transmuting_null: Add checks for without_provenance and without_provenance_mut (#16336)

changelog: [`transmuting_null`]: now checks for
[`ptr::without_provenance`](https://doc.rust-lang.org/core/ptr/fn.without_provenance.html)
and
[`ptr::without_provenance_mut`](https://doc.rust-lang.org/core/ptr/fn.without_provenance_mut.html)
which create null pointers

clippy_lints/src/transmute/transmuting_null.rs

@@ -42,6 +42,18 @@ pub(super) fn check<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>, arg: &'t
         return true;
     }
 
+    // Catching:
+    // `std::mem::transmute(std::ptr::without_provenance::<i32>(0))`
+    // `std::mem::transmute(std::ptr::without_provenance_mut::<i32>(0))`
+    if let ExprKind::Call(func1, [arg1]) = arg.kind
+        && (func1.basic_res().is_diag_item(cx, sym::ptr_without_provenance)
+            || func1.basic_res().is_diag_item(cx, sym::ptr_without_provenance_mut))
+        && is_integer_const(cx, arg1, 0)
+    {
+        span_lint(cx, TRANSMUTING_NULL, expr.span, LINT_MSG);
+        return true;
+    }
+
     // Catching:
     // `std::mem::transmute({ 0 as *const u64 })` and similar const blocks
     if let ExprKind::Block(block, _) = arg.kind

tests/ui/transmuting_null.rs

@@ -47,9 +47,20 @@ fn transumute_single_expr_blocks() {
     }
 }
 
+fn transmute_pointer_creators() {
+    unsafe {
+        let _: &u64 = std::mem::transmute(std::ptr::without_provenance::<u64>(0));
+        //~^ transmuting_null
+
+        let _: &u64 = std::mem::transmute(std::ptr::without_provenance_mut::<u64>(0));
+        //~^ transmuting_null
+    }
+}
+
 fn main() {
     one_liners();
     transmute_const();
     transmute_const_int();
     transumute_single_expr_blocks();
+    transmute_pointer_creators();
 }

tests/ui/transmuting_null.stderr

@@ -37,5 +37,17 @@ error: transmuting a known null pointer into a reference
 LL |         let _: &u64 = std::mem::transmute(const { u64::MIN as *const u64 });
    |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 6 previous errors
+error: transmuting a known null pointer into a reference
+  --> tests/ui/transmuting_null.rs:52:23
+   |
+LL |         let _: &u64 = std::mem::transmute(std::ptr::without_provenance::<u64>(0));
+   |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: transmuting a known null pointer into a reference
+  --> tests/ui/transmuting_null.rs:55:23
+   |
+LL |         let _: &u64 = std::mem::transmute(std::ptr::without_provenance_mut::<u64>(0));
+   |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 8 previous errors