diff --git a/compiler/error_sort.m b/compiler/error_sort.m
index 5f5ad2224..aa5845292 100644
--- a/compiler/error_sort.m
+++ b/compiler/error_sort.m
@@ -74,74 +74,89 @@
 :- import_module bool.
 :- import_module getopt.
 :- import_module maybe.
+:- import_module require.
 :- import_module term_context.
 
 %---------------------------------------------------------------------------%
 
 standardize_error_specs(Specs, StdSpecs) :-
-    list.filter_map(standardize_error_spec, Specs, StdSpecs).
+    list.map(standardize_error_spec, Specs, StdSpecs).
 
-:- pred standardize_error_spec(error_spec::in, std_error_spec::out) is semidet.
+:- pred standardize_error_spec(error_spec::in, std_error_spec::out) is det.
 
 standardize_error_spec(Spec0, StdSpec) :-
-    require_det (
-        (
-            Spec0 = error_spec(Id, Severity, Phase, Msgs0),
-            list.filter_map(standardize_error_msg, Msgs0, StdMsgs)
-        ;
-            Spec0 = spec(Id, Severity, Phase, Context0, Pieces0),
-            StdMsgs = [error_msg(yes(Context0), treat_based_on_posn, 0u,
-                [always(Pieces0)])]
-        ;
-            Spec0 = no_ctxt_spec(Id, Severity, Phase, Pieces0),
-            StdMsgs = [error_msg(no, treat_based_on_posn, 0u,
-                [always(Pieces0)])]
-        )
+    (
+        Spec0 = error_spec(Id, Severity, Phase, Msgs0),
+        list.map(standardize_error_msg, Msgs0, StdMsgs)
+    ;
+        Spec0 = spec(Id, Severity, Phase, Context0, Pieces0),
+        StdMsgs = [error_msg(yes(Context0), treat_based_on_posn, 0u,
+            [always(Pieces0)])]
+    ;
+        Spec0 = no_ctxt_spec(Id, Severity, Phase, Pieces0),
+        StdMsgs = [error_msg(no, treat_based_on_posn, 0u,
+            [always(Pieces0)])]
     ),
     (
+        StdMsgs = [],
+        unexpected($pred, "StdMsgs = []")
+    ;
         StdMsgs = [_ | _],
         StdSpec = error_spec(Id, Severity, Phase, StdMsgs)
-    ;
-        StdMsgs = [],
-        % Spec0 would result in nothing being printed.
-        fail
     ).
 
-:- pred standardize_error_msg(error_msg::in, std_error_msg::out) is semidet.
+:- pred standardize_error_msg(error_msg::in, std_error_msg::out) is det.
 
 standardize_error_msg(Msg0, StdMsg) :-
-    require_det (
-        (
-            Msg0 = msg(Context, Pieces0),
-            MaybeContext = yes(Context),
-            TreatAsFirst = treat_based_on_posn,
-            ExtraIndent = 0u,
-            StdComponents = [always(Pieces0)]
-        ;
-            Msg0 = no_ctxt_msg(Pieces0),
-            MaybeContext = no,
-            TreatAsFirst = treat_based_on_posn,
-            ExtraIndent = 0u,
-            StdComponents = [always(Pieces0)]
-        ;
-            Msg0 = simple_msg(Context, StdComponents),
-            MaybeContext = yes(Context),
-            TreatAsFirst = treat_based_on_posn,
-            ExtraIndent = 0u
-        ;
-            Msg0 = error_msg(MaybeContext, TreatAsFirst, ExtraIndent,
-                StdComponents)
-        ;
-            Msg0 = blank_msg(MaybeContext),
-            TreatAsFirst = always_treat_as_first,
-            ExtraIndent = 0u,
-            StdComponents = [always([blank_line])]
-        ),
+    (
+        Msg0 = msg(Context, Pieces0),
+        MaybeContext = yes(Context),
+        TreatAsFirst = treat_based_on_posn,
+        ExtraIndent = 0u,
+        StdComponents = [always(Pieces0)]
+    ;
+        Msg0 = no_ctxt_msg(Pieces0),
+        MaybeContext = no,
+        TreatAsFirst = treat_based_on_posn,
+        ExtraIndent = 0u,
+        StdComponents = [always(Pieces0)]
+    ;
+        Msg0 = simple_msg(Context, StdComponents),
+        MaybeContext = yes(Context),
+        TreatAsFirst = treat_based_on_posn,
+        ExtraIndent = 0u
+    ;
+        Msg0 = error_msg(MaybeContext, TreatAsFirst, ExtraIndent,
+            StdComponents)
+    ;
+        Msg0 = blank_msg(MaybeContext),
+        TreatAsFirst = always_treat_as_first,
+        ExtraIndent = 0u,
+        StdComponents = [always([blank_line])]
+    ),
+    (
+        StdComponents = [],
+        % In this situation, we used to just fail, making both this predicate,
+        % and its caller standardize_error_spec, semidet.
+        %
+        % This was when we still had error_msgs that were conditional on
+        % the value of an option. Ever since we moved all such conditionality
+        % to the top level (to the severity of the error_spec), we never delete
+        % any error_msgs from an error_spec. The only way that execution can
+        % *now* get here is if the error_spec was *constructed* with zero
+        % components. That would be a bug, which we catch here.
+        %
+        % We *could* use the type system to enforce the "no empty list of
+        % components" rule, but the type analysis system cannot handle
+        % any subtype of the list type with acceptable performance, and
+        % using the one_or_more type instead in error_specs would be
+        % inconvenient.
+        unexpected($pred, "StdComponents = []")
+    ;
+        StdComponents = [_ | _],
         StdMsg = error_msg(MaybeContext, TreatAsFirst,
             ExtraIndent, StdComponents)
-    ),
-    % Don't return StdMsg if StdComponents is empty.
-    StdComponents = [_ | _].
+    ).
 
 %---------------------------------------------------------------------------%
 
diff --git a/compiler/error_spec.m b/compiler/error_spec.m
index c71caeaf9..5b3e32b5e 100644
--- a/compiler/error_spec.m
+++ b/compiler/error_spec.m
@@ -606,6 +606,8 @@
 
 :- pred extract_spec_phase(error_spec::in, spec_phase::out) is det.
 
+:- pred extract_spec_severity(error_spec::in, spec_severity::out) is det.
+
 :- pred accumulate_contexts(error_spec::in,
     set(prog_context)::in, set(prog_context)::out) is det.
 
@@ -999,6 +1001,15 @@ extract_spec_phase(Spec, Phase) :-
         Spec = no_ctxt_spec(_, _, Phase, _)
     ).
 
+extract_spec_severity(Spec, Severity) :-
+    (
+        Spec = error_spec(_, Severity, _, _)
+    ;
+        Spec = spec(_, Severity, _, _, _)
+    ;
+        Spec = no_ctxt_spec(_, Severity, _, _)
+    ).
+
 accumulate_contexts(Spec, !Contexts) :-
     (
         Spec = error_spec(_, _, _, Msgs),
diff --git a/compiler/make_hlds_error.m b/compiler/make_hlds_error.m
index ad7eeb12e..4dcd27277 100644
--- a/compiler/make_hlds_error.m
+++ b/compiler/make_hlds_error.m
@@ -306,7 +306,7 @@ maybe_report_undefined_pred_error(ModuleInfo, PredOrFunc, SymName,
         module_info_get_predicate_table(ModuleInfo, PredicateTable),
         predicate_table_lookup_pf_sym(PredicateTable,
             is_fully_qualified, PredOrFunc, SymName, AllArityPredIds),
-        gather_porf_arities(ModuleInfo, AllArityPredIds, PredOrFunc,
+        gather_porf_arities(ModuleInfo, PredOrFunc, AllArityPredIds,
             PorFArities),
         set.delete(PredFormArity, PorFArities, OtherPredFormArities),
         % The sorting is to make the error message easier to read.
@@ -316,7 +316,21 @@ maybe_report_undefined_pred_error(ModuleInfo, PredOrFunc, SymName,
         FullPredOrFuncStr = pred_or_func_to_full_str(PredOrFunc),
         (
             OtherPredFormAritiesList = [],
-            Spec = error_spec($pred, severity_error, phase_pt2h, [MainMsg])
+            (
+                InferTypes = no,
+                VerbosePieces = [words("(Use"), quote("--infer-types"),
+                    words("to enable type inference.)"), nl],
+                InferMsg = simple_msg(Context,
+                    [always(MainPieces),
+                    verbose_only(verbose_once, VerbosePieces)]),
+                Spec = error_spec($pred, severity_error, phase_pt2h,
+                    [InferMsg])
+            ;
+                InferTypes = yes,
+                % Any reminder about type inference would be redundant.
+                Spec = spec($pred, severity_error, phase_pt2h,
+                    Context, MainPieces)
+            )
         ;
             (
                 OtherPredFormAritiesList = [OtherPredFormArity],
@@ -350,13 +364,13 @@ maybe_report_undefined_pred_error(ModuleInfo, PredOrFunc, SymName,
     % procedures which have the right pred_or_func field (WantedPorF),
     % and return their original arities.
     %
-:- pred gather_porf_arities(module_info::in, list(pred_id)::in,
-    pred_or_func::in, set(pred_form_arity)::out) is det.
+:- pred gather_porf_arities(module_info::in, pred_or_func::in,
+    list(pred_id)::in, set(pred_form_arity)::out) is det.
 
-gather_porf_arities(_ModuleInfo, [], _WantedPorF, set.init).
-gather_porf_arities(ModuleInfo, [PredId | PredIds], WantedPorF,
+gather_porf_arities(_ModuleInfo, _WantedPorF, [], set.init).
+gather_porf_arities(ModuleInfo, WantedPorF, [PredId | PredIds],
         !:PorFArities) :-
-    gather_porf_arities(ModuleInfo, PredIds, WantedPorF, !:PorFArities),
+    gather_porf_arities(ModuleInfo, WantedPorF, PredIds, !:PorFArities),
     module_info_pred_info(ModuleInfo, PredId, PredInfo),
     PorF = pred_info_is_pred_or_func(PredInfo),
     ( if PorF = WantedPorF then
diff --git a/compiler/mode_errors.m b/compiler/mode_errors.m
index 4a807f0b7..4df0f103f 100644
--- a/compiler/mode_errors.m
+++ b/compiler/mode_errors.m
@@ -665,8 +665,8 @@ mode_error_unify_var_var_to_spec(ModeInfo, X, Y, InstX, InstY) = Spec :-
         [words("variable")] ++
         color_as_subject([quote(mercury_var_to_name_only(VarTable, Y))]) ++
         has_instantiatedness(ModeInfo, yes(color_inconsistent), InstY, "."),
-    Spec = spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode), Context, Preamble ++ Pieces).
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = spec($pred, severity_error, Phase, Context, Preamble ++ Pieces).
 
 %---------------------------------------------------------------------------%
 
@@ -691,8 +691,8 @@ mode_error_unify_var_poly_to_spec(ModeInfo, Var, VarInst) = Spec :-
         words("be ground (or have inst"), quote("any"), suffix(")."),
         words("Unifications of polymorphically-typed variables with"),
         words("partially instantiated modes are not allowed.")],
-    Spec = error_spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode),
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = error_spec($pred, severity_error, Phase,
         [simple_msg(Context,
             [always(Preamble ++ MainPieces),
             verbose_only(verbose_once, VerbosePieces)])]).
@@ -729,8 +729,8 @@ mode_error_unify_var_functor_to_spec(ModeInfo, X, ConsId, ArgVars,
         [words("term")] ++
         color_as_subject([words_quote(FunctorConsIdStr)]) ++
         has_instantiatedness(ModeInfo, InstColor, FakeTermInst, "."),
-    Spec = spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode), Context, Preamble ++ Pieces).
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = spec($pred, severity_error, Phase, Context, Preamble ++ Pieces).
 
 %---------------------------------------------------------------------------%
 
@@ -750,8 +750,8 @@ mode_error_unify_var_lambda_to_spec(ModeInfo, X, InstX, InstY) = Spec :-
         has_instantiatedness(ModeInfo, InstColor, InstX, ",") ++
         color_as_subject([words("lambda expression")]) ++
         has_instantiatedness(ModeInfo, InstColor, InstY, "."),
-    Spec = spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode), Context, Preamble ++ Pieces).
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = spec($pred, severity_error, Phase, Context, Preamble ++ Pieces).
 
 %---------------------------------------------------------------------------%
 
@@ -821,8 +821,9 @@ mode_error_unify_var_multimode_pf_to_spec(ModeInfo, X, PredMultiModeError)
             p_or_f(PredOrFunc), suffix("'s"), words("modes")] ++
             EndPieces ++ [nl]
     ),
-    Spec = spec($pred, severity_error, phase_mode_check(report_in_any_mode),
-        Context, Preamble ++ StartPieces ++ DetailPieces).
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = spec($pred, severity_error, Phase, Context,
+        Preamble ++ StartPieces ++ DetailPieces).
 
 :- func named_and_unnamed_vars_to_pieces(var_table, color_name,
     list(prog_var)) = list(format_piece).
@@ -868,8 +869,8 @@ mode_error_non_ground_non_local_lambda_var_to_spec(ModeInfo, Var, VarInst)
         words("of lambda goals is")] ++
         color_as_correct([quote("ground"), suffix(".")]) ++
         [nl],
-    Spec = spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode), Context, Preamble ++ Pieces).
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = spec($pred, severity_error, Phase, Context, Preamble ++ Pieces).
 
 %---------------------------------------------------------------------------%
 
@@ -919,8 +920,8 @@ mode_error_higher_order_unify_to_spec(ModeInfo, LHSVar, RHS, Type, PredOrFunc)
         words("writing an explicit universal quantification, e.g."),
         quote("all [X] call(PredA, X) <=> call(PredB, X)"), suffix(","),
         words("instead of"), quote("PredA = PredB"), suffix("."), nl],
-    Spec = error_spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode),
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = error_spec($pred, severity_error, Phase,
         [simple_msg(Context,
             [always(Preamble ++ MainPieces),
             verbose_only(verbose_once, VerbosePieces)])]).
@@ -1028,8 +1029,8 @@ mode_error_clobbered_var_is_live_to_spec(ModeInfo, Var) = Spec :-
         [words("is")] ++
         color_as_incorrect([words("still live.")]) ++
         [nl],
-    Spec = spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode), Context, Preamble ++ Pieces).
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = spec($pred, severity_error, Phase, Context, Preamble ++ Pieces).
 
 %---------------------------------------------------------------------------%
 
@@ -1046,8 +1047,8 @@ mode_error_callee_pred_has_no_mode_decl_to_spec(ModeInfo, PredId) = Spec :-
     Pieces = [words("error: there is")] ++
         color_as_incorrect([words("no mode declaration")]) ++
         [words("for")] ++ PredDotPieces ++ [nl],
-    Spec = spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode), Context, Preamble ++ Pieces).
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = spec($pred, severity_error, Phase, Context, Preamble ++ Pieces).
 
 %---------------------------------------------------------------------------%
 
@@ -1770,8 +1771,8 @@ mode_error_merge_par_conj_to_spec(ModeInfo, MergeErrors) = Spec :-
         merge_error_to_msgs(ModeInfo, Context, is_not_disjunctive),
         one_or_more_to_list(MergeErrors)),
     list.condense(MergeMsgLists, MergeMsgs),
-    Spec = error_spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode),
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = error_spec($pred, severity_error, Phase,
         [msg(Context, Preamble ++ MainPieces) | MergeMsgs]).
 
 %---------------------------------------------------------------------------%
@@ -1790,8 +1791,8 @@ mode_error_merge_disj_to_spec(ModeInfo, MergeContext, MergeErrors) = Spec :-
         merge_error_to_msgs(ModeInfo, Context, is_disjunctive),
         one_or_more_to_list(MergeErrors)),
     list.condense(MergeMsgLists, MergeMsgs),
-    Spec = error_spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode),
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = error_spec($pred, severity_error, Phase,
         [msg(Context, Preamble ++ MainPieces) | MergeMsgs]).
 
 :- func merge_context_to_string(merge_context) = string.
@@ -1946,8 +1947,8 @@ mode_error_coerce_error_to_spec(ModeInfo, Errors) = Spec :-
             [words("is not a subtype of"), quote(ToTypeStr), suffix("."), nl]
     ),
     Pieces = [words("mode error:")] ++ TermPathPieces ++ ReasonPieces,
-    Spec = spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode), Context, Preamble ++ Pieces).
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = spec($pred, severity_error, Phase, Context, Preamble ++ Pieces).
 
 :- func make_term_path_piece(coerce_error_term_path_step) =
     list(format_piece).
@@ -2027,8 +2028,8 @@ mode_error_nonground_trace_goal_to_spec(ModeInfo, HeadNGVar, TailNGVars)
         words("expects to get from the surrounding code,"),
         words(IsOrAre)] ++ color_as_incorrect([words("not ground")]) ++
         [words("at entry to the trace goal."), nl],
-    Spec = spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode), Context, Preamble ++ Pieces).
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = spec($pred, severity_error, Phase, Context, Preamble ++ Pieces).
 
 %---------------------------------------------------------------------------%
 
@@ -2119,8 +2120,8 @@ mode_error_bind_locked_var_to_spec(ModeInfo, Reason, Var, VarInst, Inst)
             color_as_incorrect([words("two or more conjuncts.")]) ++
             [nl]
     ),
-    Spec = error_spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode),
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = error_spec($pred, severity_error, Phase,
         [simple_msg(Context,
             [always(Preamble ++ MainPieces),
             verbose_only(verbose_always, VerbosePieces)])]).
@@ -2184,8 +2185,8 @@ mode_error_unexpected_final_inst_to_spec(ModeInfo, RawArgNum, Var,
             report_inst(ModeInfo, quote_short_inst, [suffix("."), nl],
                 [nl_indent_delta(1)], [suffix("."), nl_indent_delta(-1)],
                 ExpectedInst)),
-    Spec = spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode), Context, Preamble ++ Pieces).
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = spec($pred, severity_error, Phase, Context, Preamble ++ Pieces).
 
 %---------------------------------------------------------------------------%
 
@@ -2280,8 +2281,8 @@ mode_error_in_callee_to_spec(!.ModeInfo, Vars, Insts,
             ),
             LaterMsgs = start_each_msg_with_blank_line([LaterHead | LaterTail])
         ),
-        Spec = error_spec($pred, severity_error,
-            phase_mode_check(report_in_any_mode), [InitMsg | LaterMsgs])
+        Phase = phase_mode_check(report_in_any_mode),
+        Spec = error_spec($pred, severity_error, Phase, [InitMsg | LaterMsgs])
     ;
         CalleeModeErrors = [],
         unexpected($pred, "no error")
@@ -2351,8 +2352,8 @@ purity_error_should_be_in_promise_purity_scope_to_spec(NegCtxtDesc,
             [words("has inst")] ++ color_as_incorrect([quote("any")]) ++
             [words("and appears in the body."), nl]
     ),
-    Spec = spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode), Context, Preamble ++ Pieces).
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = spec($pred, severity_error, Phase, Context, Preamble ++ Pieces).
 
 %---------------------------------------------------------------------------%
 
@@ -2390,8 +2391,8 @@ purity_error_lambda_should_be_any_to_spec(ModeInfo, OoMVars) = Spec :-
         words("Function expressions with inst"), quote("any"),
         words("can be written"),
         quote("any_func(Args) = Result is det :- ..."), suffix("."), nl]),
-    Spec = error_spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode),
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = error_spec($pred, severity_error, Phase,
         [simple_msg(Context, [Always, VerboseOnly])]).
 
 %---------------------------------------------------------------------------%
@@ -2705,8 +2706,8 @@ mode_warning_cannot_succeed_var_var(ModeInfo, X, Y, InstX, InstY) = Spec :-
         has_instantiatedness(ModeInfo, MaybeColor, InstX, ",") ++
         color_as_subject([quote(NameY)]) ++
         has_instantiatedness(ModeInfo, MaybeColor, InstY, "."),
-    Spec = spec($pred, severity_warning(warn_dodgy_simple_code),
-        phase_mode_check(report_only_if_in_all_modes),
+    Phase = phase_mode_check(report_only_if_in_all_modes),
+    Spec = spec($pred, severity_warning(warn_dodgy_simple_code), Phase,
         Context, Preamble ++ Pieces).
 
 %---------------------------------------------------------------------------%
@@ -2739,8 +2740,8 @@ mode_warning_cannot_succeed_var_functor(ModeInfo, X, InstX, ConsId) = Spec :-
         [words("cannot succeed."), nl] ++
         color_as_subject([quote(NameX)]) ++
         has_instantiatedness(ModeInfo, yes(color_incorrect), InstX, "."),
-    Spec = spec($pred, severity_warning(warn_dodgy_simple_code),
-        phase_mode_check(report_only_if_in_all_modes),
+    Phase = phase_mode_check(report_only_if_in_all_modes),
+    Spec = spec($pred, severity_warning(warn_dodgy_simple_code), Phase,
         Context, Preamble ++ Pieces).
 
 %---------------------------------------------------------------------------%
@@ -2762,8 +2763,9 @@ mode_warning_cannot_succeed_ground_occur_check(ModeInfo, X, ConsId) = Spec :-
         color_as_incorrect([quote(NameX), words("cannot be equal"),
             words("to a term containing itself.")]) ++
         [nl],
-    Spec = spec($pred, severity_warning(warn_dodgy_simple_code),
-        phase_mode_check(report_in_any_mode), Context, Preamble ++ Pieces).
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = spec($pred, severity_warning(warn_dodgy_simple_code), Phase,
+        Context, Preamble ++ Pieces).
 
 %---------------------------------------------------------------------------%
 %---------------------------------------------------------------------------%
diff --git a/compiler/modes.m b/compiler/modes.m
index 47f00e622..5be88fffb 100644
--- a/compiler/modes.m
+++ b/compiler/modes.m
@@ -558,8 +558,8 @@ report_max_iterations_exceeded(ModuleInfo) = Spec :-
         words("option to increase the limit."),
         words("(The current limit is"), int_fixed(MaxIterations),
         words("iterations.)"), nl],
-    Spec = no_ctxt_spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode), Pieces).
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = no_ctxt_spec($pred, severity_error, Phase, Pieces).
 
     % copy_pred_bodies(OldPredIdTable, ProcId, !ModuleInfo):
     %
@@ -759,33 +759,17 @@ maybe_report_error_no_modes(ModuleInfo, PredId, PredInfo) = Specs :-
             Specs = []
         ;
             InferModesOpt = no,
-            pred_info_get_markers(PredInfo, Markers),
-            ( if marker_is_present(Markers, marker_no_pred_decl) then
-                % Generate an error_spec that prints nothing.
-                % While we don't want the user to see the error message,
-                % we need the severity_error to stop the compiler
-                % from proceeding to process this predicate further.
-                % For example, to determinism analysis, where it could
-                % generate misleading errors about the determinism declaration
-                % (added implicitly by the compiler) being wrong.
-                % There is no risk of the compilation failing without
-                % *any* error indication, since we generated an error message
-                % when we added the marker.
-                Msgs = []
-            else
-                PredDescPieces = describe_one_pred_name(ModuleInfo,
-                    yes(color_subject), should_not_module_qualify, [], PredId),
-                MainPieces = [words("Error:")] ++ PredDescPieces ++
-                    color_as_incorrect([words("has no mode declaration.")]) ++
-                    [nl],
-                VerbosePieces =
-                    [words("(Use"), quote("--infer-modes"),
-                    words("to enable mode inference.)"), nl],
-                Msgs =
-                    [simple_msg(Context,
-                        [always(MainPieces),
-                        verbose_only(verbose_once, VerbosePieces)])]
-            ),
+            PredDescPieces = describe_one_pred_name(ModuleInfo,
+                yes(color_subject), should_not_module_qualify, [], PredId),
+            MainPieces = [words("Error:")] ++ PredDescPieces ++
+                color_as_incorrect([words("has no mode declaration.")]) ++
+                [nl],
+            VerbosePieces = [words("(Use"), quote("--infer-modes"),
+                words("to enable mode inference.)"), nl],
+            Msgs =
+                [simple_msg(Context,
+                    [always(MainPieces),
+                    verbose_only(verbose_once, VerbosePieces)])],
             pred_info_get_context(PredInfo, Context),
             Phase = phase_mode_check(report_in_any_mode),
             Spec = error_spec($pred, severity_error, Phase, Msgs),
@@ -1853,8 +1837,8 @@ report_eval_method_requires_ground_args(ProcInfo, TabledMethod) = Spec :-
         words("is not currently implemented."), nl],
     Msg = simple_msg(Context,
         [always(MainPieces), verbose_only(verbose_once, VerbosePieces)]),
-    Spec = error_spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode), [Msg]).
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = error_spec($pred, severity_error, Phase, [Msg]).
 
 :- func report_eval_method_destroys_uniqueness(proc_info, tabled_eval_method)
     = error_spec.
@@ -1874,8 +1858,8 @@ report_eval_method_destroys_uniqueness(ProcInfo, TabledMethod) = Spec :-
         words("which would destroy their uniqueness."), nl],
     Msg = simple_msg(Context,
         [always(MainPieces), verbose_only(verbose_once, VerbosePieces)]),
-    Spec = error_spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode), [Msg]).
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = error_spec($pred, severity_error, Phase, [Msg]).
 
 :- func report_wrong_mode_for_main(proc_info) = error_spec.
 
@@ -1887,8 +1871,8 @@ report_wrong_mode_for_main(ProcInfo) = Spec :-
         color_as_incorrect([words("must have mode"), quote("(di, uo)"),
             suffix(".")]) ++
         [nl],
-    Spec = spec($pred, severity_error,
-        phase_mode_check(report_in_any_mode), Context, Pieces).
+    Phase = phase_mode_check(report_in_any_mode),
+    Spec = spec($pred, severity_error, Phase, Context, Pieces).
 
 %-----------------------------------------------------------------------------%
 
@@ -2029,8 +2013,8 @@ report_mode_inference_message(ModuleInfo, OutputDetism, PredInfo, ProcInfo,
         ),
         Pieces = [words(Verb), words(Detail), nl],
         Severity = severity_informational(inform_inferred_modes),
-        Spec = spec($pred, Severity, phase_mode_check(report_in_any_mode),
-            Context, Pieces)
+        Phase = phase_mode_check(report_in_any_mode),
+        Spec = spec($pred, Severity, Phase, Context, Pieces)
     ).
 
 %-----------------------------------------------------------------------------%
diff --git a/compiler/opt_format_call_errors.m b/compiler/opt_format_call_errors.m
index a64320618..7cf379217 100644
--- a/compiler/opt_format_call_errors.m
+++ b/compiler/opt_format_call_errors.m
@@ -148,8 +148,8 @@ report_format_mismatch(ModuleInfo, PredId, MaybePos, HeadError, TailErrors,
             words("in call to")] ++ PredNameDotPieces ++ [nl] ++
             ErrorPieces,
         Phase = phase_simplify(report_in_any_mode),
-        Spec = spec($pred, severity_warning(warn_known_bad_format_calls),
-            Phase, Context, Pieces),
+        Severity = severity_warning(warn_known_bad_format_calls),
+        Spec = spec($pred, Severity, Phase, Context, Pieces),
         Specs = [Spec]
     ).
 
diff --git a/compiler/simplify_proc.m b/compiler/simplify_proc.m
index 7b5d12db1..296352cbb 100644
--- a/compiler/simplify_proc.m
+++ b/compiler/simplify_proc.m
@@ -467,7 +467,7 @@ simplify_proc_analyze_and_format_calls(ProgressStream, ImplicitStreamWarnings,
         ImplicitStreamWarnings, !.ModuleInfo, PredInfo0, !.ProcInfo,
         Goal0, MaybeGoal1, FormatSpecs1, VarTable0, VarTable1),
     ( if
-        had_some_unknown_format_calls(FormatSpecs1),
+        had_some_unknown_format_calls(FormatSpecs1) = yes,
         % We found some format calls that we couldn't optimize because
         % we don't know either the format string or the list of values
         % to be printed. Try to fix this by moving copies of the format call
@@ -545,24 +545,15 @@ simplify_proc_analyze_and_format_calls(ProgressStream, ImplicitStreamWarnings,
         % of the goal that we will not be using.
     ).
 
-:- pred had_some_unknown_format_calls(list(error_spec)::in) is semidet.
+:- func had_some_unknown_format_calls(list(error_spec)) = bool.
 
-had_some_unknown_format_calls([]) :-
-    fail.
-had_some_unknown_format_calls([Spec | Specs]) :-
-    require_complete_switch [Spec]
-    (
-        Spec = spec(_, Severity, _, _, _),
-        ( if Severity = severity_warning(warn_unknown_format_calls) then
-            true
-        else
-            had_some_unknown_format_calls(Specs)
-        )
-    ;
-        ( Spec = no_ctxt_spec(_, _, _, _)
-        ; Spec = error_spec(_, _, _, _)
-        ),
-        unexpected($pred, "unexpected form of error_spec")
+had_some_unknown_format_calls([]) = no.
+had_some_unknown_format_calls([Spec | Specs]) = SomeUnknown :-
+    extract_spec_severity(Spec, Severity),
+    ( if Severity = severity_warning(warn_unknown_format_calls) then
+        SomeUnknown = yes
+    else
+        SomeUnknown = had_some_unknown_format_calls(Specs)
     ).
 
 :- pred push_format_calls_into_branches_in_goal(module_info::in,
diff --git a/tests/invalid/Mercury.options b/tests/invalid/Mercury.options
index 5618070bd..5c917bbdd 100644
--- a/tests/invalid/Mercury.options
+++ b/tests/invalid/Mercury.options
@@ -23,12 +23,14 @@ MCFLAGS-bad_ambiguity_msg       += -E
 MCFLAGS-bad_exported_mode       += --infer-all --no-intermodule-optimization
 MCFLAGS-bug150_partial_color    += --ignore-color-scheme-envvar
 MCFLAGS-bug150_partial_color    += --color-scheme specified@incorrect=203
+MCFLAGS-bug113                  += -E
 # Intermodule optimization changes the number of an unnamed variable
 # whose automatically-constructed "name" shows up in the .err file.
 MCFLAGS-bug214                  += --allow-stubs --no-warn-stubs
 MCFLAGS-bug214                  += --no-intermodule-optimization
 # Mantis bug 238 shows up in bug238.m only with --constraint-propagation.
 MCFLAGS-bug238                  += --constraint-propagation
+MCFLAGS-bug476                  += -E
 MCFLAGS-children                += --no-intermodule-optimization
 MCFLAGS-coerce_implied_mode     += --halt-at-warn
 MCFLAGS-coerce_infer            += --infer-all
@@ -70,6 +72,7 @@ MCFLAGS-method_impl             += --warn-too-private-instances
 MCFLAGS-missing_det_decls       += --no-infer-det -E
 MCFLAGS-missing_interface_import2 += --no-intermodule-optimization
 MCFLAGS-mode_inf                += --infer-all -E
+MCFLAGS-mode_without_pred       += -E
 MCFLAGS-mpj_1                   += --infer-all -E
 MCFLAGS-mpj_3                   += --warn-too-private-instances
 MCFLAGS-mpj_4                   += --warn-too-private-instances
@@ -80,6 +83,7 @@ MCFLAGS-overloading             += --no-intermodule-optimization
 MCFLAGS-pragma_c_code_no_det    += --warn-inferred-erroneous
 MCFLAGS-range_restrict          += --warn-too-private-instances
 MCFLAGS-record_syntax_errors    += -E
+MCFLAGS-ref_to_implicit_pred    += -E
 MCFLAGS-string_format_bad       += --halt-at-warn
 MCFLAGS-string_format_bad       += --warn-known-bad-format-calls
 MCFLAGS-string_format_bad       += --warn-unknown-format-calls
@@ -125,6 +129,7 @@ MCFLAGS-one_member              += -E
 MCFLAGS-oisu_check_add_pragma_errors += --no-halt-at-invalid-interface
 MCFLAGS-polymorphic_unification += -E
 MCFLAGS-test_type_spec          += -E
+MCFLAGS-typeclass_mode_2        += -E
 
 MCFLAGS-require_tailrec_1       += -O0 --optimise-tailcalls
 MCFLAGS-require_tailrec_1       += --no-warn-non-tail-recursion
diff --git a/tests/invalid/bug113.err_exp b/tests/invalid/bug113.err_exp
index 63698d475..b00dccb5e 100644
--- a/tests/invalid/bug113.err_exp
+++ b/tests/invalid/bug113.err_exp
@@ -3,6 +3,7 @@ bug113.m:019:   warning: module `list' is imported in the inte
 bug113.m:019:   not used in the interface.
 bug113.m:032: Error: clause for function `new'/1 without a corresponding
 bug113.m:032:   `:- func' declaration.
+bug113.m:032:   (Use `--infer-types' to enable type inference.)
 bug113.m:032: Inferred :- func new(T1) = T2.
 bug113.m:034: Error: clause for function `new'/2 without a corresponding
 bug113.m:034:   `:- func' declaration.
diff --git a/tests/invalid/bug476.err_exp b/tests/invalid/bug476.err_exp
index d7d818b7b..73dc49217 100644
--- a/tests/invalid/bug476.err_exp
+++ b/tests/invalid/bug476.err_exp
@@ -4,3 +4,4 @@ bug476.m:068: Error: the predicate `bug476.mark'/4 is [38;5;2
 bug476.m:034:   Here is its previous definition.
 bug476.m:070: Error: clause for predicate `input_stream_mark'/3 without a
 bug476.m:070:   corresponding `:- pred' declaration.
+bug476.m:070:   (Use `--infer-types' to enable type inference.)
diff --git a/tests/invalid/mode_without_pred.err_exp b/tests/invalid/mode_without_pred.err_exp
index 78d7885c7..d6b1e2b4b 100644
--- a/tests/invalid/mode_without_pred.err_exp
+++ b/tests/invalid/mode_without_pred.err_exp
@@ -1,5 +1,6 @@
 mode_without_pred.m:017: Error: `:- mode' declaration for function `f1'/1
 mode_without_pred.m:017:   without a corresponding `:- func' declaration.
+mode_without_pred.m:017:   (Use `--infer-types' to enable type inference.)
 mode_without_pred.m:017: Inferred :- func f1(mode_without_pred.t) = int.
 mode_without_pred.m:017: In declaration of function `f1'/1:
 mode_without_pred.m:017:   error: a field access function for an exported field
diff --git a/tests/invalid/multimode_syntax.err_exp b/tests/invalid/multimode_syntax.err_exp
index 1361f2de1..674247a33 100644
--- a/tests/invalid/multimode_syntax.err_exp
+++ b/tests/invalid/multimode_syntax.err_exp
@@ -1,6 +1,7 @@
 multimode_syntax.m:015: Error: function `func0'/0 has no clauses.
 multimode_syntax.m:017: Error: clause for predicate `::'/2 without a
 multimode_syntax.m:017:   corresponding `:- pred' declaration.
+multimode_syntax.m:017:   (Use `--infer-types' to enable type inference.)
 multimode_syntax.m:017: In clause for predicate `::'/2:
 multimode_syntax.m:017:   in argument 1 of clause head:
 multimode_syntax.m:017:   error: the language construct `='/2 should be used as
diff --git a/tests/invalid/record_syntax_errors.err_exp b/tests/invalid/record_syntax_errors.err_exp
index 173eb2328..aa2f17797 100644
--- a/tests/invalid/record_syntax_errors.err_exp
+++ b/tests/invalid/record_syntax_errors.err_exp
@@ -1,6 +1,7 @@
 record_syntax_errors.m:027: Error: `:- mode' declaration for function
 record_syntax_errors.m:027:   `field8'/1 without a corresponding `:- func'
 record_syntax_errors.m:027:   declaration.
+record_syntax_errors.m:027:   (Use `--infer-types' to enable type inference.)
 record_syntax_errors.m:027: Inferred :- func field8(record_syntax_errors.cons2)
 record_syntax_errors.m:027:   = int.
 record_syntax_errors.m:033: In DCG field update goal:
diff --git a/tests/invalid/ref_to_implicit_pred.err_exp b/tests/invalid/ref_to_implicit_pred.err_exp
index a3700eacd..a73339881 100644
--- a/tests/invalid/ref_to_implicit_pred.err_exp
+++ b/tests/invalid/ref_to_implicit_pred.err_exp
@@ -3,6 +3,9 @@ ref_to_implicit_pred.m:008:   `test'/0 is not satis
 ref_to_implicit_pred.m:008:   Declared `det', inferred `failure'.
 ref_to_implicit_pred.m:013: Error: clause for predicate `p'/2 without a
 ref_to_implicit_pred.m:013:   corresponding `:- pred' declaration.
+ref_to_implicit_pred.m:013:   (Use `--infer-types' to enable type inference.)
 ref_to_implicit_pred.m:013: Inferred :- pred p((pred), (pred)).
+ref_to_implicit_pred.m:013: Error: predicate `p'/2 has no mode declaration.
+ref_to_implicit_pred.m:013:   (Use `--infer-modes' to enable mode inference.)
 ref_to_implicit_pred.m:014: Error: the predicate or function `p'/2 is
 ref_to_implicit_pred.m:014:   undefined.
diff --git a/tests/invalid/typeclass_mode_2.err_exp b/tests/invalid/typeclass_mode_2.err_exp
index 02842e732..201e51202 100644
--- a/tests/invalid/typeclass_mode_2.err_exp
+++ b/tests/invalid/typeclass_mode_2.err_exp
@@ -2,4 +2,7 @@ typeclass_mode_2.m:009: Error: mode declaration for type class method predicate
 typeclass_mode_2.m:009:   `p'/1 without a corresponding predicate declaration.
 typeclass_mode_2.m:014: Error: clause for predicate `p'/1 without a
 typeclass_mode_2.m:014:   corresponding `:- pred' declaration.
+typeclass_mode_2.m:014:   (Use `--infer-types' to enable type inference.)
 typeclass_mode_2.m:014: Inferred :- pred p(T1).
+typeclass_mode_2.m:014: Error: predicate `p'/1 has no mode declaration.
+typeclass_mode_2.m:014:   (Use `--infer-modes' to enable mode inference.)
diff --git a/tests/invalid/types.err_exp b/tests/invalid/types.err_exp
index 2f868d46f..a05f32535 100644
--- a/tests/invalid/types.err_exp
+++ b/tests/invalid/types.err_exp
@@ -15,6 +15,7 @@ types.m:021:   error: wrong number of arguments (0
 types.m:021:   in call to predicate `p'.
 types.m:023: Error: clause for predicate `r'/0 without a corresponding
 types.m:023:   `:- pred' declaration.
+types.m:023:   (Use `--infer-types' to enable type inference.)
 types.m:024: In clause for predicate `r'/0:
 types.m:024:   error: call to undefined predicate `s'/0.
 types.m:024:   (Did you mean `<', `>', `a', `p', `q', `r' or `z'?)
diff --git a/tests/invalid_nodepend/Mercury.options b/tests/invalid_nodepend/Mercury.options
index 33e2da510..735ac4259 100644
--- a/tests/invalid_nodepend/Mercury.options
+++ b/tests/invalid_nodepend/Mercury.options
@@ -6,8 +6,8 @@ MCFLAGS-bad_foreign_type            += -E
 MCFLAGS-bad_pragma                  += --no-halt-at-invalid-interface
 MCFLAGS-bigtest                     += --no-halt-at-invalid-interface
 MCFLAGS-bigtest                     += -E
-MCFLAGS-bug410                      += --no-warn-unneeded-final-statevars
-MCFLAGS-constrained_poly_insts      += --no-halt-at-invalid-interface
+MCFLAGS-bug410                      += --no-warn-unneeded-final-statevars -E
+MCFLAGS-constrained_poly_insts      += --no-halt-at-invalid-interface -E
 MCFLAGS-duplicate_modes             += -E
 MCFLAGS-errors_1                    += --no-halt-at-invalid-interface
 MCFLAGS-errors_2                    += --no-halt-at-invalid-interface
@@ -23,17 +23,17 @@ MCFLAGS-fundeps_vars                += --no-halt-at-invalid-interface -E
 MCFLAGS-impl_def_literal_syntax     += --no-halt-at-invalid-interface
 MCFLAGS-inst_list_dup               += --no-halt-at-invalid-interface
 MCFLAGS-instance_bug                += -E
-MCFLAGS-invalid_binary_literal      += --no-halt-at-invalid-interface
+MCFLAGS-invalid_binary_literal      += --no-halt-at-invalid-interface -E
 MCFLAGS-invalid_decimal_literal     += --no-halt-at-invalid-interface
-MCFLAGS-invalid_float_literal       += --no-halt-at-invalid-interface
-MCFLAGS-invalid_hex_literal         += --no-halt-at-invalid-interface
+MCFLAGS-invalid_float_literal       += --no-halt-at-invalid-interface -E
+MCFLAGS-invalid_hex_literal         += --no-halt-at-invalid-interface -E
 MCFLAGS-invalid_main                += --no-halt-at-invalid-interface
-MCFLAGS-invalid_octal_literal       += --no-halt-at-invalid-interface
+MCFLAGS-invalid_octal_literal       += --no-halt-at-invalid-interface -E
 MCFLAGS-invalid_typeclass           += --no-halt-at-invalid-interface
 MCFLAGS-kind                        += --no-halt-at-invalid-interface
 MCFLAGS-no_exports                  += --no-halt-at-invalid-interface
 MCFLAGS-no_exports                  += -E --halt-at-warn
-MCFLAGS-null_char                   += --no-halt-at-invalid-interface
+MCFLAGS-null_char                   += --no-halt-at-invalid-interface -E
 MCFLAGS-occurs                      += --no-halt-at-invalid-interface
 MCFLAGS-predmode                    += -E
 MCFLAGS-prog_io_erroneous           += --no-halt-at-invalid-interface -E
@@ -43,11 +43,11 @@ MCFLAGS-reserved_type_name          += --no-halt-at-invalid-interface
 MCFLAGS-specified                   += --no-halt-at-invalid-interface
 MCFLAGS-subtype_invalid_supertype   += --no-halt-at-invalid-interface
 MCFLAGS-test_some                   += --no-halt-at-invalid-interface
-MCFLAGS-test_with_type              += --no-halt-at-invalid-interface
+MCFLAGS-test_with_type              += --no-halt-at-invalid-interface -E
 MCFLAGS-type_vars                   += -E
 MCFLAGS-typeclass_no_param          += --no-halt-at-invalid-interface
 MCFLAGS-typeclass_test_1            += --no-halt-at-invalid-interface
-MCFLAGS-typeclass_test_2            += --no-halt-at-invalid-interface
+MCFLAGS-typeclass_test_2            += --no-halt-at-invalid-interface -E
 MCFLAGS-typeclass_test_3            += --no-halt-at-invalid-interface
 MCFLAGS-typeclass_test_3            += -E
 MCFLAGS-types                       += --no-halt-at-invalid-interface -E
diff --git a/tests/invalid_nodepend/bigtest.err_exp b/tests/invalid_nodepend/bigtest.err_exp
index afd120900..08d194ba3 100644
--- a/tests/invalid_nodepend/bigtest.err_exp
+++ b/tests/invalid_nodepend/bigtest.err_exp
@@ -16,10 +16,12 @@ bigtest.m:006: Error: `export_pred' is not a valid
 bigtest.m:007: Error: `export_type' is not a valid declaration type.
 bigtest.m:009: Error: clause for predicate `fact'/0 without a corresponding
 bigtest.m:009:   `:- pred' declaration.
+bigtest.m:009:   (Use `--infer-types' to enable type inference.)
 bigtest.m:009: Inferred :- pred fact.
+bigtest.m:009: Error: predicate `fact'/0 has no mode declaration.
+bigtest.m:009:   (Use `--infer-modes' to enable mode inference.)
 bigtest.m:010: Syntax error at token ':-': operator precedence error.
 bigtest.m:013: Error: `incorrect_declaration' is not a valid declaration type.
 bigtest.m:015: Error: predicate `p'/1 has no mode declaration.
-bigtest.m:015:   (Use `--infer-modes' to enable mode inference.)
 bigtest.m:030: Error: in definitions of equivalence types, the type name must
 bigtest.m:030:   be followed by `==', not `='.
diff --git a/tests/invalid_nodepend/bug410.err_exp b/tests/invalid_nodepend/bug410.err_exp
index eda5ebd1f..26de428b6 100644
--- a/tests/invalid_nodepend/bug410.err_exp
+++ b/tests/invalid_nodepend/bug410.err_exp
@@ -1,6 +1,9 @@
 bug410.m:055: Error: clause for predicate `make_titles'/3 without a
 bug410.m:055:   corresponding `:- pred' declaration.
+bug410.m:055:   (Use `--infer-types' to enable type inference.)
 bug410.m:055: Inferred :- pred make_titles(pred(V_1, V_2, V_2), V_2, T3).
+bug410.m:055: Error: predicate `make_titles'/3 has no mode declaration.
+bug410.m:055:   (Use `--infer-modes' to enable mode inference.)
 bug410.m:055: Inferred :- mode make_titles(di(/* unique */(pred(out, in, out)
 bug410.m:055:   is det)), (ground >> not_reached), out(not_reached)).
 bug410.m:055: Inferred :- mode make_titles(di(/* unique */(pred(out, in, out)
diff --git a/tests/invalid_nodepend/constrained_poly_insts.err_exp b/tests/invalid_nodepend/constrained_poly_insts.err_exp
index 7b6816c4c..77a0e226c 100644
--- a/tests/invalid_nodepend/constrained_poly_insts.err_exp
+++ b/tests/invalid_nodepend/constrained_poly_insts.err_exp
@@ -12,13 +12,17 @@ constrained_poly_insts.m:020: Error: inconsistent constraints on inst variables
 constrained_poly_insts.m:020:   I and J in predicate declaration.
 constrained_poly_insts.m:029: Error: clause for predicate `q'/2 without a
 constrained_poly_insts.m:029:   corresponding `:- pred' declaration.
+constrained_poly_insts.m:029:   (Use `--infer-types' to enable type inference.)
 constrained_poly_insts.m:029: Inferred :- pred q(T1, T1).
+constrained_poly_insts.m:029: Error: predicate `q'/2 has no mode declaration.
+constrained_poly_insts.m:029:   (Use `--infer-modes' to enable mode inference.)
 constrained_poly_insts.m:031: Error: clause for function `s'/1 without a
 constrained_poly_insts.m:031:   corresponding `:- func' declaration.
 constrained_poly_insts.m:031: Inferred :- func s(T1) = T1.
 constrained_poly_insts.m:032: Error: clause for predicate `t'/4 without a
 constrained_poly_insts.m:032:   corresponding `:- pred' declaration.
 constrained_poly_insts.m:032: Inferred :- pred t(T1, T1, T3, T3).
+constrained_poly_insts.m:032: Error: predicate `t'/4 has no mode declaration.
 constrained_poly_insts.m:033: In clause for `u(in((I =< ground)), out((I =<
 constrained_poly_insts.m:033:   ground)))':
 constrained_poly_insts.m:033:   mode error: argument 2 became too instantiated.
diff --git a/tests/invalid_nodepend/invalid_binary_literal.err_exp b/tests/invalid_nodepend/invalid_binary_literal.err_exp
index 81d051273..04915df07 100644
--- a/tests/invalid_nodepend/invalid_binary_literal.err_exp
+++ b/tests/invalid_nodepend/invalid_binary_literal.err_exp
@@ -32,6 +32,7 @@ invalid_binary_literal.m:033: Syntax error: a binary literal cannot end with an
 invalid_binary_literal.m:033:   underscore.
 invalid_binary_literal.m:035: Error: clause for predicate `b11'/0 without a
 invalid_binary_literal.m:035:   corresponding `:- pred' declaration.
+invalid_binary_literal.m:035:   (Use `--infer-types' to enable type inference.)
 invalid_binary_literal.m:035: Inferred :- pred b11.
 invalid_binary_literal.m:035: Syntax error: a decimal literal cannot end with
 invalid_binary_literal.m:035:   an underscore.
diff --git a/tests/invalid_nodepend/invalid_float_literal.err_exp b/tests/invalid_nodepend/invalid_float_literal.err_exp
index f0acfdf23..0aafebf23 100644
--- a/tests/invalid_nodepend/invalid_float_literal.err_exp
+++ b/tests/invalid_nodepend/invalid_float_literal.err_exp
@@ -35,6 +35,7 @@ invalid_float_literal.m:039:   digits; it should not appear just before a
 invalid_float_literal.m:039:   decimal point.
 invalid_float_literal.m:041: Error: clause for predicate `-'/2 without a
 invalid_float_literal.m:041:   corresponding `:- pred' declaration.
+invalid_float_literal.m:041:   (Use `--infer-types' to enable type inference.)
 invalid_float_literal.m:041: Inferred :- pred '-'(T1, int).
 invalid_float_literal.m:041: Syntax error: unterminated exponent in float
 invalid_float_literal.m:041:   literal.
diff --git a/tests/invalid_nodepend/invalid_hex_literal.err_exp b/tests/invalid_nodepend/invalid_hex_literal.err_exp
index c546091e8..85136cd04 100644
--- a/tests/invalid_nodepend/invalid_hex_literal.err_exp
+++ b/tests/invalid_nodepend/invalid_hex_literal.err_exp
@@ -32,6 +32,7 @@ invalid_hex_literal.m:033: Syntax error: a hexadecimal literal cannot end with
 invalid_hex_literal.m:033:   an underscore.
 invalid_hex_literal.m:035: Error: clause for predicate `xff'/0 without a
 invalid_hex_literal.m:035:   corresponding `:- pred' declaration.
+invalid_hex_literal.m:035:   (Use `--infer-types' to enable type inference.)
 invalid_hex_literal.m:035: Inferred :- pred xff.
 invalid_hex_literal.m:035: Syntax error: a decimal literal cannot end with an
 invalid_hex_literal.m:035:   underscore.
diff --git a/tests/invalid_nodepend/invalid_octal_literal.err_exp b/tests/invalid_nodepend/invalid_octal_literal.err_exp
index dbba0157d..a0416dfce 100644
--- a/tests/invalid_nodepend/invalid_octal_literal.err_exp
+++ b/tests/invalid_nodepend/invalid_octal_literal.err_exp
@@ -28,6 +28,7 @@ invalid_octal_literal.m:033: Syntax error: an octal literal cannot end with an
 invalid_octal_literal.m:033:   underscore.
 invalid_octal_literal.m:035: Error: clause for predicate `o77'/0 without a
 invalid_octal_literal.m:035:   corresponding `:- pred' declaration.
+invalid_octal_literal.m:035:   (Use `--infer-types' to enable type inference.)
 invalid_octal_literal.m:035: Inferred :- pred o77.
 invalid_octal_literal.m:035: Syntax error: a decimal literal cannot end with an
 invalid_octal_literal.m:035:   underscore.
diff --git a/tests/invalid_nodepend/null_char.err_exp b/tests/invalid_nodepend/null_char.err_exp
index f1aeb9221..002f7a42e 100644
--- a/tests/invalid_nodepend/null_char.err_exp
+++ b/tests/invalid_nodepend/null_char.err_exp
@@ -1,5 +1,6 @@
 null_char.m:017: Error: clause for predicate `int'/0 without a corresponding
 null_char.m:017:   `:- pred' declaration.
+null_char.m:017:   (Use `--infer-types' to enable type inference.)
 null_char.m:017: Inferred :- pred int.
 null_char.m:017: Syntax error: the null character is illegal in strings and
 null_char.m:017:   names.
diff --git a/tests/invalid_nodepend/test_with_type.err_exp b/tests/invalid_nodepend/test_with_type.err_exp
index d0916d1dd..61f4a3cef 100644
--- a/tests/invalid_nodepend/test_with_type.err_exp
+++ b/tests/invalid_nodepend/test_with_type.err_exp
@@ -11,6 +11,7 @@ test_with_type.m:022:   error: expected the type after `with_type' to be a
 test_with_type.m:022:   higher order function type, but it is not.
 test_with_type.m:023: Error: `:- mode' declaration for function `with_type_2'/3
 test_with_type.m:023:   without a corresponding `:- func' declaration.
+test_with_type.m:023:   (Use `--infer-types' to enable type inference.)
 test_with_type.m:025: In the declaration of predicate `with_type_3':
 test_with_type.m:025:   error: the `with_type` and `with_inst` annotations are
 test_with_type.m:025:   incompatible, because they specify two types but three
diff --git a/tests/invalid_nodepend/typeclass_test_2.err_exp b/tests/invalid_nodepend/typeclass_test_2.err_exp
index 064f59813..67ad3d682 100644
--- a/tests/invalid_nodepend/typeclass_test_2.err_exp
+++ b/tests/invalid_nodepend/typeclass_test_2.err_exp
@@ -10,4 +10,5 @@ typeclass_test_2.m:023:   got
 typeclass_test_2.m:023:     ((type_num / 0) is foo_type_num).
 typeclass_test_2.m:026: Error: clause for function `foo_type_num'/1 without a
 typeclass_test_2.m:026:   corresponding `:- func' declaration.
+typeclass_test_2.m:026:   (Use `--infer-types' to enable type inference.)
 typeclass_test_2.m:026: Inferred :- func foo_type_num(T1) = int.
diff --git a/tests/invalid_nodepend/types.err_exp b/tests/invalid_nodepend/types.err_exp
index 2cb68daeb..45b253645 100644
--- a/tests/invalid_nodepend/types.err_exp
+++ b/tests/invalid_nodepend/types.err_exp
@@ -9,6 +9,7 @@ types.m:011: Error: the function symbol `f'/1 occur
 types.m:011:   definition of type constructor `t'/0.
 types.m:023: Error: clause for predicate `r'/0 without a corresponding
 types.m:023:   `:- pred' declaration.
+types.m:023:   (Use `--infer-types' to enable type inference.)
 types.m:026: Error: clause for predicate `a'/1 without a corresponding
 types.m:026:   `:- pred' declaration.
 types.m:053: Error: the type `t'/2 has this declaration, but it has no