Rustc beta/nightly appears to ignore unsafe blocks inside closure in some cases #85435
Description
The code below compiles with stable rustc (1.52.1), but fails to compile on beta (1.53) and nightly (1.54):
fn main() {
let val: u8 = 5;
let u8_ptr: *const u8 = &val;
let _closure = || {
unsafe {
// Fails compilation with:
// error[E0133]: dereference of raw pointer is unsafe and
// requires unsafe function or block
let tmp = *u8_ptr;
tmp
// Just dereferencing and returning directly compiles fine:
// *u8_ptr
}
};
}On beta and nightly, there is a compilation error due to a missing unsafe block, even though there clearly is one in the code:
error[E0133]: dereference of raw pointer is unsafe and requires unsafe function or block
--> unsafe_deref_test.rs:9:23
|
9 | let tmp = *u8_ptr;
| ^^^^^^^ dereference of raw pointer
|
= note: raw pointers may be NULL, dangling or unaligned; they can violate aliasing rules and cause data races: all of these are undefined behavior
error: aborting due to previous error
For more information about this error, try `rustc --explain E0133`.
Meta
Compilation error:
rustup run beta rustc --version --verbose:
rustc 1.53.0-beta.2 (4bac69dd2 2021-05-07)
binary: rustc
commit-hash: 4bac69dd25089dd2f803f24de2225d84449b6220
commit-date: 2021-05-07
host: x86_64-apple-darwin
release: 1.53.0-beta.2
LLVM version: 12.0.0
Compilation error:
rustup run nightly rustc --version --verbose:
rustc 1.54.0-nightly (fe72845f7 2021-05-16)
binary: rustc
commit-hash: fe72845f7bb6a77b9e671e6a4f32fe714962cec4
commit-date: 2021-05-16
host: x86_64-apple-darwin
release: 1.54.0-nightly
LLVM version: 12.0.1
Successful compilation:
rustup run stable rustc --version --verbose:
rustc 1.52.1 (9bc8c42bb 2021-05-09)
binary: rustc
commit-hash: 9bc8c42bb2f19e745a63f3445f1ac248fb015e53
commit-date: 2021-05-09
host: x86_64-apple-darwin
release: 1.52.1
LLVM version: 12.0.0