implicit_unsafe_autorefs: lint field access too

compiler/rustc_lint/src/implicit_unsafe_autorefs.rs

@@ -58,8 +58,8 @@ impl<'tcx> LateLintPass<'tcx> for ImplicitUnsafeAutorefs {
  && let [adjustment] = &**adjustments
  // An auto-borrow
  && let Adjust::Borrow(AutoBorrow::Ref(_, mutbl)) = adjustment.kind
- // ... of a deref
- && let ExprKind::Unary(UnOp::Deref, dereferenced) = expr.kind
+ // ... of a place derived from a deref
+ && let ExprKind::Unary(UnOp::Deref, dereferenced) = skip_field_access(&expr.kind)
  // ... of a raw pointer
  && typeck.expr_ty(dereferenced).is_unsafe_ptr()
  {
@@ -81,3 +81,10 @@ impl<'tcx> LateLintPass<'tcx> for ImplicitUnsafeAutorefs {
  }
  }
 }
+
+fn skip_field_access<'a>(mut expr: &'a ExprKind<'a>) -> &'a ExprKind<'a> {
+ while let ExprKind::Field(e, _) = expr {
+ expr = &e.kind;
+ }
+ expr
+}

src/test/ui/lint/implicit_unsafe_autorefs.fixed

@@ -1,15 +1,28 @@
 // check-pass
 // run-rustfix
+#![allow(dead_code)]
 use std::ptr::{addr_of, addr_of_mut};
 
-unsafe fn _test_mut(ptr: *mut [u8]) -> *mut [u8] {
+unsafe fn test_mut(ptr: *mut [u8]) -> *mut [u8] {
  addr_of_mut!((&mut (*ptr))[..16])
  //~^ warn: implicit auto-ref creates a reference to a dereference of a raw pointer
 }
 
-unsafe fn _test_const(ptr: *const [u8]) -> *const [u8] {
+unsafe fn test_const(ptr: *const [u8]) -> *const [u8] {
  addr_of!((&(*ptr))[..16])
  //~^ warn: implicit auto-ref creates a reference to a dereference of a raw pointer
 }
 
+struct Test {
+ field: [u8],
+}
+
+unsafe fn test_field(ptr: *const Test) -> *const [u8] {
+ let l = (&(*ptr).field).len();
+ //~^ warn: implicit auto-ref creates a reference to a dereference of a raw pointer
+
+ addr_of!((&(*ptr).field)[..l - 1])
+ //~^ warn: implicit auto-ref creates a reference to a dereference of a raw pointer
+}
+
 fn main() {}

src/test/ui/lint/implicit_unsafe_autorefs.rs

@@ -1,15 +1,28 @@
 // check-pass
 // run-rustfix
+#![allow(dead_code)]
 use std::ptr::{addr_of, addr_of_mut};
 
-unsafe fn _test_mut(ptr: *mut [u8]) -> *mut [u8] {
+unsafe fn test_mut(ptr: *mut [u8]) -> *mut [u8] {
  addr_of_mut!((*ptr)[..16])
  //~^ warn: implicit auto-ref creates a reference to a dereference of a raw pointer
 }
 
-unsafe fn _test_const(ptr: *const [u8]) -> *const [u8] {
+unsafe fn test_const(ptr: *const [u8]) -> *const [u8] {
  addr_of!((*ptr)[..16])
  //~^ warn: implicit auto-ref creates a reference to a dereference of a raw pointer
 }
 
+struct Test {
+ field: [u8],
+}
+
+unsafe fn test_field(ptr: *const Test) -> *const [u8] {
+ let l = (*ptr).field.len();
+ //~^ warn: implicit auto-ref creates a reference to a dereference of a raw pointer
+
+ addr_of!((*ptr).field[..l - 1])
+ //~^ warn: implicit auto-ref creates a reference to a dereference of a raw pointer
+}
+
 fn main() {}

src/test/ui/lint/implicit_unsafe_autorefs.stderr

@@ -1,5 +1,5 @@
 warning: implicit auto-ref creates a reference to a dereference of a raw pointer
- --> $DIR/implicit_unsafe_autorefs.rs:6:18
+ --> $DIR/implicit_unsafe_autorefs.rs:7:18
  |
 LL | addr_of_mut!((*ptr)[..16])
  | ^^^^^^
@@ -12,7 +12,7 @@ LL | addr_of_mut!((&mut (*ptr))[..16])
  | +++++ +
 
 warning: implicit auto-ref creates a reference to a dereference of a raw pointer
- --> $DIR/implicit_unsafe_autorefs.rs:11:14
+ --> $DIR/implicit_unsafe_autorefs.rs:12:14
  |
 LL | addr_of!((*ptr)[..16])
  | ^^^^^^
@@ -23,5 +23,29 @@ help: try using a raw pointer method instead; or if this reference is intentiona
 LL | addr_of!((&(*ptr))[..16])
  | ++ +
 
-warning: 2 warnings emitted
+warning: implicit auto-ref creates a reference to a dereference of a raw pointer
+ --> $DIR/implicit_unsafe_autorefs.rs:21:13
+ |
+LL | let l = (*ptr).field.len();
+ | ^^^^^^^^^^^^
+ |
+ = note: creating a reference requires the pointer to be valid and imposes aliasing requirements
+help: try using a raw pointer method instead; or if this reference is intentional, make it explicit
+ |
+LL | let l = (&(*ptr).field).len();
+ | ++ +
+
+warning: implicit auto-ref creates a reference to a dereference of a raw pointer
+ --> $DIR/implicit_unsafe_autorefs.rs:24:14
+ |
+LL | addr_of!((*ptr).field[..l - 1])
+ | ^^^^^^^^^^^^
+ |
+ = note: creating a reference requires the pointer to be valid and imposes aliasing requirements
+help: try using a raw pointer method instead; or if this reference is intentional, make it explicit
+ |
+LL | addr_of!((&(*ptr).field)[..l - 1])
+ | ++ +
+
+warning: 4 warnings emitted