3fdd8d5ef3
The implied deref to statics introduced by HIR->THIR lowering is only
used to create place expressions, it lacks unsafe semantics.
It is also confusing, as there is no visible `*ident` in the source.
For both classes of "unsafe static" (extern static and static mut)
allow this operation.
We lack a clear story around `thread_local! { static mut }`, which
is actually its own category of item that reuses the static syntax but
has its own rules. It's possible they should be similarly included, but
in the absence of a good reason one way or another, we do not bless it.
37 lines
826 B
Rust
37 lines
826 B
Rust
//@run-pass
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#![feature(const_mut_refs)]
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#![feature(sync_unsafe_cell)]
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use std::cell::SyncUnsafeCell;
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use std::ptr;
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#[repr(C)]
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struct SyncPtr {
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foo: *mut u32,
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}
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unsafe impl Sync for SyncPtr {}
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static mut STATIC: u32 = 42;
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static INTERIOR_MUTABLE_STATIC: SyncUnsafeCell<u32> = SyncUnsafeCell::new(42);
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// A static that mutably points to STATIC.
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static PTR: SyncPtr = SyncPtr { foo: ptr::addr_of_mut!(STATIC) };
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static INTERIOR_MUTABLE_PTR: SyncPtr =
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SyncPtr { foo: ptr::addr_of!(INTERIOR_MUTABLE_STATIC) as *mut u32 };
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fn main() {
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let ptr = PTR.foo;
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unsafe {
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assert_eq!(*ptr, 42);
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*ptr = 0;
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assert_eq!(*PTR.foo, 0);
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}
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let ptr = INTERIOR_MUTABLE_PTR.foo;
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unsafe {
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assert_eq!(*ptr, 42);
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*ptr = 0;
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assert_eq!(*INTERIOR_MUTABLE_PTR.foo, 0);
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}
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}
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