Make sure casts from other types to fat pointers are illegal #25038
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Thanks for the pull request, and welcome! The Rust team is excited to review your changes, and you should hear from @brson (or someone else) soon. If any changes to this PR are deemed necessary, please add them as extra commits. This ensures that the reviewer can see what has changed since they last reviewed the code. The way Github handles out-of-date commits, this should also make it reasonably obvious what issues have or haven't been addressed. Large or tricky changes may require several passes of review and changes. Please see CONTRIBUTING.md for more information. |
bluss
changed the title
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This change catches more invalid casts than I intended.. |
bluss
changed the title
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r? @pnkfelix |
| @@ -14,6 +14,6 @@ fn main() { | |||
| let foo: *mut libc::c_void; | |||
| let cb: &mut Fn() = unsafe { | |||
| &mut *(foo as *mut Fn()) | |||
| //~^ ERROR use of possibly uninitialized variable: `foo` | |||
| //~^ ERROR illegal cast | |||
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Looks like this test case was actually testing the wrong thing. The associated issue is actually just another instance of casting thin <-> fat pointers, and this test case should not have closed that issue. Note that the error is complaining about something completely unrelated to why the code is actually invalid.
It would be great if you could actually fix up this test case to avoid the other reasons why this case is invalid. A corrected test case looks like
fn main() {
let ptr: *mut () = 0 as *mut _;
let _: &mut Fn() = unsafe {
&mut *(ptr as *mut Fn())
};
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absolutely. Finding this test case was a bit confusing. Thanks for the test code.
Fixes ICEs where non-fat pointers and scalars are cast to fat pointers, Fixes rust-lang#21397 Fixes rust-lang#22955 Fixes rust-lang#23237 Fixes rust-lang#24100
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Updated the list of issues this should fix (basically lots of the same kinds of fat pointer casts) |
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Nice. Thank you! |
typeck: Make sure casts from other types to fat pointers are illegal
Fixes ICEs where non-fat pointers and scalars are cast to fat pointers,
Fixes #21397
Fixes #22955
Fixes #23237
Fixes #24100