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| author | Björn Gustavsson <[email protected]> | 2014-01-30 15:34:47 +0100 |
|---|---|---|
| committer | Björn Gustavsson <[email protected]> | 2014-01-30 15:44:27 +0100 |
| commit | 4aeef6279f19a15c728befe817d78d669bb5d1fd (patch) | |
| tree | d9046d545bc2a62e0cf523e7a64f5860a2387029 | |
| parent | fdcdaca338849d7f63d4300e489318f6ee275d82 (diff) | |
| download | otp-4aeef6279f19a15c728befe817d78d669bb5d1fd.tar.gz otp-4aeef6279f19a15c728befe817d78d669bb5d1fd.tar.bz2 otp-4aeef6279f19a15c728befe817d78d669bb5d1fd.zip | |
Issue a warning when a named fun is constructed but not used
| -rw-r--r-- | lib/compiler/src/sys_core_fold.erl | 4 | ||||
| -rw-r--r-- | lib/compiler/src/v3_core.erl | 3 | ||||
| -rw-r--r-- | lib/compiler/test/warnings_SUITE.erl | 9 |
3 files changed, 13 insertions, 3 deletions
diff --git a/lib/compiler/src/sys_core_fold.erl b/lib/compiler/src/sys_core_fold.erl index 1cdbac5693..40f324b839 100644 --- a/lib/compiler/src/sys_core_fold.erl +++ b/lib/compiler/src/sys_core_fold.erl @@ -305,6 +305,10 @@ expr(#c_let{}=Let, Ctxt, Sub) -> %% Now recursively re-process the new expression. expr(Expr, Ctxt, sub_new_preserve_types(Sub)) end; +expr(#c_letrec{body=#c_var{}}=Letrec, effect, _Sub) -> + %% This is named fun in an 'effect' context. Warn and ignore. + add_warning(Letrec, useless_building), + void(); expr(#c_letrec{defs=Fs0,body=B0}=Letrec, Ctxt, Sub) -> Fs1 = map(fun ({Name,Fb}) -> {Name,expr(Fb, {letrec,Ctxt}, Sub)} diff --git a/lib/compiler/src/v3_core.erl b/lib/compiler/src/v3_core.erl index e30bfa729c..59863f52ec 100644 --- a/lib/compiler/src/v3_core.erl +++ b/lib/compiler/src/v3_core.erl @@ -2088,7 +2088,8 @@ cexpr(#ifun{anno=#a{us=Us0}=A0,name={named,Name},fc=#iclause{pats=Ps}}=Fun0, RecVar = #c_var{name={Name,length(Ps)}}, Let = #c_let{vars=[#c_var{name=Name}],arg=RecVar,body=Body}, CFun1 = CFun0#c_fun{body=Let}, - Letrec = #c_letrec{defs=[{RecVar,CFun1}], + Letrec = #c_letrec{anno=A0#a.anno, + defs=[{RecVar,CFun1}], body=RecVar}, {Letrec,[],Us1,St1} end; diff --git a/lib/compiler/test/warnings_SUITE.erl b/lib/compiler/test/warnings_SUITE.erl index 7186956603..16d15a59e5 100644 --- a/lib/compiler/test/warnings_SUITE.erl +++ b/lib/compiler/test/warnings_SUITE.erl @@ -390,6 +390,10 @@ effect(Config) when is_list(Config) -> <<X:8>>; unused_fun -> fun() -> {ok,X} end; + unused_named_fun -> + fun F(0) -> 1; + F(N) -> N*F(N-1) + end; unused_atom -> ignore; %no warning unused_nil -> @@ -484,8 +488,9 @@ effect(Config) when is_list(Config) -> {22,sys_core_fold,{no_effect,{erlang,is_integer,1}}}, {24,sys_core_fold,useless_building}, {26,sys_core_fold,useless_building}, - {32,sys_core_fold,{no_effect,{erlang,'=:=',2}}}, - {34,sys_core_fold,{no_effect,{erlang,get_cookie,0}}}]}}], + {28,sys_core_fold,useless_building}, + {36,sys_core_fold,{no_effect,{erlang,'=:=',2}}}, + {38,sys_core_fold,{no_effect,{erlang,get_cookie,0}}}]}}], ?line [] = run(Config, Ts), ok. |