diff options
| -rw-r--r-- | compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs | 22 | ||||
| -rw-r--r-- | tests/ui/coercion/coerce-block-tail.stderr | 7 | ||||
| -rw-r--r-- | tests/ui/coercion/coerce-box-new-to-unboxed.rs | 4 | ||||
| -rw-r--r-- | tests/ui/coercion/coerce-box-new-to-unboxed.stderr | 19 |
4 files changed, 49 insertions, 3 deletions
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs index 1998a1884b7..a5c6a7f34ef 100644 --- a/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs +++ b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs @@ -3021,6 +3021,28 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { ) { let deref_kind = if checked_ty.is_box() { + // detect Box::new(..) + if let ExprKind::Call(box_new, [_]) = expr.kind + && let ExprKind::Path(qpath) = &box_new.kind + && let Res::Def(DefKind::AssocFn, fn_id) = + self.typeck_results.borrow().qpath_res(qpath, box_new.hir_id) + && let Some(impl_id) = self.tcx.inherent_impl_of_assoc(fn_id) + && self.tcx.type_of(impl_id).skip_binder().is_box() + && self.tcx.item_name(fn_id) == sym::new + { + let l_paren = self.tcx.sess.source_map().next_point(box_new.span); + let r_paren = self.tcx.sess.source_map().end_point(expr.span); + return Some(( + vec![ + (box_new.span.to(l_paren), String::new()), + (r_paren, String::new()), + ], + "consider removing the Box".to_string(), + Applicability::MachineApplicable, + false, + false, + )); + } "unboxing the value" } else if checked_ty.is_ref() { "dereferencing the borrow" diff --git a/tests/ui/coercion/coerce-block-tail.stderr b/tests/ui/coercion/coerce-block-tail.stderr index 1301f3b7813..b358401b706 100644 --- a/tests/ui/coercion/coerce-block-tail.stderr +++ b/tests/ui/coercion/coerce-block-tail.stderr @@ -6,10 +6,11 @@ LL | let _: &i32 = & { Box::new(1i32) }; | = note: expected type `i32` found struct `Box<i32>` -help: consider unboxing the value +help: consider removing the Box + | +LL - let _: &i32 = & { Box::new(1i32) }; +LL + let _: &i32 = & { 1i32 }; | -LL | let _: &i32 = & { *Box::new(1i32) }; - | + error: aborting due to 1 previous error diff --git a/tests/ui/coercion/coerce-box-new-to-unboxed.rs b/tests/ui/coercion/coerce-box-new-to-unboxed.rs new file mode 100644 index 00000000000..63ff0fc4e23 --- /dev/null +++ b/tests/ui/coercion/coerce-box-new-to-unboxed.rs @@ -0,0 +1,4 @@ +fn main() { + let _: String = Box::new(String::new()); + //~^ ERROR mismatched types +} diff --git a/tests/ui/coercion/coerce-box-new-to-unboxed.stderr b/tests/ui/coercion/coerce-box-new-to-unboxed.stderr new file mode 100644 index 00000000000..bdd962686e4 --- /dev/null +++ b/tests/ui/coercion/coerce-box-new-to-unboxed.stderr @@ -0,0 +1,19 @@ +error[E0308]: mismatched types + --> $DIR/coerce-box-new-to-unboxed.rs:2:21 + | +LL | let _: String = Box::new(String::new()); + | ------ ^^^^^^^^^^^^^^^^^^^^^^^ expected `String`, found `Box<String>` + | | + | expected due to this + | + = note: expected struct `String` + found struct `Box<String>` +help: consider removing the Box + | +LL - let _: String = Box::new(String::new()); +LL + let _: String = String::new(); + | + +error: aborting due to 1 previous error + +For more information about this error, try `rustc --explain E0308`. |