir_build/src/thir/pattern/mod.rs
View File

@ -69,7 +69,7 @@ fn lower_pattern(&mut self, pat: &'tcx hir::Pat<'tcx>) -> Box<Pat<'tcx>> {
hir::PatKind::Ref(inner, _)
if self.typeck_results.skipped_ref_pats().contains(pat.hir_id) =>
{
self.lower_pattern_unadjusted(inner)
self.lower_pattern(inner)
}
_ => self.lower_pattern_unadjusted(pat),
};

15
tests/ui/match/ref_pat_eat_one_layer_2024/ref_pat_eat_one_layer_2024.rs
View File

@ -38,6 +38,21 @@ pub fn main() {
if let Some(Some(&mut x)) = &Some(Some(&mut 0)) {
let _: &u32 = x;
}
if let &Some(Some(x)) = &Some(&mut Some(0)) {
let _: &u32 = x;
}
if let Some(&Some(&x)) = &Some(&mut Some(0)) {
let _: u32 = x;
}
if let Some(&Some(&x)) = &Some(&Some(0)) {
let _: u32 = x;
}
if let Some(&Some(&x)) = &Some(&mut Some(0)) {
let _: u32 = x;
}
if let Some(&Some(Some(&x))) = &Some(Some(&mut Some(0))) {
let _: u32 = x;
}
let &mut x = &&mut 0;
let _: &u32 = x;

19
tests/ui/match/ref_pat_eat_one_layer_2024/ref_pat_eat_one_layer_2024_fail.rs
View File

@ -7,22 +7,27 @@ pub fn main() {
if let Some(&mut Some(&_)) = &Some(&Some(0)) {
//~^ ERROR: mismatched types
}
if let Some(&Some(&_)) = &Some(&mut Some(0)) {
if let Some(&Some(&mut _)) = &Some(&mut Some(0)) {
//~^ ERROR: mismatched types
}
if let Some(&Some(x)) = &mut Some(&Some(0)) {
let _: &mut u32 = x;
//~^ ERROR: mismatched types
}
if let Some(&Some(&x)) = Some(&Some(&mut 0)) {
if let Some(&Some(&_)) = Some(&Some(&mut 0)) {
//~^ ERROR: mismatched types
}
if let Some(&Some(&mut _)) = &mut Some(&Some(0)) {
//~^ ERROR: mismatched types
}
if let Some(&Some(Some((&mut _)))) = &Some(Some(&mut Some(0))) {
//~^ ERROR: mismatched types
}
let &mut x = &&0;
//~^ ERROR: mismatched types
let _: &u32 = x;
let &mut x = &&&&&&&&&&&&&&&&&&&&&&&&&&&&0;
let &mut _= &&0;
//~^ ERROR: mismatched types
let &mut _ = &&&&&&&&&&&&&&&&&&&&&&&&&&&&0;
//~^ ERROR: mismatched types
let _: &u32 = x;
}

56
tests/ui/match/ref_pat_eat_one_layer_2024/ref_pat_eat_one_layer_2024_fail.stderr
View File

@ -12,13 +12,13 @@ LL | if let Some(&mut Some(&_)) = &Some(&Some(0)) {
error[E0308]: mismatched types
--> $DIR/ref_pat_eat_one_layer_2024_fail.rs:10:23
|
LL | if let Some(&Some(&_)) = &Some(&mut Some(0)) {
| ^^ ------------------- this expression has type `&Option<&mut Option<{integer}>>`
LL | if let Some(&Some(&mut _)) = &Some(&mut Some(0)) {
| ^^^^^^ ------------------- this expression has type `&Option<&mut Option<{integer}>>`
| |
| expected integer, found `&_`
| expected integer, found `&mut _`
|
= note: expected type `{integer}`
found reference `&_`
= note: expected type `{integer}`
found mutable reference `&mut _`
error[E0308]: mismatched types
--> $DIR/ref_pat_eat_one_layer_2024_fail.rs:14:27
@ -34,42 +34,58 @@ LL | let _: &mut u32 = x;
error[E0308]: mismatched types
--> $DIR/ref_pat_eat_one_layer_2024_fail.rs:17:23
|
LL | if let Some(&Some(&x)) = Some(&Some(&mut 0)) {
LL | if let Some(&Some(&_)) = Some(&Some(&mut 0)) {
| ^^ ------------------- this expression has type `Option<&Option<&mut {integer}>>`
| |
| types differ in mutability
|
= note: expected mutable reference `&mut {integer}`
found reference `&_`
help: consider removing `&` from the pattern
|
LL | if let Some(&Some(x)) = Some(&Some(&mut 0)) {
| ~
error[E0308]: mismatched types
--> $DIR/ref_pat_eat_one_layer_2024_fail.rs:21:9
--> $DIR/ref_pat_eat_one_layer_2024_fail.rs:20:23
|
LL | let &mut x = &&0;
| ^^^^^^ --- this expression has type `&&{integer}`
| |
| expected integer, found `&mut _`
| help: to declare a mutable variable use: `mut x`
LL | if let Some(&Some(&mut _)) = &mut Some(&Some(0)) {
| ^^^^^^ ------------------- this expression has type `&mut Option<&Option<{integer}>>`
| |
| expected integer, found `&mut _`
|
= note: expected type `{integer}`
found mutable reference `&mut _`
error[E0308]: mismatched types
--> $DIR/ref_pat_eat_one_layer_2024_fail.rs:25:9
--> $DIR/ref_pat_eat_one_layer_2024_fail.rs:23:29
|
LL | let &mut x = &&&&&&&&&&&&&&&&&&&&&&&&&&&&0;
LL | if let Some(&Some(Some((&mut _)))) = &Some(Some(&mut Some(0))) {
| ^^^^^^ ------------------------- this expression has type `&Option<Option<&mut Option<{integer}>>>`
| |
| expected integer, found `&mut _`
|
= note: expected type `{integer}`
found mutable reference `&mut _`
error[E0308]: mismatched types
--> $DIR/ref_pat_eat_one_layer_2024_fail.rs:28:9
|
LL | let &mut _= &&0;
| ^^^^^^ --- this expression has type `&&{integer}`
| |
| expected integer, found `&mut _`
|
= note: expected type `{integer}`
found mutable reference `&mut _`
error[E0308]: mismatched types
--> $DIR/ref_pat_eat_one_layer_2024_fail.rs:31:9
|
LL | let &mut _ = &&&&&&&&&&&&&&&&&&&&&&&&&&&&0;
| ^^^^^^ ----------------------------- this expression has type `&&&&&&&&&&&&&&&&&&&&&&&&&&&&{integer}`
| |
| expected integer, found `&mut _`
| help: to declare a mutable variable use: `mut x`
|
= note: expected type `{integer}`
found mutable reference `&mut _`
error: aborting due to 6 previous errors
error: aborting due to 8 previous errors
For more information about this error, try `rustc --explain E0308`.