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authorBjörn Gustavsson <[email protected]>2014-02-05 14:01:00 +0100
committerBjörn Gustavsson <[email protected]>2014-02-05 14:01:00 +0100
commit1375078619eb547eecdd5e0e155c00c39dd2d493 (patch)
tree949892e4e1f1d4d65a6dd9b3ccb408812492c7ab /lib
parent8d71ab498974b5f0623eac50c4f94f62fc229a94 (diff)
parent4aeef6279f19a15c728befe817d78d669bb5d1fd (diff)
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Merge branch 'bjorn/eep37/OTP-11537'
* bjorn/eep37/OTP-11537: Issue a warning when a named fun is constructed but not used
Diffstat (limited to 'lib')
-rw-r--r--lib/compiler/src/sys_core_fold.erl4
-rw-r--r--lib/compiler/src/v3_core.erl3
-rw-r--r--lib/compiler/test/warnings_SUITE.erl9
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 d1eec9e347..9ce6bb48bf 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.