Update dangling pointer tests

Author: gavincrawford

compiler/rustc_lint/src/dangling.rs

@@ -211,13 +211,14 @@ fn owns_allocation(tcx: TyCtxt<'_>, ty: Ty<'_>) -> bool {
             || inner.ty_adt_def().is_some_and(|def| tcx.is_lang_item(def.did(), LangItem::CStr))
             || owns_allocation(tcx, inner)
     } else if let Some(def) = ty.ty_adt_def() {
-        for lang_item in [LangItem::String, LangItem::MaybeUninit] {
+        for lang_item in [LangItem::String, LangItem::MaybeUninit, LangItem::UnsafeCell] {
             if tcx.is_lang_item(def.did(), lang_item) {
                 return true;
             }
         }
-        tcx.get_diagnostic_name(def.did())
-            .is_some_and(|name| matches!(name, sym::cstring_type | sym::Vec | sym::Cell))
+        tcx.get_diagnostic_name(def.did()).is_some_and(|name| {
+            matches!(name, sym::cstring_type | sym::Vec | sym::Cell | sym::sync_unsafe_cell)
+        })
     } else {
         false
     }

compiler/rustc_span/src/symbol.rs

@@ -1930,6 +1930,7 @@ symbols! {
         surface_async_drop_in_place,
         sym,
         sync,
+        sync_unsafe_cell,
         synthetic,
         t32,
         target,

library/core/src/cell.rs

@@ -2273,6 +2273,7 @@ impl<T: DispatchFromDyn<U>, U> DispatchFromDyn<UnsafeCell<U>> for UnsafeCell<T>
 /// See [`UnsafeCell`] for details.
 #[unstable(feature = "sync_unsafe_cell", issue = "95439")]
 #[repr(transparent)]
+#[rustc_diagnostic_item = "sync_unsafe_cell"]
 #[rustc_pub_transparent]
 pub struct SyncUnsafeCell<T: ?Sized> {
     value: UnsafeCell<T>,

tests/ui/lint/dangling-pointers-from-temporaries/types.rs

@@ -1,6 +1,7 @@
 #![deny(dangling_pointers_from_temporaries)]
+#![feature(sync_unsafe_cell)]
 
-use std::cell::Cell;
+use std::cell::{Cell, SyncUnsafeCell, UnsafeCell};
 use std::ffi::{CStr, CString};
 use std::mem::MaybeUninit;
 
@@ -47,6 +48,10 @@ fn main() {
     //~^ ERROR a dangling pointer will be produced because the temporary `MaybeUninit<u8>` will be dropped
     declval::<Vec<AsPtrFake>>().as_ptr();
     //~^ ERROR a dangling pointer will be produced because the temporary `Vec<AsPtrFake>` will be dropped
+    declval::<UnsafeCell<u8>>().get();
+    //~^ ERROR a dangling pointer will be produced because the temporary `UnsafeCell<u8>` will be dropped
+    declval::<SyncUnsafeCell<u8>>().get();
+    //~^ ERROR a dangling pointer will be produced because the temporary `SyncUnsafeCell<u8>` will be dropped
     declval::<Box<AsPtrFake>>().as_ptr();
     declval::<AsPtrFake>().as_ptr();
 }

tests/ui/lint/dangling-pointers-from-temporaries/types.stderr

@@ -1,5 +1,5 @@
 error: a dangling pointer will be produced because the temporary `CString` will be dropped
-  --> $DIR/types.rs:20:26
+  --> $DIR/types.rs:21:26
    |
 LL |     declval::<CString>().as_ptr();
    |     -------------------- ^^^^^^ this pointer will immediately be invalid
@@ -15,7 +15,7 @@ LL | #![deny(dangling_pointers_from_temporaries)]
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: a dangling pointer will be produced because the temporary `String` will be dropped
-  --> $DIR/types.rs:22:25
+  --> $DIR/types.rs:23:25
    |
 LL |     declval::<String>().as_ptr();
    |     ------------------- ^^^^^^ this pointer will immediately be invalid
@@ -26,7 +26,7 @@ LL |     declval::<String>().as_ptr();
    = help: for more information, see <https://doc.rust-lang.org/reference/destructors.html>
 
 error: a dangling pointer will be produced because the temporary `Vec<u8>` will be dropped
-  --> $DIR/types.rs:24:26
+  --> $DIR/types.rs:25:26
    |
 LL |     declval::<Vec<u8>>().as_ptr();
    |     -------------------- ^^^^^^ this pointer will immediately be invalid
@@ -37,7 +37,7 @@ LL |     declval::<Vec<u8>>().as_ptr();
    = help: for more information, see <https://doc.rust-lang.org/reference/destructors.html>
 
 error: a dangling pointer will be produced because the temporary `Box<CString>` will be dropped
-  --> $DIR/types.rs:26:31
+  --> $DIR/types.rs:27:31
    |
 LL |     declval::<Box<CString>>().as_ptr();
    |     ------------------------- ^^^^^^ this pointer will immediately be invalid
@@ -48,7 +48,7 @@ LL |     declval::<Box<CString>>().as_ptr();
    = help: for more information, see <https://doc.rust-lang.org/reference/destructors.html>
 
 error: a dangling pointer will be produced because the temporary `Box<[u8]>` will be dropped
-  --> $DIR/types.rs:28:28
+  --> $DIR/types.rs:29:28
    |
 LL |     declval::<Box<[u8]>>().as_ptr();
    |     ---------------------- ^^^^^^ this pointer will immediately be invalid
@@ -59,7 +59,7 @@ LL |     declval::<Box<[u8]>>().as_ptr();
    = help: for more information, see <https://doc.rust-lang.org/reference/destructors.html>
 
 error: a dangling pointer will be produced because the temporary `Box<str>` will be dropped
-  --> $DIR/types.rs:30:27
+  --> $DIR/types.rs:31:27
    |
 LL |     declval::<Box<str>>().as_ptr();
    |     --------------------- ^^^^^^ this pointer will immediately be invalid
@@ -70,7 +70,7 @@ LL |     declval::<Box<str>>().as_ptr();
    = help: for more information, see <https://doc.rust-lang.org/reference/destructors.html>
 
 error: a dangling pointer will be produced because the temporary `Box<CStr>` will be dropped
-  --> $DIR/types.rs:32:28
+  --> $DIR/types.rs:33:28
    |
 LL |     declval::<Box<CStr>>().as_ptr();
    |     ---------------------- ^^^^^^ this pointer will immediately be invalid
@@ -81,7 +81,7 @@ LL |     declval::<Box<CStr>>().as_ptr();
    = help: for more information, see <https://doc.rust-lang.org/reference/destructors.html>
 
 error: a dangling pointer will be produced because the temporary `[u8; 10]` will be dropped
-  --> $DIR/types.rs:34:27
+  --> $DIR/types.rs:35:27
    |
 LL |     declval::<[u8; 10]>().as_ptr();
    |     --------------------- ^^^^^^ this pointer will immediately be invalid
@@ -92,7 +92,7 @@ LL |     declval::<[u8; 10]>().as_ptr();
    = help: for more information, see <https://doc.rust-lang.org/reference/destructors.html>
 
 error: a dangling pointer will be produced because the temporary `Box<[u8; 10]>` will be dropped
-  --> $DIR/types.rs:36:32
+  --> $DIR/types.rs:37:32
    |
 LL |     declval::<Box<[u8; 10]>>().as_ptr();
    |     -------------------------- ^^^^^^ this pointer will immediately be invalid
@@ -103,7 +103,7 @@ LL |     declval::<Box<[u8; 10]>>().as_ptr();
    = help: for more information, see <https://doc.rust-lang.org/reference/destructors.html>
 
 error: a dangling pointer will be produced because the temporary `Box<Vec<u8>>` will be dropped
-  --> $DIR/types.rs:38:31
+  --> $DIR/types.rs:39:31
    |
 LL |     declval::<Box<Vec<u8>>>().as_ptr();
    |     ------------------------- ^^^^^^ this pointer will immediately be invalid
@@ -114,7 +114,7 @@ LL |     declval::<Box<Vec<u8>>>().as_ptr();
    = help: for more information, see <https://doc.rust-lang.org/reference/destructors.html>
 
 error: a dangling pointer will be produced because the temporary `Box<String>` will be dropped
-  --> $DIR/types.rs:40:30
+  --> $DIR/types.rs:41:30
    |
 LL |     declval::<Box<String>>().as_ptr();
    |     ------------------------ ^^^^^^ this pointer will immediately be invalid
@@ -125,7 +125,7 @@ LL |     declval::<Box<String>>().as_ptr();
    = help: for more information, see <https://doc.rust-lang.org/reference/destructors.html>
 
 error: a dangling pointer will be produced because the temporary `Box<Box<Box<Box<[u8]>>>>` will be dropped
-  --> $DIR/types.rs:42:43
+  --> $DIR/types.rs:43:43
    |
 LL |     declval::<Box<Box<Box<Box<[u8]>>>>>().as_ptr();
    |     ------------------------------------- ^^^^^^ this pointer will immediately be invalid
@@ -136,7 +136,7 @@ LL |     declval::<Box<Box<Box<Box<[u8]>>>>>().as_ptr();
    = help: for more information, see <https://doc.rust-lang.org/reference/destructors.html>
 
 error: a dangling pointer will be produced because the temporary `Cell<u8>` will be dropped
-  --> $DIR/types.rs:44:27
+  --> $DIR/types.rs:45:27
    |
 LL |     declval::<Cell<u8>>().as_ptr();
    |     --------------------- ^^^^^^ this pointer will immediately be invalid
@@ -147,7 +147,7 @@ LL |     declval::<Cell<u8>>().as_ptr();
    = help: for more information, see <https://doc.rust-lang.org/reference/destructors.html>
 
 error: a dangling pointer will be produced because the temporary `MaybeUninit<u8>` will be dropped
-  --> $DIR/types.rs:46:34
+  --> $DIR/types.rs:47:34
    |
 LL |     declval::<MaybeUninit<u8>>().as_ptr();
    |     ---------------------------- ^^^^^^ this pointer will immediately be invalid
@@ -158,7 +158,7 @@ LL |     declval::<MaybeUninit<u8>>().as_ptr();
    = help: for more information, see <https://doc.rust-lang.org/reference/destructors.html>
 
 error: a dangling pointer will be produced because the temporary `Vec<AsPtrFake>` will be dropped
-  --> $DIR/types.rs:48:33
+  --> $DIR/types.rs:49:33
    |
 LL |     declval::<Vec<AsPtrFake>>().as_ptr();
    |     --------------------------- ^^^^^^ this pointer will immediately be invalid
@@ -168,5 +168,27 @@ LL |     declval::<Vec<AsPtrFake>>().as_ptr();
    = note: pointers do not have a lifetime; when calling `as_ptr` the `Vec<AsPtrFake>` will be deallocated at the end of the statement because nothing is referencing it as far as the type system is concerned
    = help: for more information, see <https://doc.rust-lang.org/reference/destructors.html>
 
-error: aborting due to 15 previous errors
+error: a dangling pointer will be produced because the temporary `UnsafeCell<u8>` will be dropped
+  --> $DIR/types.rs:51:33
+   |
+LL |     declval::<UnsafeCell<u8>>().get();
+   |     --------------------------- ^^^ this pointer will immediately be invalid
+   |     |
+   |     this `UnsafeCell<u8>` is deallocated at the end of the statement, bind it to a variable to extend its lifetime
+   |
+   = note: pointers do not have a lifetime; when calling `get` the `UnsafeCell<u8>` will be deallocated at the end of the statement because nothing is referencing it as far as the type system is concerned
+   = help: for more information, see <https://doc.rust-lang.org/reference/destructors.html>
+
+error: a dangling pointer will be produced because the temporary `SyncUnsafeCell<u8>` will be dropped
+  --> $DIR/types.rs:53:37
+   |
+LL |     declval::<SyncUnsafeCell<u8>>().get();
+   |     ------------------------------- ^^^ this pointer will immediately be invalid
+   |     |
+   |     this `SyncUnsafeCell<u8>` is deallocated at the end of the statement, bind it to a variable to extend its lifetime
+   |
+   = note: pointers do not have a lifetime; when calling `get` the `SyncUnsafeCell<u8>` will be deallocated at the end of the statement because nothing is referencing it as far as the type system is concerned
+   = help: for more information, see <https://doc.rust-lang.org/reference/destructors.html>
+
+error: aborting due to 17 previous errors