diff --git a/compiler/rustc_const_eval/src/transform/check_consts/check.rs b/compiler/rustc_const_eval/src/transform/check_consts/check.rs index ee3f349c6b83c..28dc69859fd77 100644 --- a/compiler/rustc_const_eval/src/transform/check_consts/check.rs +++ b/compiler/rustc_const_eval/src/transform/check_consts/check.rs @@ -449,35 +449,27 @@ impl<'tcx> Visitor<'tcx> for Checker<'_, 'tcx> { } } - Rvalue::Ref(_, BorrowKind::Mut { .. }, place) => { - let ty = place.ty(self.body, self.tcx).ty; - let is_allowed = match ty.kind() { - // Inside a `static mut`, `&mut [...]` is allowed. - ty::Array(..) | ty::Slice(_) - if self.const_kind() == hir::ConstContext::Static(hir::Mutability::Mut) => - { - true - } - - // FIXME(ecstaticmorse): We could allow `&mut []` inside a const context given - // that this is merely a ZST and it is already eligible for promotion. - // This may require an RFC? - /* - ty::Array(_, len) if len.try_eval_target_usize(cx.tcx, cx.param_env) == Some(0) - => true, - */ - _ => false, - }; + Rvalue::Ref(_, BorrowKind::Mut { .. }, place) + | Rvalue::AddressOf(Mutability::Mut, place) => { + // Inside mutable statics, we allow arbitrary mutable references. + // We've allowed `static mut FOO = &mut [elements];` for a long time (the exact + // reasons why are lost to history), and there is no reason to restrict that to + // arrays and slices. + let is_allowed = + self.const_kind() == hir::ConstContext::Static(hir::Mutability::Mut); if !is_allowed { - self.check_mut_borrow(place.local, hir::BorrowKind::Ref) + self.check_mut_borrow( + place.local, + if matches!(rvalue, Rvalue::Ref(..)) { + hir::BorrowKind::Ref + } else { + hir::BorrowKind::Raw + }, + ); } } - Rvalue::AddressOf(Mutability::Mut, place) => { - self.check_mut_borrow(place.local, hir::BorrowKind::Raw) - } - Rvalue::Ref(_, BorrowKind::Shared | BorrowKind::Fake, place) | Rvalue::AddressOf(Mutability::Not, place) => { let borrowed_place_has_mut_interior = qualifs::in_place::( diff --git a/tests/ui/array-slice-vec/check-static-mut-slices.rs b/tests/ui/array-slice-vec/check-static-mut-slices.rs deleted file mode 100644 index b89c634036e31..0000000000000 --- a/tests/ui/array-slice-vec/check-static-mut-slices.rs +++ /dev/null @@ -1,15 +0,0 @@ -// run-pass -#![allow(dead_code)] - -// Checks that mutable static items can have mutable slices - - -static mut TEST: &'static mut [isize] = &mut [1]; -static mut EMPTY: &'static mut [isize] = &mut []; - -pub fn main() { - unsafe { - TEST[0] += 1; - assert_eq!(TEST[0], 2); - } -} diff --git a/tests/ui/consts/const-address-of-mut.rs b/tests/ui/consts/const-address-of-mut.rs index 5f0c76d628555..0018bf18e419b 100644 --- a/tests/ui/consts/const-address-of-mut.rs +++ b/tests/ui/consts/const-address-of-mut.rs @@ -4,8 +4,6 @@ const A: () = { let mut x = 2; &raw mut x; }; //~ mutable pointer static B: () = { let mut x = 2; &raw mut x; }; //~ mutable pointer -static mut C: () = { let mut x = 2; &raw mut x; }; //~ mutable pointer - const fn foo() { let mut x = 0; let y = &raw mut x; //~ mutable pointer diff --git a/tests/ui/consts/const-address-of-mut.stderr b/tests/ui/consts/const-address-of-mut.stderr index 1b371fcee984b..95a91ff463f69 100644 --- a/tests/ui/consts/const-address-of-mut.stderr +++ b/tests/ui/consts/const-address-of-mut.stderr @@ -18,18 +18,8 @@ LL | static B: () = { let mut x = 2; &raw mut x; }; = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date -error[E0658]: raw mutable pointers are not allowed in statics - --> $DIR/const-address-of-mut.rs:7:37 - | -LL | static mut C: () = { let mut x = 2; &raw mut x; }; - | ^^^^^^^^^^ - | - = note: see issue #57349 for more information - = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable - = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date - error[E0658]: raw mutable pointers are not allowed in constant functions - --> $DIR/const-address-of-mut.rs:11:13 + --> $DIR/const-address-of-mut.rs:9:13 | LL | let y = &raw mut x; | ^^^^^^^^^^ @@ -38,6 +28,6 @@ LL | let y = &raw mut x; = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date -error: aborting due to 4 previous errors +error: aborting due to 3 previous errors For more information about this error, try `rustc --explain E0658`. diff --git a/tests/ui/consts/miri_unleashed/mutable_references_err.32bit.stderr b/tests/ui/consts/miri_unleashed/mutable_references_err.32bit.stderr index 2df80020fdc91..4793466a98784 100644 --- a/tests/ui/consts/miri_unleashed/mutable_references_err.32bit.stderr +++ b/tests/ui/consts/miri_unleashed/mutable_references_err.32bit.stderr @@ -133,11 +133,6 @@ help: skipping check for `const_mut_refs` feature | LL | static mut MUT_TO_READONLY: &mut i32 = unsafe { &mut *(&READONLY as *const _ as *mut _) }; | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -help: skipping check that does not even have a feature gate - --> $DIR/mutable_references_err.rs:40:49 - | -LL | static mut MUT_TO_READONLY: &mut i32 = unsafe { &mut *(&READONLY as *const _ as *mut _) }; - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: skipping check that does not even have a feature gate --> $DIR/mutable_references_err.rs:47:44 | @@ -148,11 +143,6 @@ help: skipping check that does not even have a feature gate | LL | const POINTS_TO_MUTABLE1: &i32 = unsafe { &MUTABLE }; | ^^^^^^^ -help: skipping check that does not even have a feature gate - --> $DIR/mutable_references_err.rs:50:36 - | -LL | static mut MUTABLE_REF: &mut i32 = &mut 42; - | ^^^^^^^ help: skipping check that does not even have a feature gate --> $DIR/mutable_references_err.rs:51:45 | diff --git a/tests/ui/consts/miri_unleashed/mutable_references_err.64bit.stderr b/tests/ui/consts/miri_unleashed/mutable_references_err.64bit.stderr index 3ff6811ea61fb..f5f7b605c9416 100644 --- a/tests/ui/consts/miri_unleashed/mutable_references_err.64bit.stderr +++ b/tests/ui/consts/miri_unleashed/mutable_references_err.64bit.stderr @@ -133,11 +133,6 @@ help: skipping check for `const_mut_refs` feature | LL | static mut MUT_TO_READONLY: &mut i32 = unsafe { &mut *(&READONLY as *const _ as *mut _) }; | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ -help: skipping check that does not even have a feature gate - --> $DIR/mutable_references_err.rs:40:49 - | -LL | static mut MUT_TO_READONLY: &mut i32 = unsafe { &mut *(&READONLY as *const _ as *mut _) }; - | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: skipping check that does not even have a feature gate --> $DIR/mutable_references_err.rs:47:44 | @@ -148,11 +143,6 @@ help: skipping check that does not even have a feature gate | LL | const POINTS_TO_MUTABLE1: &i32 = unsafe { &MUTABLE }; | ^^^^^^^ -help: skipping check that does not even have a feature gate - --> $DIR/mutable_references_err.rs:50:36 - | -LL | static mut MUTABLE_REF: &mut i32 = &mut 42; - | ^^^^^^^ help: skipping check that does not even have a feature gate --> $DIR/mutable_references_err.rs:51:45 | diff --git a/tests/ui/consts/static-mut-refs.rs b/tests/ui/consts/static-mut-refs.rs new file mode 100644 index 0000000000000..ff865da5aa861 --- /dev/null +++ b/tests/ui/consts/static-mut-refs.rs @@ -0,0 +1,24 @@ +// run-pass +#![allow(dead_code)] + +// Checks that mutable static items can have mutable slices and other references + + +static mut TEST: &'static mut [isize] = &mut [1]; +static mut EMPTY: &'static mut [isize] = &mut []; +static mut INT: &'static mut isize = &mut 1; + +// And the same for raw pointers. + +static mut TEST_RAW: *mut [isize] = &mut [1isize] as *mut _; +static mut EMPTY_RAW: *mut [isize] = &mut [] as *mut _; +static mut INT_RAW: *mut isize = &mut 1isize as *mut _; + +pub fn main() { + unsafe { + TEST[0] += 1; + assert_eq!(TEST[0], 2); + *INT_RAW += 1; + assert_eq!(*INT_RAW, 2); + } +} diff --git a/tests/ui/consts/static_mut_containing_mut_ref2.rs b/tests/ui/consts/static_mut_containing_mut_ref2.rs index fa79a78eab424..b71f1122cd00c 100644 --- a/tests/ui/consts/static_mut_containing_mut_ref2.rs +++ b/tests/ui/consts/static_mut_containing_mut_ref2.rs @@ -7,7 +7,7 @@ static mut STDERR_BUFFER_SPACE: u8 = 0; pub static mut STDERR_BUFFER: () = unsafe { *(&mut STDERR_BUFFER_SPACE) = 42; //[mut_refs]~^ ERROR could not evaluate static initializer - //[stock]~^^ ERROR mutable references are not allowed in statics + //[stock]~^^ ERROR mutation through a reference is not allowed in statics //[mut_refs]~^^^ WARN mutable reference of mutable static is discouraged [static_mut_ref] //[stock]~^^^^ WARN mutable reference of mutable static is discouraged [static_mut_ref] }; diff --git a/tests/ui/consts/static_mut_containing_mut_ref2.stock.stderr b/tests/ui/consts/static_mut_containing_mut_ref2.stock.stderr index e9fe82d2f87a6..aea5b8a33b54c 100644 --- a/tests/ui/consts/static_mut_containing_mut_ref2.stock.stderr +++ b/tests/ui/consts/static_mut_containing_mut_ref2.stock.stderr @@ -13,11 +13,11 @@ help: mutable references are dangerous since if there's any other pointer or ref LL | *addr_of_mut!(STDERR_BUFFER_SPACE) = 42; | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -error[E0658]: mutable references are not allowed in statics - --> $DIR/static_mut_containing_mut_ref2.rs:8:6 +error[E0658]: mutation through a reference is not allowed in statics + --> $DIR/static_mut_containing_mut_ref2.rs:8:5 | LL | *(&mut STDERR_BUFFER_SPACE) = 42; - | ^^^^^^^^^^^^^^^^^^^^^^^^^^ + | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | = note: see issue #57349 for more information = help: add `#![feature(const_mut_refs)]` to the crate attributes to enable