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Ensure copy* intrinsics also perform the static self-init checks #142575

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Jun 21, 2025
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7 changes: 6 additions & 1 deletion compiler/rustc_const_eval/src/interpret/memory.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1412,8 +1412,13 @@ impl<'tcx, M: Machine<'tcx>> InterpCx<'tcx, M> {
let src_alloc = self.get_alloc_raw(src_alloc_id)?;
let src_range = alloc_range(src_offset, size);
assert!(!self.memory.validation_in_progress.get(), "we can't be copying during validation");
// For the overlapping case, it is crucial that we trigger the read hook

// Trigger read hooks.
// For the overlapping case, it is crucial that we trigger the read hooks
// before the write hook -- the aliasing model cares about the order.
if let Ok((alloc_id, ..)) = self.ptr_try_get_alloc_id(src, size.bytes() as i64) {
M::before_alloc_read(self, alloc_id)?;
}
M::before_memory_read(
tcx,
&self.machine,
Expand Down
22 changes: 22 additions & 0 deletions tests/ui/statics/read_before_init.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,22 @@
//! This test checks the one code path that does not go through
//! the regular CTFE memory access (as an optimization). We forgot
//! to duplicate the static item self-initialization check, allowing
//! reading from the uninitialized static memory before it was
//! initialized at the end of the static initializer.
//!
//! https://github.com/rust-lang/rust/issues/142532
use std::mem::MaybeUninit;

pub static X: (i32, MaybeUninit<i32>) = (1, foo(&X.0));
//~^ ERROR: encountered static that tried to initialize itself with itself

const fn foo(x: &i32) -> MaybeUninit<i32> {
let mut temp = MaybeUninit::<i32>::uninit();
unsafe {
std::ptr::copy(x, temp.as_mut_ptr(), 1);
}
temp
}

fn main() {}
17 changes: 17 additions & 0 deletions tests/ui/statics/read_before_init.stderr
Original file line number Diff line number Diff line change
@@ -0,0 +1,17 @@
error[E0080]: encountered static that tried to initialize itself with itself
--> $DIR/read_before_init.rs:11:45
|
LL | pub static X: (i32, MaybeUninit<i32>) = (1, foo(&X.0));
| ^^^^^^^^^ evaluation of `X` failed inside this call
|
note: inside `foo`
--> $DIR/read_before_init.rs:17:9
|
LL | std::ptr::copy(x, temp.as_mut_ptr(), 1);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: inside `std::ptr::copy::<i32>`
--> $SRC_DIR/core/src/ptr/mod.rs:LL:COL

error: aborting due to 1 previous error

For more information about this error, try `rustc --explain E0080`.
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