Remove a now-useless field

Author: oli-obk

compiler/rustc_typeck/src/check/_match.rs

@@ -4,7 +4,7 @@ use rustc_errors::{Applicability, DiagnosticBuilder};
 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, TyS};
+use rustc_middle::ty::{self, ToPredicate, Ty, TyS, TypeFoldable};
 use rustc_span::{MultiSpan, Span};
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
 use rustc_trait_selection::traits::{
@@ -506,9 +506,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         outer_ty: &'tcx TyS<'tcx>,
         orig_expected: Expectation<'tcx>,
     ) -> Option<Span> {
-        match (orig_expected, self.ret_coercion_impl_trait.map(|ty| (self.body_id.owner, ty))) {
-            (Expectation::ExpectHasType(expected), Some(_))
-                if self.in_tail_expr && self.can_coerce(outer_ty, expected) =>
+        match orig_expected {
+            Expectation::ExpectHasType(expected)
+                if self.in_tail_expr
+                    && self.ret_coercion.as_ref()?.borrow().merged_ty().has_opaque_types()
+                    && self.can_coerce(outer_ty, expected) =>
             {
                 let obligations = self.fulfillment_cx.borrow().pending_obligations();
                 let mut suggest_box = !obligations.is_empty();

compiler/rustc_typeck/src/check/check.rs

@@ -95,11 +95,6 @@ pub(super) fn check_fn<'a, 'tcx>(
 
     fcx.ret_coercion = Some(RefCell::new(CoerceMany::new(declared_ret_ty)));
     fcx.ret_type_span = Some(decl.output.span());
-    if let ty::Opaque(..) = declared_ret_ty.kind() {
-        // FIXME(oli-obk): remove this and have diagnostics check the signature's return type directly
-        // as we don't reveal here anymore.
-        fcx.ret_coercion_impl_trait = Some(declared_ret_ty);
-    }
 
     let span = body.value.span;
 

compiler/rustc_typeck/src/check/fn_ctxt/mod.rs

@@ -57,8 +57,6 @@ pub struct FnCtxt<'a, 'tcx> {
     /// any).
     pub(super) ret_coercion: Option<RefCell<DynamicCoerceMany<'tcx>>>,
 
-    pub(super) ret_coercion_impl_trait: Option<Ty<'tcx>>,
-
     pub(super) ret_type_span: Option<Span>,
 
     /// Used exclusively to reduce cost of advanced evaluation used for
@@ -130,7 +128,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             param_env,
             err_count_on_creation: inh.tcx.sess.err_count(),
             ret_coercion: None,
-            ret_coercion_impl_trait: None,
             ret_type_span: None,
             in_tail_expr: false,
             ret_coercion_span: Cell::new(None),