diff options
Diffstat (limited to 'compiler')
| -rw-r--r-- | compiler/rustc_hir_typeck/src/_match.rs | 123 | ||||
| -rw-r--r-- | compiler/rustc_hir_typeck/src/check.rs | 2 | ||||
| -rw-r--r-- | compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs | 5 |
3 files changed, 73 insertions, 57 deletions
diff --git a/compiler/rustc_hir_typeck/src/_match.rs b/compiler/rustc_hir_typeck/src/_match.rs index 2b15d4dcd08..2290ac948f0 100644 --- a/compiler/rustc_hir_typeck/src/_match.rs +++ b/compiler/rustc_hir_typeck/src/_match.rs @@ -1,6 +1,6 @@ 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; @@ -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>]) { diff --git a/compiler/rustc_hir_typeck/src/check.rs b/compiler/rustc_hir_typeck/src/check.rs index b706d786b52..3b0b00f2aba 100644 --- a/compiler/rustc_hir_typeck/src/check.rs +++ b/compiler/rustc_hir_typeck/src/check.rs @@ -142,7 +142,6 @@ pub(super) fn check_fn<'a, 'tcx>( inherited.typeck_results.borrow_mut().liberated_fn_sigs_mut().insert(fn_id, fn_sig); - fcx.in_tail_expr = true; if let ty::Dynamic(..) = declared_ret_ty.kind() { // FIXME: We need to verify that the return type is `Sized` after the return expression has // been evaluated so that we have types available for all the nodes being returned, but that @@ -161,7 +160,6 @@ pub(super) fn check_fn<'a, 'tcx>( fcx.require_type_is_sized(declared_ret_ty, decl.output.span(), traits::SizedReturnType); fcx.check_return_expr(&body.value, false); } - fcx.in_tail_expr = false; // We insert the deferred_generator_interiors entry after visiting the body. // This ensures that all nested generators appear before the entry of this generator. diff --git a/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs b/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs index c36c01e1b46..02b3e06d902 100644 --- a/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs +++ b/compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs @@ -68,10 +68,6 @@ pub struct FnCtxt<'a, 'tcx> { /// any). pub(super) ret_coercion: Option<RefCell<DynamicCoerceMany<'tcx>>>, - /// Used exclusively to reduce cost of advanced evaluation used for - /// more helpful diagnostics. - pub(super) in_tail_expr: bool, - /// First span of a return site that we find. Used in error messages. pub(super) ret_coercion_span: Cell<Option<Span>>, @@ -140,7 +136,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> { param_env, err_count_on_creation: inh.tcx.sess.err_count(), ret_coercion: None, - in_tail_expr: false, ret_coercion_span: Cell::new(None), resume_yield_tys: None, ps: Cell::new(UnsafetyState::function(hir::Unsafety::Normal, hir::CRATE_HIR_ID)), |