Rollup merge of #132732 - gavincrawford:as_ptr_attribute, r=Urgau

Use attributes for `dangling_pointers_from_temporaries` lint

Checking for dangling pointers by function name isn't ideal, and leaves out certain pointer-returning methods that don't follow the `as_ptr` naming convention. Using an attribute for this lint cleans things up and allows more thorough coverage of other methods, such as `UnsafeCell::get()`.

compiler/rustc_passes/src/check_attr.rs

@@ -162,6 +162,9 @@ impl<'tcx> CheckAttrVisitor<'tcx> {
                     self.check_rustc_std_internal_symbol(attr, span, target)
                 }
                 [sym::naked, ..] => self.check_naked(hir_id, attr, span, target, attrs),
+                [sym::rustc_as_ptr, ..] => {
+                    self.check_applied_to_fn_or_method(hir_id, attr, span, target)
+                }
                 [sym::rustc_never_returns_null_ptr, ..] => {
                     self.check_applied_to_fn_or_method(hir_id, attr, span, target)
                 }