diff options
3 files changed, 85 insertions, 1 deletions
diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs index ab0f356ce91..6fdf616f50e 100644 --- a/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs +++ b/compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs @@ -948,6 +948,17 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { &mut err, ); + self.suggest_deref_unwrap_or( + &mut err, + error_span, + callee_ty, + call_ident, + expected_ty, + provided_ty, + provided_args[*provided_idx], + is_method, + ); + // Call out where the function is defined self.label_fn_like( &mut err, diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs index 5975c52ca46..15a1a18daa7 100644 --- a/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs +++ b/compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs @@ -1429,6 +1429,71 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { true } + // Suggest to change `Option<&Vec<T>>::unwrap_or(&[])` to `Option::map_or(&[], |v| v)`. + #[instrument(level = "trace", skip(self, err, provided_expr))] + pub(crate) fn suggest_deref_unwrap_or( + &self, + err: &mut Diag<'_>, + error_span: Span, + callee_ty: Option<Ty<'tcx>>, + call_ident: Option<Ident>, + expected_ty: Ty<'tcx>, + provided_ty: Ty<'tcx>, + provided_expr: &Expr<'tcx>, + is_method: bool, + ) { + if !is_method { + return; + } + let Some(callee_ty) = callee_ty else { + return; + }; + let ty::Adt(callee_adt, _) = callee_ty.peel_refs().kind() else { + return; + }; + if !self.tcx.is_diagnostic_item(sym::Option, callee_adt.did()) { + return; + } + + if call_ident.map_or(true, |ident| ident.name != sym::unwrap_or) { + return; + } + + let ty::Ref(_, peeled, _mutability) = provided_ty.kind() else { + return; + }; + + // NOTE: Can we reuse `suggest_deref_or_ref`? + + // Create an dummy type `&[_]` so that both &[] and `&Vec<T>` can coerce to it. + let dummy_ty = if let ty::Array(elem_ty, size) = peeled.kind() + && let ty::Infer(_) = elem_ty.kind() + && size.try_eval_target_usize(self.tcx, self.param_env) == Some(0) + { + let slice = Ty::new_slice(self.tcx, *elem_ty); + Ty::new_imm_ref(self.tcx, self.tcx.lifetimes.re_static, slice) + } else { + provided_ty + }; + + if !self.can_coerce(expected_ty, dummy_ty) { + return; + } + let (provided_snip, applicability) = + match self.tcx.sess.source_map().span_to_snippet(provided_expr.span) { + Ok(snip) => (snip, Applicability::MachineApplicable), + Err(_) => ("/* _ */".to_owned(), Applicability::MaybeIncorrect), + }; + let sugg = &format!("map_or({provided_snip}, |v| v)"); + err.span_suggestion_verbose( + error_span, + "use `Option::map_or` to deref inner value of `Option`", + sugg, + applicability, + ); + return; + } + /// Suggest wrapping the block in square brackets instead of curly braces /// in case the block was mistaken array syntax, e.g. `{ 1 }` -> `[ 1 ]`. pub(crate) fn suggest_block_to_brackets( diff --git a/tests/ui/mismatched_types/transforming-option-ref-issue-127545.stderr b/tests/ui/mismatched_types/transforming-option-ref-issue-127545.stderr index 2d4f26c388d..90a7cfdb449 100644 --- a/tests/ui/mismatched_types/transforming-option-ref-issue-127545.stderr +++ b/tests/ui/mismatched_types/transforming-option-ref-issue-127545.stderr @@ -13,7 +13,7 @@ help: try using `.map(|v| &**v)` to convert `Option<&Vec<i32>>` to `Option<&[i32 LL | arg.map(|v| &**v) | ++++++++++++++ -error: aborting due to 1 previous error +error[E0308]: mismatched types --> $DIR/transforming-option-ref-issue-127545.rs:9:19 | LL | arg.unwrap_or(&[]) @@ -32,6 +32,10 @@ LL | arg.unwrap_or(&[]) | this argument influences the return type of `unwrap_or` note: method defined here --> $SRC_DIR/core/src/option.rs:LL:COL +help: use `Option::map_or` to deref inner value of `Option` + | +LL | arg.map_or(&[], |v| v) + | ~~~~~~~~~~~~~~~~~~ error[E0308]: mismatched types --> $DIR/transforming-option-ref-issue-127545.rs:13:19 @@ -52,6 +56,10 @@ LL | arg.unwrap_or(v) | this argument influences the return type of `unwrap_or` note: method defined here --> $SRC_DIR/core/src/option.rs:LL:COL +help: use `Option::map_or` to deref inner value of `Option` + | +LL | arg.map_or(v, |v| v) + | ~~~~~~~~~~~~~~~~ error: aborting due to 3 previous errors |