Avoid a bunch of booleans in favor of Result<(), ErrorGuaranteed> as that more robustly proves that an error has been emitted

compiler/rustc_hir_typeck/src/expr.rs

@@ -1341,16 +1341,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 self.write_method_call_and_enforce_effects(expr.hir_id, expr.span, method);
                 Ok(method)
             }
-            Err(error) => {
+            Err(error) => Err(if segment.ident.name == kw::Empty {
-                if segment.ident.name != kw::Empty {
+                self.dcx().span_delayed_bug(rcvr.span, "empty method name")
-                    if let Some(err) =
+            } else {
-                        self.report_method_error(expr.hir_id, rcvr_t, error, expected, false)
+                match self.report_method_error(expr.hir_id, rcvr_t, error, expected, false) {
-                    {
+                    Ok(diag) => diag.emit(),
-                        err.emit();
+                    Err(guar) => guar,
-                    }
                 }
-                Err(())
+            }),
-            }
         };
 
         // Call the generic checker.

compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

@@ -846,15 +846,14 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 }
 
                 if item_name.name != kw::Empty {
-                    if let Some(e) = self.report_method_error(
+                    self.report_method_error(
                         hir_id,
                         ty.normalized,
                         error,
                         Expectation::NoExpectation,
                         trait_missing_method && span.edition().at_least_rust_2021(), // emits missing method for trait only after edition 2021
-                    ) {
+                    )?
-                        e.emit();
+                    .emit();
-                    }
                 }
 
                 result

compiler/rustc_hir_typeck/src/fn_ctxt/checks.rs

@@ -113,16 +113,16 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         &self,
         sp: Span,
         expr: &'tcx hir::Expr<'tcx>,
-        method: Result<MethodCallee<'tcx>, ()>,
+        method: Result<MethodCallee<'tcx>, ErrorGuaranteed>,
         args_no_rcvr: &'tcx [hir::Expr<'tcx>],
         tuple_arguments: TupleArgumentsFlag,
         expected: Expectation<'tcx>,
     ) -> Ty<'tcx> {
         let has_error = match method {
-            Ok(method) => method.args.references_error() || method.sig.references_error(),
+            Ok(method) => method.args.error_reported().and(method.sig.error_reported()),
-            Err(_) => true,
+            Err(guar) => Err(guar),
         };
-        if has_error {
+        if let Err(guar) = has_error {
             let err_inputs = self.err_args(args_no_rcvr.len());
 
             let err_inputs = match tuple_arguments {
@@ -140,7 +140,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 tuple_arguments,
                 method.ok().map(|method| method.def_id),
             );
-            return Ty::new_misc_error(self.tcx);
+            return Ty::new_error(self.tcx, guar);
         }
 
         let method = method.unwrap();

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -33,7 +33,7 @@ use rustc_middle::ty::IsSuggestable;
 use rustc_middle::ty::{self, GenericArgKind, Ty, TyCtxt, TypeVisitableExt};
 use rustc_span::def_id::DefIdSet;
 use rustc_span::symbol::{kw, sym, Ident};
-use rustc_span::{edit_distance, ExpnKind, FileName, MacroKind, Span};
+use rustc_span::{edit_distance, ErrorGuaranteed, ExpnKind, FileName, MacroKind, Span};
 use rustc_span::{Symbol, DUMMY_SP};
 use rustc_trait_selection::infer::InferCtxtExt;
 use rustc_trait_selection::traits::error_reporting::on_unimplemented::OnUnimplementedNote;
@@ -192,7 +192,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         error: MethodError<'tcx>,
         expected: Expectation<'tcx>,
         trait_missing_method: bool,
-    ) -> Option<Diag<'_>> {
+    ) -> Result<Diag<'_>, ErrorGuaranteed> {
         let (span, sugg_span, source, item_name, args) = match self.tcx.hir_node(call_id) {
             hir::Node::Expr(&hir::Expr {
                 kind: hir::ExprKind::MethodCall(segment, rcvr, args, _),
@@ -226,9 +226,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         };
 
         // Avoid suggestions when we don't know what's going on.
-        if rcvr_ty.references_error() {
+        rcvr_ty.error_reported()?;
-            return None;
-        }
 
         match error {
             MethodError::NoMatch(mut no_match_data) => {
@@ -265,7 +263,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     &mut sources,
                     Some(sugg_span),
                 );
-                err.emit();
+                return Err(err.emit());
             }
 
             MethodError::PrivateMatch(kind, def_id, out_of_scope_traits) => {
@@ -286,7 +284,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     .unwrap_or_else(|| self.tcx.def_span(def_id));
                 err.span_label(sp, format!("private {kind} defined here"));
                 self.suggest_valid_traits(&mut err, item_name, out_of_scope_traits, true);
-                err.emit();
+                return Err(err.emit());
             }
 
             MethodError::IllegalSizedBound { candidates, needs_mut, bound_span, self_expr } => {
@@ -343,12 +341,11 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                         }
                     }
                 }
-                err.emit();
+                return Err(err.emit());
             }
 
             MethodError::BadReturnType => bug!("no return type expectations but got BadReturnType"),
         }
-        None
     }
 
     fn suggest_missing_writer(&self, rcvr_ty: Ty<'tcx>, rcvr_expr: &hir::Expr<'tcx>) -> Diag<'_> {
@@ -576,7 +573,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         no_match_data: &mut NoMatchData<'tcx>,
         expected: Expectation<'tcx>,
         trait_missing_method: bool,
-    ) -> Option<Diag<'_>> {
+    ) -> Result<Diag<'_>, ErrorGuaranteed> {
         let mode = no_match_data.mode;
         let tcx = self.tcx;
         let rcvr_ty = self.resolve_vars_if_possible(rcvr_ty);
@@ -608,14 +605,15 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
 
         // We could pass the file for long types into these two, but it isn't strictly necessary
         // given how targeted they are.
-        if self.suggest_wrapping_range_with_parens(
+        self.suggest_wrapping_range_with_parens(
             tcx,
             rcvr_ty,
             source,
             span,
             item_name,
             &short_ty_str,
-        ) || self.suggest_constraining_numerical_ty(
+        )?;
+        self.suggest_constraining_numerical_ty(
             tcx,
             rcvr_ty,
             source,
@@ -623,9 +621,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             item_kind,
             item_name,
             &short_ty_str,
-        ) {
+        )?;
-            return None;
-        }
         span = item_name.span;
 
         // Don't show generic arguments when the method can't be found in any implementation (#81576).
@@ -881,7 +877,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 vec![(span.shrink_to_lo(), format!("into_iter()."))],
                 Applicability::MaybeIncorrect,
             );
-            return Some(err);
+            return Ok(err);
         } else if !unsatisfied_predicates.is_empty() && matches!(rcvr_ty.kind(), ty::Param(_)) {
             // We special case the situation where we are looking for `_` in
             // `<TypeParam as _>::method` because otherwise the machinery will look for blanket
@@ -1606,7 +1602,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
 
         self.note_derefed_ty_has_method(&mut err, source, rcvr_ty, item_name, expected);
-        Some(err)
+        Ok(err)
     }
 
     /// If an appropriate error source is not found, check method chain for possible candidates
@@ -2259,7 +2255,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         span: Span,
         item_name: Ident,
         ty_str: &str,
-    ) -> bool {
+    ) -> Result<(), ErrorGuaranteed> {
         if let SelfSource::MethodCall(expr) = source {
             for (_, parent) in tcx.hir().parent_iter(expr.hir_id).take(5) {
                 if let Node::Expr(parent_expr) = parent {
@@ -2316,7 +2312,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     );
                     if pick.is_ok() {
                         let range_span = parent_expr.span.with_hi(expr.span.hi());
-                        tcx.dcx().emit_err(errors::MissingParenthesesInRange {
+                        return Err(tcx.dcx().emit_err(errors::MissingParenthesesInRange {
                             span,
                             ty_str: ty_str.to_string(),
                             method_name: item_name.as_str().to_string(),
@@ -2325,13 +2321,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                 left: range_span.shrink_to_lo(),
                                 right: range_span.shrink_to_hi(),
                             }),
-                        });
+                        }));
-                        return true;
                     }
                 }
             }
         }
-        false
+        Ok(())
     }
 
     fn suggest_constraining_numerical_ty(
@@ -2343,7 +2338,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         item_kind: &str,
         item_name: Ident,
         ty_str: &str,
-    ) -> bool {
+    ) -> Result<(), ErrorGuaranteed> {
         let found_candidate = all_traits(self.tcx)
             .into_iter()
             .any(|info| self.associated_value(info.def_id, item_name).is_some());
@@ -2447,10 +2442,9 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                 }
                 _ => {}
             }
-            err.emit();
+            return Err(err.emit());
-            return true;
         }
-        false
+        Ok(())
     }
 
     /// For code `rect::area(...)`,