diff options
| -rw-r--r-- | lib/compiler/src/sys_core_fold.erl | 15 | ||||
| -rw-r--r-- | lib/compiler/test/warnings_SUITE.erl | 10 |
2 files changed, 22 insertions, 3 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl index c870bb68c8..9360556e00 100644 --- a/lib/compiler/src/sys_core_fold.erl +++ b/lib/compiler/src/sys_core_fold.erl @@ -1969,13 +1969,22 @@ case_tuple_pat([#c_tuple{es=Ps}], Arity) when length(Ps) =:= Arity -> case_tuple_pat([#c_literal{val=T}], Arity) when tuple_size(T) =:= Arity -> Ps = [#c_literal{val=E} || E <- tuple_to_list(T)], {ok,Ps,[]}; -case_tuple_pat([#c_var{anno=Anno}=V], Arity) -> - Vars = make_vars(Anno, 1, Arity), +case_tuple_pat([#c_var{anno=Anno0}=V], Arity) -> + Vars = make_vars(Anno0, 1, Arity), + + %% If the entire case statement is evaluated in an effect + %% context (e.g. "case {A,B} of ... end, ok"), there will + %% be a warning that a term is constructed but never used. + %% To avoid that warning, we must annotate the tuple as + %% compiler generated. + + Anno = [compiler_generated|Anno0], {ok,Vars,[{V,#c_tuple{anno=Anno,es=Vars}}]}; case_tuple_pat([#c_alias{var=V,pat=P}], Arity) -> case case_tuple_pat([P], Arity) of {ok,Ps,Avs} -> - Anno = core_lib:get_anno(P), + Anno0 = core_lib:get_anno(P), + Anno = [compiler_generated|Anno0], {ok,Ps,[{V,#c_tuple{anno=Anno,es=unalias_pat_list(Ps)}}|Avs]}; error -> error diff --git a/lib/compiler/test/warnings_SUITE.erl b/lib/compiler/test/warnings_SUITE.erl index 8cc3ca4199..dd18a6e1a3 100644 --- a/lib/compiler/test/warnings_SUITE.erl +++ b/lib/compiler/test/warnings_SUITE.erl @@ -453,6 +453,16 @@ effect(Config) when is_list(Config) -> true -> ok end, ok. + + m8(A, B) -> + case {A,B} of + V -> V + end, + ok. + + m9(Bs) -> + [{B,ok} = {B,foo:bar(B)} || B <- Bs], + ok. ">>, [], {warnings,[{5,sys_core_fold,{no_effect,{erlang,is_integer,1}}}, |