implicit_unsafe_autorefs: support overloaded deref

Author: WaffleLapkin

compiler/rustc_lint/src/implicit_unsafe_autorefs.rs

@@ -1,9 +1,9 @@
 use crate::{LateContext, LateLintPass, LintContext};
 
 use rustc_errors::Applicability;
-use rustc_hir::{self as hir, Expr, ExprKind, UnOp};
+use rustc_hir::{Expr, ExprKind, Mutability, UnOp};
 use rustc_middle::ty::{
-    adjustment::{Adjust, AutoBorrow},
+    adjustment::{Adjust, Adjustment, AutoBorrow, OverloadedDeref},
     TyCtxt, TypeckResults,
 };
 
@@ -63,13 +63,13 @@ impl<'tcx> LateLintPass<'tcx> for ImplicitUnsafeAutorefs {
         if let Some(adjustments) = adjustments_table.get(expr.hir_id)
         && let [adjustment] = &**adjustments
         // An auto-borrow
-        && let Adjust::Borrow(AutoBorrow::Ref(_, mutbl)) = adjustment.kind
+        && let Some(mutbl) = has_implicit_borrow(adjustment)
         // ... of a place derived from a deref
         && let ExprKind::Unary(UnOp::Deref, dereferenced) = peel_place_mappers(cx.tcx, typeck, &expr).kind
         // ... of a raw pointer
         && typeck.expr_ty(dereferenced).is_unsafe_ptr()
         {
-            let mutbl = hir::Mutability::prefix_str(&mutbl.into());
+            let mutbl = Mutability::prefix_str(&mutbl.into());
 
             let msg = "implicit auto-ref creates a reference to a dereference of a raw pointer";
             cx.struct_span_lint(IMPLICIT_UNSAFE_AUTOREFS, expr.span, msg, |lint| {
@@ -109,3 +109,12 @@ fn peel_place_mappers<'tcx>(
         }
     }
 }
+
+/// Returns `Some(mutability)` if the argument adjustment has implicit borrow in it.
+fn has_implicit_borrow(Adjustment { kind, .. }: &Adjustment<'_>) -> Option<Mutability> {
+    match kind {
+        &Adjust::Deref(Some(OverloadedDeref { mutbl, .. })) => Some(mutbl),
+        &Adjust::Borrow(AutoBorrow::Ref(_, mutbl)) => Some(mutbl.into()),
+        _ => None,
+    }
+}

src/test/ui/lint/implicit_unsafe_autorefs.fixed

@@ -1,6 +1,7 @@
 // check-pass
 // run-rustfix
 #![allow(dead_code)]
+use std::mem::ManuallyDrop;
 use std::ptr::{addr_of, addr_of_mut};
 
 unsafe fn test_mut(ptr: *mut [u8]) -> *mut [u8] {
@@ -35,4 +36,14 @@ unsafe fn test_builtin_index(a: *mut [String]) {
     //~^ warn: implicit auto-ref creates a reference to a dereference of a raw pointer
 }
 
+unsafe fn test_overloaded_deref_const(ptr: *const ManuallyDrop<Test>) {
+    _ = addr_of!((&(*ptr)).field);
+    //~^ warn: implicit auto-ref creates a reference to a dereference of a raw pointer
+}
+
+unsafe fn test_overloaded_deref_mut(ptr: *mut ManuallyDrop<Test>) {
+    _ = addr_of_mut!((&mut (*ptr)).field);
+    //~^ warn: implicit auto-ref creates a reference to a dereference of a raw pointer
+}
+
 fn main() {}

src/test/ui/lint/implicit_unsafe_autorefs.rs

@@ -1,6 +1,7 @@
 // check-pass
 // run-rustfix
 #![allow(dead_code)]
+use std::mem::ManuallyDrop;
 use std::ptr::{addr_of, addr_of_mut};
 
 unsafe fn test_mut(ptr: *mut [u8]) -> *mut [u8] {
@@ -35,4 +36,14 @@ unsafe fn test_builtin_index(a: *mut [String]) {
     //~^ warn: implicit auto-ref creates a reference to a dereference of a raw pointer
 }
 
+unsafe fn test_overloaded_deref_const(ptr: *const ManuallyDrop<Test>) {
+    _ = addr_of!((*ptr).field);
+    //~^ warn: implicit auto-ref creates a reference to a dereference of a raw pointer
+}
+
+unsafe fn test_overloaded_deref_mut(ptr: *mut ManuallyDrop<Test>) {
+    _ = addr_of_mut!((*ptr).field);
+    //~^ 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:7:18
+  --> $DIR/implicit_unsafe_autorefs.rs:8:18
    |
 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:12:14
+  --> $DIR/implicit_unsafe_autorefs.rs:13:14
    |
 LL |     addr_of!((*ptr)[..16])
    |              ^^^^^^
@@ -24,7 +24,7 @@ LL |     addr_of!((&(*ptr))[..16])
    |              ++      +
 
 warning: implicit auto-ref creates a reference to a dereference of a raw pointer
-  --> $DIR/implicit_unsafe_autorefs.rs:21:13
+  --> $DIR/implicit_unsafe_autorefs.rs:22:13
    |
 LL |     let l = (*ptr).field.len();
    |             ^^^^^^^^^^^^
@@ -36,7 +36,7 @@ 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
+  --> $DIR/implicit_unsafe_autorefs.rs:25:14
    |
 LL |     addr_of!((*ptr).field[..l - 1])
    |              ^^^^^^^^^^^^
@@ -48,7 +48,7 @@ LL |     addr_of!((&(*ptr).field)[..l - 1])
    |              ++            +
 
 warning: implicit auto-ref creates a reference to a dereference of a raw pointer
-  --> $DIR/implicit_unsafe_autorefs.rs:30:9
+  --> $DIR/implicit_unsafe_autorefs.rs:31:9
    |
 LL |     _ = (*a)[0].len();
    |         ^^^^^^^
@@ -60,7 +60,7 @@ LL |     _ = (&(*a)[0]).len();
    |         ++       +
 
 warning: implicit auto-ref creates a reference to a dereference of a raw pointer
-  --> $DIR/implicit_unsafe_autorefs.rs:34:9
+  --> $DIR/implicit_unsafe_autorefs.rs:35:9
    |
 LL |     _ = (*a)[..1][0].len();
    |         ^^^^
@@ -71,5 +71,29 @@ help: try using a raw pointer method instead; or if this reference is intentiona
 LL |     _ = (&(*a))[..1][0].len();
    |         ++    +
 
-warning: 6 warnings emitted
+warning: implicit auto-ref creates a reference to a dereference of a raw pointer
+  --> $DIR/implicit_unsafe_autorefs.rs:40:18
+   |
+LL |     _ = addr_of!((*ptr).field);
+   |                  ^^^^^^
+   |
+   = 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);
+   |                  ++      +
+
+warning: implicit auto-ref creates a reference to a dereference of a raw pointer
+  --> $DIR/implicit_unsafe_autorefs.rs:45:22
+   |
+LL |     _ = addr_of_mut!((*ptr).field);
+   |                      ^^^^^^
+   |
+   = 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_mut!((&mut (*ptr)).field);
+   |                      +++++       +
+
+warning: 8 warnings emitted