Auto merge of #13452 - ljgermain:master, r=Centri3

`invalid_null_ptr_usage`: fix false positives for `std::ptr::slice_from_raw_parts` functions

fixes #13445
changelog: [`invalid_null_ptr_usage`]: fix false positives for `std::ptr::slice_from_raw_parts` functions

clippy_lints/src/ptr.rs

@@ -271,14 +271,18 @@ fn check_invalid_ptr_usage<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
         && let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id()
         && let Some(name) = cx.tcx.get_diagnostic_name(fun_def_id)
     {
+        // TODO: `ptr_slice_from_raw_parts` and its mutable variant should probably still be linted
+        // conditionally based on how the return value is used, but not universally like the other
+        // functions since there are valid uses for null slice pointers.
+        //
+        // See: https://github.com/rust-lang/rust-clippy/pull/13452/files#r1773772034
+
         // `arg` positions where null would cause U.B.
         let arg_indices: &[_] = match name {
             sym::ptr_read
             | sym::ptr_read_unaligned
             | sym::ptr_read_volatile
             | sym::ptr_replace
-            | sym::ptr_slice_from_raw_parts
-            | sym::ptr_slice_from_raw_parts_mut
             | sym::ptr_write
             | sym::ptr_write_bytes
             | sym::ptr_write_unaligned

tests/ui/invalid_null_ptr_usage.fixed

@@ -24,11 +24,8 @@ fn main() {
         let _a: A = std::ptr::read_volatile(core::ptr::NonNull::dangling().as_ptr());
 
         let _a: A = std::ptr::replace(core::ptr::NonNull::dangling().as_ptr(), A);
-
+        let _slice: *const [usize] = std::ptr::slice_from_raw_parts(std::ptr::null_mut(), 0); // shouldn't lint
-        let _slice: *const [usize] = std::ptr::slice_from_raw_parts(core::ptr::NonNull::dangling().as_ptr(), 0);
+        let _slice: *const [usize] = std::ptr::slice_from_raw_parts_mut(std::ptr::null_mut(), 0);
-        let _slice: *const [usize] = std::ptr::slice_from_raw_parts(core::ptr::NonNull::dangling().as_ptr(), 0);
-
-        let _slice: *const [usize] = std::ptr::slice_from_raw_parts_mut(core::ptr::NonNull::dangling().as_ptr(), 0);
 
         std::ptr::swap::<A>(core::ptr::NonNull::dangling().as_ptr(), &mut A);
         std::ptr::swap::<A>(&mut A, core::ptr::NonNull::dangling().as_ptr());

tests/ui/invalid_null_ptr_usage.rs

@@ -24,10 +24,7 @@ fn main() {
         let _a: A = std::ptr::read_volatile(std::ptr::null_mut());
 
         let _a: A = std::ptr::replace(std::ptr::null_mut(), A);
-
+        let _slice: *const [usize] = std::ptr::slice_from_raw_parts(std::ptr::null_mut(), 0); // shouldn't lint
-        let _slice: *const [usize] = std::ptr::slice_from_raw_parts(std::ptr::null(), 0);
-        let _slice: *const [usize] = std::ptr::slice_from_raw_parts(std::ptr::null_mut(), 0);
-
         let _slice: *const [usize] = std::ptr::slice_from_raw_parts_mut(std::ptr::null_mut(), 0);
 
         std::ptr::swap::<A>(std::ptr::null_mut(), &mut A);

tests/ui/invalid_null_ptr_usage.stderr

@@ -85,70 +85,52 @@ LL |         let _a: A = std::ptr::replace(std::ptr::null_mut(), A);
    |                                       ^^^^^^^^^^^^^^^^^^^^ help: change this to: `core::ptr::NonNull::dangling().as_ptr()`
 
 error: pointer must be non-null
-  --> tests/ui/invalid_null_ptr_usage.rs:28:69
+  --> tests/ui/invalid_null_ptr_usage.rs:30:29
-   |
-LL |         let _slice: *const [usize] = std::ptr::slice_from_raw_parts(std::ptr::null(), 0);
-   |                                                                     ^^^^^^^^^^^^^^^^ help: change this to: `core::ptr::NonNull::dangling().as_ptr()`
-
-error: pointer must be non-null
-  --> tests/ui/invalid_null_ptr_usage.rs:29:69
-   |
-LL |         let _slice: *const [usize] = std::ptr::slice_from_raw_parts(std::ptr::null_mut(), 0);
-   |                                                                     ^^^^^^^^^^^^^^^^^^^^ help: change this to: `core::ptr::NonNull::dangling().as_ptr()`
-
-error: pointer must be non-null
-  --> tests/ui/invalid_null_ptr_usage.rs:31:73
-   |
-LL |         let _slice: *const [usize] = std::ptr::slice_from_raw_parts_mut(std::ptr::null_mut(), 0);
-   |                                                                         ^^^^^^^^^^^^^^^^^^^^ help: change this to: `core::ptr::NonNull::dangling().as_ptr()`
-
-error: pointer must be non-null
-  --> tests/ui/invalid_null_ptr_usage.rs:33:29
    |
 LL |         std::ptr::swap::<A>(std::ptr::null_mut(), &mut A);
    |                             ^^^^^^^^^^^^^^^^^^^^ help: change this to: `core::ptr::NonNull::dangling().as_ptr()`
 
 error: pointer must be non-null
-  --> tests/ui/invalid_null_ptr_usage.rs:34:37
+  --> tests/ui/invalid_null_ptr_usage.rs:31:37
    |
 LL |         std::ptr::swap::<A>(&mut A, std::ptr::null_mut());
    |                                     ^^^^^^^^^^^^^^^^^^^^ help: change this to: `core::ptr::NonNull::dangling().as_ptr()`
 
 error: pointer must be non-null
-  --> tests/ui/invalid_null_ptr_usage.rs:36:44
+  --> tests/ui/invalid_null_ptr_usage.rs:33:44
    |
 LL |         std::ptr::swap_nonoverlapping::<A>(std::ptr::null_mut(), &mut A, 0);
    |                                            ^^^^^^^^^^^^^^^^^^^^ help: change this to: `core::ptr::NonNull::dangling().as_ptr()`
 
 error: pointer must be non-null
-  --> tests/ui/invalid_null_ptr_usage.rs:37:52
+  --> tests/ui/invalid_null_ptr_usage.rs:34:52
    |
 LL |         std::ptr::swap_nonoverlapping::<A>(&mut A, std::ptr::null_mut(), 0);
    |                                                    ^^^^^^^^^^^^^^^^^^^^ help: change this to: `core::ptr::NonNull::dangling().as_ptr()`
 
 error: pointer must be non-null
-  --> tests/ui/invalid_null_ptr_usage.rs:39:25
+  --> tests/ui/invalid_null_ptr_usage.rs:36:25
    |
 LL |         std::ptr::write(std::ptr::null_mut(), A);
    |                         ^^^^^^^^^^^^^^^^^^^^ help: change this to: `core::ptr::NonNull::dangling().as_ptr()`
 
 error: pointer must be non-null
-  --> tests/ui/invalid_null_ptr_usage.rs:41:35
+  --> tests/ui/invalid_null_ptr_usage.rs:38:35
    |
 LL |         std::ptr::write_unaligned(std::ptr::null_mut(), A);
    |                                   ^^^^^^^^^^^^^^^^^^^^ help: change this to: `core::ptr::NonNull::dangling().as_ptr()`
 
 error: pointer must be non-null
-  --> tests/ui/invalid_null_ptr_usage.rs:43:34
+  --> tests/ui/invalid_null_ptr_usage.rs:40:34
    |
 LL |         std::ptr::write_volatile(std::ptr::null_mut(), A);
    |                                  ^^^^^^^^^^^^^^^^^^^^ help: change this to: `core::ptr::NonNull::dangling().as_ptr()`
 
 error: pointer must be non-null
-  --> tests/ui/invalid_null_ptr_usage.rs:45:40
+  --> tests/ui/invalid_null_ptr_usage.rs:42:40
    |
 LL |         std::ptr::write_bytes::<usize>(std::ptr::null_mut(), 42, 0);
    |                                        ^^^^^^^^^^^^^^^^^^^^ help: change this to: `core::ptr::NonNull::dangling().as_ptr()`
 
-error: aborting due to 25 previous errors
+error: aborting due to 22 previous errors