diff --git a/compiler/rustc_passes/src/dead.rs b/compiler/rustc_passes/src/dead.rs index d51b501f7ae3d..62a95aa57c29f 100644 --- a/compiler/rustc_passes/src/dead.rs +++ b/compiler/rustc_passes/src/dead.rs @@ -37,15 +37,6 @@ fn should_explore(tcx: TyCtxt<'_>, hir_id: hir::HirId) -> bool { ) } -fn base_expr<'a>(mut expr: &'a hir::Expr<'a>) -> &'a hir::Expr<'a> { - loop { - match expr.kind { - hir::ExprKind::Field(base, ..) => expr = base, - _ => return expr, - } - } -} - struct MarkSymbolVisitor<'tcx> { worklist: Vec, tcx: TyCtxt<'tcx>, @@ -143,6 +134,22 @@ impl<'tcx> MarkSymbolVisitor<'tcx> { } } + fn handle_assign(&mut self, expr: &'tcx hir::Expr<'tcx>) { + if self + .typeck_results() + .expr_adjustments(expr) + .iter() + .any(|adj| matches!(adj.kind, ty::adjustment::Adjust::Deref(_))) + { + self.visit_expr(expr); + } else if let hir::ExprKind::Field(base, ..) = expr.kind { + // Ignore write to field + self.handle_assign(base); + } else { + self.visit_expr(expr); + } + } + fn handle_field_pattern_match( &mut self, lhs: &hir::Pat<'_>, @@ -272,8 +279,7 @@ impl<'tcx> Visitor<'tcx> for MarkSymbolVisitor<'tcx> { self.lookup_and_handle_method(expr.hir_id); } hir::ExprKind::Assign(ref left, ref right, ..) => { - // Ignore write to field - self.visit_expr(base_expr(left)); + self.handle_assign(left); self.visit_expr(right); return; } diff --git a/src/test/ui/lint/dead-code/write-only-field.rs b/src/test/ui/lint/dead-code/write-only-field.rs index 78cfcfda8f971..7b3f1e9f5b6cb 100644 --- a/src/test/ui/lint/dead-code/write-only-field.rs +++ b/src/test/ui/lint/dead-code/write-only-field.rs @@ -17,4 +17,53 @@ fn field_write(s: &mut S) { fn main() { let mut s = S { f: 0, sub: Sub { f: 0 } }; field_write(&mut s); + + auto_deref(); + nested_boxes(); +} + +fn auto_deref() { + struct E { + x: bool, + y: bool, //~ ERROR: field is never read + } + + struct P<'a> { + e: &'a mut E + } + + impl P<'_> { + fn f(&mut self) { + self.e.x = true; + self.e.y = true; + } + } + + let mut e = E { x: false, y: false }; + let mut p = P { e: &mut e }; + p.f(); + assert!(e.x); +} + +fn nested_boxes() { + struct A { + b: Box, + } + + struct B { + c: Box, + } + + struct C { + u: u32, //~ ERROR: field is never read + v: u32, //~ ERROR: field is never read + } + + let mut a = A { + b: Box::new(B { + c: Box::new(C { u: 0, v: 0 }), + }), + }; + a.b.c.v = 10; + a.b.c = Box::new(C { u: 1, v: 2 }); } diff --git a/src/test/ui/lint/dead-code/write-only-field.stderr b/src/test/ui/lint/dead-code/write-only-field.stderr index 70d2149665b20..a191d22c8b94c 100644 --- a/src/test/ui/lint/dead-code/write-only-field.stderr +++ b/src/test/ui/lint/dead-code/write-only-field.stderr @@ -22,5 +22,23 @@ error: field is never read: `f` LL | f: i32, | ^^^^^^ -error: aborting due to 3 previous errors +error: field is never read: `y` + --> $DIR/write-only-field.rs:28:9 + | +LL | y: bool, + | ^^^^^^^ + +error: field is never read: `u` + --> $DIR/write-only-field.rs:58:9 + | +LL | u: u32, + | ^^^^^^ + +error: field is never read: `v` + --> $DIR/write-only-field.rs:59:9 + | +LL | v: u32, + | ^^^^^^ + +error: aborting due to 6 previous errors