diff options
Diffstat (limited to '')
-rw-r--r-- | compiler/rustc_hir_typeck/src/_match.rs | 160 |
1 files changed, 89 insertions, 71 deletions
diff --git a/compiler/rustc_hir_typeck/src/_match.rs b/compiler/rustc_hir_typeck/src/_match.rs index 2b15d4dcd..e25a9e903 100644 --- a/compiler/rustc_hir_typeck/src/_match.rs +++ b/compiler/rustc_hir_typeck/src/_match.rs @@ -1,10 +1,10 @@ use crate::coercion::{AsCoercionSite, CoerceMany}; use crate::{Diverges, Expectation, FnCtxt, Needs}; -use rustc_errors::{Applicability, MultiSpan}; +use rustc_errors::{Applicability, Diagnostic, MultiSpan}; use rustc_hir::{self as hir, ExprKind}; use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; use rustc_infer::traits::Obligation; -use rustc_middle::ty::{self, ToPredicate, Ty}; +use rustc_middle::ty::{self, Ty}; use rustc_span::Span; use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt; use rustc_trait_selection::traits::{ @@ -137,55 +137,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { Some(&arm.body), arm_ty, Some(&mut |err| { - let Some(ret) = self - .tcx - .hir() - .find_by_def_id(self.body_id.owner.def_id) - .and_then(|owner| owner.fn_decl()) - .map(|decl| decl.output.span()) - else { return; }; - let Expectation::IsLast(stmt) = orig_expected else { - return - }; - let can_coerce_to_return_ty = match self.ret_coercion.as_ref() { - Some(ret_coercion) if self.in_tail_expr => { - let ret_ty = ret_coercion.borrow().expected_ty(); - let ret_ty = self.inh.infcx.shallow_resolve(ret_ty); - self.can_coerce(arm_ty, ret_ty) - && prior_arm.map_or(true, |(_, t, _)| self.can_coerce(t, ret_ty)) - // The match arms need to unify for the case of `impl Trait`. - && !matches!(ret_ty.kind(), ty::Opaque(..)) - } - _ => false, - }; - if !can_coerce_to_return_ty { - return; - } - - let semi_span = expr.span.shrink_to_hi().with_hi(stmt.hi()); - let mut ret_span: MultiSpan = semi_span.into(); - ret_span.push_span_label( - expr.span, - "this could be implicitly returned but it is a statement, not a \ - tail expression", - ); - ret_span - .push_span_label(ret, "the `match` arms can conform to this return type"); - ret_span.push_span_label( - semi_span, - "the `match` is a statement because of this semicolon, consider \ - removing it", - ); - err.span_note( - ret_span, - "you might have meant to return the `match` expression", - ); - err.tool_only_span_suggestion( - semi_span, - "remove this semicolon", - "", - Applicability::MaybeIncorrect, - ); + self.suggest_removing_semicolon_for_coerce( + err, + expr, + orig_expected, + arm_ty, + prior_arm, + ) }), false, ); @@ -219,6 +177,71 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { coercion.complete(self) } + fn suggest_removing_semicolon_for_coerce( + &self, + diag: &mut Diagnostic, + expr: &hir::Expr<'tcx>, + expectation: Expectation<'tcx>, + arm_ty: Ty<'tcx>, + prior_arm: Option<(Option<hir::HirId>, Ty<'tcx>, Span)>, + ) { + let hir = self.tcx.hir(); + + // First, check that we're actually in the tail of a function. + let hir::Node::Expr(hir::Expr { kind: hir::ExprKind::Block(block, _), .. }) = + hir.get(self.body_id) else { return; }; + let Some(hir::Stmt { kind: hir::StmtKind::Semi(last_expr), .. }) + = block.innermost_block().stmts.last() else { return; }; + if last_expr.hir_id != expr.hir_id { + return; + } + + // Next, make sure that we have no type expectation. + let Some(ret) = hir + .find_by_def_id(self.body_id.owner.def_id) + .and_then(|owner| owner.fn_decl()) + .map(|decl| decl.output.span()) else { return; }; + let Expectation::IsLast(stmt) = expectation else { + return; + }; + + let can_coerce_to_return_ty = match self.ret_coercion.as_ref() { + Some(ret_coercion) => { + let ret_ty = ret_coercion.borrow().expected_ty(); + let ret_ty = self.inh.infcx.shallow_resolve(ret_ty); + self.can_coerce(arm_ty, ret_ty) + && prior_arm.map_or(true, |(_, ty, _)| self.can_coerce(ty, ret_ty)) + // The match arms need to unify for the case of `impl Trait`. + && !matches!(ret_ty.kind(), ty::Opaque(..)) + } + _ => false, + }; + if !can_coerce_to_return_ty { + return; + } + + let semi_span = expr.span.shrink_to_hi().with_hi(stmt.hi()); + let mut ret_span: MultiSpan = semi_span.into(); + ret_span.push_span_label( + expr.span, + "this could be implicitly returned but it is a statement, not a \ + tail expression", + ); + ret_span.push_span_label(ret, "the `match` arms can conform to this return type"); + ret_span.push_span_label( + semi_span, + "the `match` is a statement because of this semicolon, consider \ + removing it", + ); + diag.span_note(ret_span, "you might have meant to return the `match` expression"); + diag.tool_only_span_suggestion( + semi_span, + "remove this semicolon", + "", + Applicability::MaybeIncorrect, + ); + } + /// When the previously checked expression (the scrutinee) diverges, /// warn the user about the match arms being unreachable. fn warn_arms_when_scrutinee_diverges(&self, arms: &'tcx [hir::Arm<'tcx>]) { @@ -491,11 +514,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { .. } = self.type_var_origin(expected)? else { return None; }; - let sig = *self - .typeck_results - .borrow() - .liberated_fn_sigs() - .get(hir::HirId::make_owner(self.body_id.owner.def_id))?; + let sig = self.body_fn_sig()?; let substs = sig.output().walk().find_map(|arg| { if let ty::GenericArgKind::Type(ty) = arg.unpack() @@ -519,23 +538,25 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { .bound_explicit_item_bounds(rpit_def_id) .subst_iter_copied(self.tcx, substs) { - let pred = match pred.kind().skip_binder() { - ty::PredicateKind::Trait(mut trait_pred) => { + let pred = pred.kind().rebind(match pred.kind().skip_binder() { + ty::PredicateKind::Clause(ty::Clause::Trait(trait_pred)) => { assert_eq!(trait_pred.trait_ref.self_ty(), opaque_ty); - trait_pred.trait_ref.substs = - self.tcx.mk_substs_trait(ty, &trait_pred.trait_ref.substs[1..]); - pred.kind().rebind(trait_pred).to_predicate(self.tcx) + ty::PredicateKind::Clause(ty::Clause::Trait( + trait_pred.with_self_type(self.tcx, ty), + )) } - ty::PredicateKind::Projection(mut proj_pred) => { + ty::PredicateKind::Clause(ty::Clause::Projection(mut proj_pred)) => { assert_eq!(proj_pred.projection_ty.self_ty(), opaque_ty); - proj_pred.projection_ty.substs = self - .tcx - .mk_substs_trait(ty, &proj_pred.projection_ty.substs[1..]); - pred.kind().rebind(proj_pred).to_predicate(self.tcx) + proj_pred.projection_ty.substs = self.tcx.mk_substs_trait( + ty, + proj_pred.projection_ty.substs.iter().skip(1), + ); + ty::PredicateKind::Clause(ty::Clause::Projection(proj_pred)) } _ => continue, - }; + }); if !self.predicate_must_hold_modulo_regions(&Obligation::new( + self.tcx, ObligationCause::misc(span, self.body_id), self.param_env, pred, @@ -553,8 +574,5 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { } fn arms_contain_ref_bindings<'tcx>(arms: &'tcx [hir::Arm<'tcx>]) -> Option<hir::Mutability> { - arms.iter().filter_map(|a| a.pat.contains_explicit_ref_binding()).max_by_key(|m| match *m { - hir::Mutability::Mut => 1, - hir::Mutability::Not => 0, - }) + arms.iter().filter_map(|a| a.pat.contains_explicit_ref_binding()).max() } |