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static mut: allow reference to arbitrary types, not just slices and arrays
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@ -476,35 +476,27 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> {
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}
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}
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Rvalue::Ref(_, BorrowKind::Mut { .. }, place) => {
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let ty = place.ty(self.body, self.tcx).ty;
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let is_allowed = match ty.kind() {
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// Inside a `static mut`, `&mut [...]` is allowed.
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ty::Array(..) | ty::Slice(_)
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if self.const_kind() == hir::ConstContext::Static(hir::Mutability::Mut) =>
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{
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true
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}
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// FIXME(ecstaticmorse): We could allow `&mut []` inside a const context given
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// that this is merely a ZST and it is already eligible for promotion.
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// This may require an RFC?
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/*
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ty::Array(_, len) if len.try_eval_target_usize(cx.tcx, cx.param_env) == Some(0)
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=> true,
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*/
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_ => false,
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};
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Rvalue::Ref(_, BorrowKind::Mut { .. }, place)
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| Rvalue::AddressOf(Mutability::Mut, place) => {
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// Inside mutable statics, we allow arbitrary mutable references.
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// We've allowed `static mut FOO = &mut [elements];` for a long time (the exact
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// reasons why are lost to history), and there is no reason to restrict that to
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// arrays and slices.
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let is_allowed =
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self.const_kind() == hir::ConstContext::Static(hir::Mutability::Mut);
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if !is_allowed {
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self.check_mut_borrow(place.local, hir::BorrowKind::Ref)
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self.check_mut_borrow(
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place.local,
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if matches!(rvalue, Rvalue::Ref(..)) {
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hir::BorrowKind::Ref
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} else {
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hir::BorrowKind::Raw
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},
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);
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}
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}
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Rvalue::AddressOf(Mutability::Mut, place) => {
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self.check_mut_borrow(place.local, hir::BorrowKind::Raw)
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}
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Rvalue::Ref(_, BorrowKind::Shared | BorrowKind::Fake, place)
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| Rvalue::AddressOf(Mutability::Not, place) => {
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let borrowed_place_has_mut_interior = qualifs::in_place::<HasMutInterior, _>(
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@ -1,15 +0,0 @@
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// run-pass
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#![allow(dead_code)]
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// Checks that mutable static items can have mutable slices
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static mut TEST: &'static mut [isize] = &mut [1];
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static mut EMPTY: &'static mut [isize] = &mut [];
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pub fn main() {
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unsafe {
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TEST[0] += 1;
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assert_eq!(TEST[0], 2);
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}
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}
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@ -4,8 +4,6 @@ const A: () = { let mut x = 2; &raw mut x; }; //~ mutable pointer
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static B: () = { let mut x = 2; &raw mut x; }; //~ mutable pointer
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static mut C: () = { let mut x = 2; &raw mut x; }; //~ mutable pointer
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const fn foo() {
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let mut x = 0;
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let y = &raw mut x; //~ mutable pointer
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@ -18,18 +18,8 @@ LL | static B: () = { let mut x = 2; &raw mut x; };
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= help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
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= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
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error[E0658]: raw mutable pointers are not allowed in statics
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--> $DIR/const-address-of-mut.rs:7:37
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LL | static mut C: () = { let mut x = 2; &raw mut x; };
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| ^^^^^^^^^^
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= note: see issue #57349 <https://github.com/rust-lang/rust/issues/57349> for more information
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= help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
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= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
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error[E0658]: raw mutable pointers are not allowed in constant functions
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--> $DIR/const-address-of-mut.rs:11:13
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--> $DIR/const-address-of-mut.rs:9:13
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LL | let y = &raw mut x;
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| ^^^^^^^^^^
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@ -38,6 +28,6 @@ LL | let y = &raw mut x;
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= help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
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= note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date
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error: aborting due to 4 previous errors
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error: aborting due to 3 previous errors
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For more information about this error, try `rustc --explain E0658`.
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@ -133,11 +133,6 @@ help: skipping check for `const_mut_refs` feature
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LL | static mut MUT_TO_READONLY: &mut i32 = unsafe { &mut *(&READONLY as *const _ as *mut _) };
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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help: skipping check that does not even have a feature gate
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--> $DIR/mutable_references_err.rs:40:49
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LL | static mut MUT_TO_READONLY: &mut i32 = unsafe { &mut *(&READONLY as *const _ as *mut _) };
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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help: skipping check that does not even have a feature gate
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--> $DIR/mutable_references_err.rs:47:44
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@ -148,11 +143,6 @@ help: skipping check that does not even have a feature gate
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LL | const POINTS_TO_MUTABLE1: &i32 = unsafe { &MUTABLE };
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| ^^^^^^^
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help: skipping check that does not even have a feature gate
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--> $DIR/mutable_references_err.rs:50:36
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LL | static mut MUTABLE_REF: &mut i32 = &mut 42;
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| ^^^^^^^
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help: skipping check that does not even have a feature gate
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--> $DIR/mutable_references_err.rs:51:45
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@ -133,11 +133,6 @@ help: skipping check for `const_mut_refs` feature
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LL | static mut MUT_TO_READONLY: &mut i32 = unsafe { &mut *(&READONLY as *const _ as *mut _) };
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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help: skipping check that does not even have a feature gate
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--> $DIR/mutable_references_err.rs:40:49
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LL | static mut MUT_TO_READONLY: &mut i32 = unsafe { &mut *(&READONLY as *const _ as *mut _) };
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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help: skipping check that does not even have a feature gate
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--> $DIR/mutable_references_err.rs:47:44
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@ -148,11 +143,6 @@ help: skipping check that does not even have a feature gate
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LL | const POINTS_TO_MUTABLE1: &i32 = unsafe { &MUTABLE };
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| ^^^^^^^
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help: skipping check that does not even have a feature gate
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--> $DIR/mutable_references_err.rs:50:36
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LL | static mut MUTABLE_REF: &mut i32 = &mut 42;
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| ^^^^^^^
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help: skipping check that does not even have a feature gate
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--> $DIR/mutable_references_err.rs:51:45
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24
tests/ui/consts/static-mut-refs.rs
Normal file
24
tests/ui/consts/static-mut-refs.rs
Normal file
@ -0,0 +1,24 @@
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// run-pass
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#![allow(dead_code)]
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// Checks that mutable static items can have mutable slices and other references
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static mut TEST: &'static mut [isize] = &mut [1];
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static mut EMPTY: &'static mut [isize] = &mut [];
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static mut INT: &'static mut isize = &mut 1;
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// And the same for raw pointers.
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static mut TEST_RAW: *mut [isize] = &mut [1isize] as *mut _;
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static mut EMPTY_RAW: *mut [isize] = &mut [] as *mut _;
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static mut INT_RAW: *mut isize = &mut 1isize as *mut _;
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pub fn main() {
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unsafe {
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TEST[0] += 1;
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assert_eq!(TEST[0], 2);
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*INT_RAW += 1;
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assert_eq!(*INT_RAW, 2);
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}
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}
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@ -7,7 +7,7 @@ static mut STDERR_BUFFER_SPACE: u8 = 0;
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pub static mut STDERR_BUFFER: () = unsafe {
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*(&mut STDERR_BUFFER_SPACE) = 42;
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//[mut_refs]~^ ERROR could not evaluate static initializer
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//[stock]~^^ ERROR mutable references are not allowed in statics
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//[stock]~^^ ERROR mutation through a reference is not allowed in statics
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//[mut_refs]~^^^ WARN mutable reference of mutable static is discouraged [static_mut_ref]
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//[stock]~^^^^ WARN mutable reference of mutable static is discouraged [static_mut_ref]
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};
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@ -13,11 +13,11 @@ help: mutable references are dangerous since if there's any other pointer or ref
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LL | *addr_of_mut!(STDERR_BUFFER_SPACE) = 42;
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| ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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error[E0658]: mutable references are not allowed in statics
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--> $DIR/static_mut_containing_mut_ref2.rs:8:6
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error[E0658]: mutation through a reference is not allowed in statics
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--> $DIR/static_mut_containing_mut_ref2.rs:8:5
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LL | *(&mut STDERR_BUFFER_SPACE) = 42;
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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= note: see issue #57349 <https://github.com/rust-lang/rust/issues/57349> for more information
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= help: add `#![feature(const_mut_refs)]` to the crate attributes to enable
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