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-rw-r--r--lib/dialyzer/src/dialyzer_dataflow.erl44
-rw-r--r--lib/dialyzer/test/small_SUITE_data/results/unused_funs5
-rw-r--r--lib/dialyzer/test/small_SUITE_data/src/unused_funs.erl21
3 files changed, 60 insertions, 10 deletions
diff --git a/lib/dialyzer/src/dialyzer_dataflow.erl b/lib/dialyzer/src/dialyzer_dataflow.erl
index c5f93a3392..45b4abb253 100644
--- a/lib/dialyzer/src/dialyzer_dataflow.erl
+++ b/lib/dialyzer/src/dialyzer_dataflow.erl
@@ -102,6 +102,8 @@
| 'undefined', % race
fun_homes :: dict:dict(label(), mfa())
| 'undefined', % race
+ reachable_funs :: sets:set(label())
+ | 'undefined', % race
plt :: dialyzer_plt:plt()
| 'undefined', % race
opaques :: [type()]
@@ -269,9 +271,11 @@ traverse(Tree, Map, State) ->
case state__warning_mode(State) of
true -> {State, Map, Type};
false ->
- State2 = state__add_work(get_label(Tree), State),
+ FunLbl = get_label(Tree),
+ State2 = state__add_work(FunLbl, State),
State3 = state__update_fun_env(Tree, Map, State2),
- {State3, Map, Type}
+ State4 = state__add_reachable(FunLbl, State3),
+ {State4, Map, Type}
end;
'let' ->
handle_let(Tree, Map, State);
@@ -3039,25 +3043,35 @@ state__new(Callgraph, Codeserver, Tree, Plt, Module, Records) ->
{TreeMap, FunHomes} = build_tree_map(Tree, Callgraph),
Funs = dict:fetch_keys(TreeMap),
FunTab = init_fun_tab(Funs, dict:new(), TreeMap, Callgraph, Plt),
- ExportedFuns =
- [Fun || Fun <- Funs--[top], dialyzer_callgraph:is_escaping(Fun, Callgraph)],
- Work = init_work(ExportedFuns),
+ ExportedFunctions =
+ [Fun ||
+ Fun <- Funs--[top],
+ dialyzer_callgraph:is_escaping(Fun, Callgraph),
+ dialyzer_callgraph:lookup_name(Fun, Callgraph) =/= error
+ ],
+ Work = init_work(ExportedFunctions),
Env = lists:foldl(fun(Fun, Env) -> dict:store(Fun, map__new(), Env) end,
dict:new(), Funs),
#state{callgraph = Callgraph, codeserver = Codeserver,
envs = Env, fun_tab = FunTab, fun_homes = FunHomes, opaques = Opaques,
plt = Plt, races = dialyzer_races:new(), records = Records,
warning_mode = false, warnings = [], work = Work, tree_map = TreeMap,
- module = Module}.
+ module = Module, reachable_funs = sets:new()}.
state__warning_mode(#state{warning_mode = WM}) ->
WM.
state__set_warning_mode(#state{tree_map = TreeMap, fun_tab = FunTab,
- races = Races} = State) ->
+ races = Races, callgraph = Callgraph,
+ reachable_funs = ReachableFuns} = State) ->
?debug("==========\nStarting warning pass\n==========\n", []),
Funs = dict:fetch_keys(TreeMap),
- State#state{work = init_work([top|Funs--[top]]),
+ Work =
+ [Fun ||
+ Fun <- Funs--[top],
+ dialyzer_callgraph:lookup_name(Fun, Callgraph) =/= error orelse
+ sets:is_element(Fun, ReachableFuns)],
+ State#state{work = init_work(Work),
fun_tab = FunTab, warning_mode = true,
races = dialyzer_races:put_race_analysis(true, Races)}.
@@ -3149,7 +3163,8 @@ state__get_race_warnings(#state{races = Races} = State) ->
State1#state{races = Races1}.
state__get_warnings(#state{tree_map = TreeMap, fun_tab = FunTab,
- callgraph = Callgraph, plt = Plt} = State) ->
+ callgraph = Callgraph, plt = Plt,
+ reachable_funs = ReachableFuns} = State) ->
FoldFun =
fun({top, _}, AccState) -> AccState;
({FunLbl, Fun}, AccState) ->
@@ -3184,7 +3199,12 @@ state__get_warnings(#state{tree_map = TreeMap, fun_tab = FunTab,
GenRet = dialyzer_contracts:get_contract_return(C),
not t_is_unit(GenRet)
end,
- case Warn of
+ %% Do not output warnings for unreachable funs.
+ case
+ Warn andalso
+ (dialyzer_callgraph:lookup_name(FunLbl, Callgraph) =/= error
+ orelse sets:is_element(FunLbl, ReachableFuns))
+ of
true ->
case classify_returns(Fun) of
no_match ->
@@ -3255,6 +3275,10 @@ state__get_args_and_status(Tree, #state{fun_tab = FunTab}) ->
{ok, {ArgTypes, _}} -> {ArgTypes, true}
end.
+state__add_reachable(FunLbl, #state{reachable_funs = ReachableFuns}=State) ->
+ NewReachableFuns = sets:add_element(FunLbl, ReachableFuns),
+ State#state{reachable_funs = NewReachableFuns}.
+
build_tree_map(Tree, Callgraph) ->
Fun =
fun(T, {Dict, Homes, FunLbls} = Acc) ->
diff --git a/lib/dialyzer/test/small_SUITE_data/results/unused_funs b/lib/dialyzer/test/small_SUITE_data/results/unused_funs
new file mode 100644
index 0000000000..c468457ead
--- /dev/null
+++ b/lib/dialyzer/test/small_SUITE_data/results/unused_funs
@@ -0,0 +1,5 @@
+
+unused_funs.erl:10: The pattern 'error' can never match the type 'other_error'
+unused_funs.erl:15: Function not_used/0 will never be called
+unused_funs.erl:19: Function foo/1 will never be called
+unused_funs.erl:7: Function test/0 has no local return
diff --git a/lib/dialyzer/test/small_SUITE_data/src/unused_funs.erl b/lib/dialyzer/test/small_SUITE_data/src/unused_funs.erl
new file mode 100644
index 0000000000..c24cf3ea81
--- /dev/null
+++ b/lib/dialyzer/test/small_SUITE_data/src/unused_funs.erl
@@ -0,0 +1,21 @@
+%% See also ERL-593.
+
+-module(unused_funs).
+
+-export([test/0]).
+
+test() -> % "has no local return"
+ Var = outer_scope,
+ case other_error of
+ error -> % "can never match"
+ %% No warnings "no local return" and "_ = 1 can never match 0" (!)
+ foo(fun() -> {Var, 1 = 0} end)
+ end.
+
+not_used() -> % "will never be called"
+ %% No warnings "no local return" and "1 can never match 0".
+ foo(fun() -> 1 = 0 end).
+
+foo(Fun) -> % "will never be called"
+ 1 = 0, % No pattern match warning (foo/1 is not traversed at all).
+ Fun().