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-rw-r--r--lib/compiler/src/sys_core_fold.erl14
1 files changed, 14 insertions, 0 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl
index 2618f7adba..ea1959d0f8 100644
--- a/lib/compiler/src/sys_core_fold.erl
+++ b/lib/compiler/src/sys_core_fold.erl
@@ -1603,6 +1603,7 @@ eval_case(#c_case{arg=E,clauses=[#c_clause{pats=Ps0,
%% is correct, the clause will always match at run-time.
Case;
{true,Bs} ->
+ eval_case_warn(B),
{Ps,As} = unzip(Bs),
InnerLet = cerl:c_let(Ps, core_lib:make_values(As), B),
Let = cerl:c_let(Vs, E, InnerLet),
@@ -1610,6 +1611,19 @@ eval_case(#c_case{arg=E,clauses=[#c_clause{pats=Ps0,
end;
eval_case(Case, _) -> Case.
+eval_case_warn(#c_primop{anno=Anno,
+ name=#c_literal{val=match_fail},
+ args=[#c_literal{val=Reason}]}=Core)
+ when is_atom(Reason) ->
+ case member(eval_failure, Anno) of
+ false ->
+ ok;
+ true ->
+ %% Example: M = not_map, M#{k:=v}
+ add_warning(Core, {eval_failure,Reason})
+ end;
+eval_case_warn(_) -> ok.
+
%% case_opt(CaseArg, [Clause]) -> {CaseArg,[Clause]}.
%% Try and optimise a case by avoid building tuples or lists
%% in the case expression. Instead combine the variable parts