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authorStavros Aronis <[email protected]>2016-06-08 13:13:04 +0200
committerStavros Aronis <[email protected]>2016-06-08 13:13:04 +0200
commitb13412d2e4331fa426a6722a04310cbcbf1731d6 (patch)
tree17fba1d7099d652eeab812b4b1a72e44cc9277bd /lib/dialyzer/src
parentd26c15e07229c90ba8353bd78d5406ada0f13271 (diff)
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Fix a bug in Dialyzer related to call-site analysis
Dialyzer's "dataflow" module is using information from the callgraph to determine which functions may be called at a particular call-site. Unfortunately this information can include functions that are certainly not among the possible choices. We don't want to emit warnings in such cases, so a "reasonable" compromise is to stay silent if there are many possible funs and at least one of them can succeed. Bug reported by Dan Gudmundsson, test shrunk down by Magnus Lång.
Diffstat (limited to 'lib/dialyzer/src')
-rw-r--r--lib/dialyzer/src/dialyzer_dataflow.erl58
1 files changed, 50 insertions, 8 deletions
diff --git a/lib/dialyzer/src/dialyzer_dataflow.erl b/lib/dialyzer/src/dialyzer_dataflow.erl
index 5ab0c39c04..3349b12932 100644
--- a/lib/dialyzer/src/dialyzer_dataflow.erl
+++ b/lib/dialyzer/src/dialyzer_dataflow.erl
@@ -430,17 +430,35 @@ handle_apply(Tree, Map, State) ->
handle_apply_or_call(FunInfoList, Args, ArgTypes, Map, Tree, State) ->
None = t_none(),
+ %% Call-site analysis may be inaccurate and consider more funs than those that
+ %% are actually possible. If all of them are incorrect, then warnings can be
+ %% emitted. If at least one fun is ok, however, then no warning is emitted,
+ %% just in case the bad ones are not really possible. The last argument is
+ %% used for this, with the following encoding:
+ %% Initial value: {none, []}
+ %% First fun checked: {one, <List of warns>}
+ %% More funs checked: {many, <List of warns>}
+ %% A '{one, []}' can only become '{many, []}'.
+ %% If at any point an fun does not add warnings, then the list is also
+ %% replaced with an empty list.
handle_apply_or_call(FunInfoList, Args, ArgTypes, Map, Tree, State,
- [None || _ <- ArgTypes], None, false).
+ [None || _ <- ArgTypes], None, false, {none, []}).
handle_apply_or_call([{local, external}|Left], Args, ArgTypes, Map, Tree, State,
- _AccArgTypes, _AccRet, _HadExternal) ->
+ _AccArgTypes, _AccRet, _HadExternal, Warns) ->
+ {HowMany, _} = Warns,
+ NewHowMany =
+ case HowMany of
+ none -> one;
+ _ -> many
+ end,
+ NewWarns = {NewHowMany, []},
handle_apply_or_call(Left, Args, ArgTypes, Map, Tree, State,
- ArgTypes, t_any(), true);
+ ArgTypes, t_any(), true, NewWarns);
handle_apply_or_call([{TypeOfApply, {Fun, Sig, Contr, LocalRet}}|Left],
Args, ArgTypes, Map, Tree,
#state{opaques = Opaques} = State,
- AccArgTypes, AccRet, HadExternal) ->
+ AccArgTypes, AccRet, HadExternal, Warns) ->
Any = t_any(),
AnyArgs = [Any || _ <- Args],
GenSig = {AnyArgs, fun(_) -> t_any() end},
@@ -586,16 +604,32 @@ handle_apply_or_call([{TypeOfApply, {Fun, Sig, Contr, LocalRet}}|Left],
end,
NewAccRet = t_sup(AccRet, TotalRet),
?debug("NewAccRet: ~s\n", [t_to_string(NewAccRet)]),
+ {NewWarnings, State4} = state__remove_added_warnings(State, State3),
+ {HowMany, OldWarnings} = Warns,
+ NewWarns =
+ case HowMany of
+ none -> {one, NewWarnings};
+ _ ->
+ case OldWarnings =:= [] of
+ true -> {many, []};
+ false ->
+ case NewWarnings =:= [] of
+ true -> {many, []};
+ false -> {many, NewWarnings ++ OldWarnings}
+ end
+ end
+ end,
handle_apply_or_call(Left, Args, ArgTypes, Map, Tree,
- State3, NewAccArgTypes, NewAccRet, HadExternal);
+ State4, NewAccArgTypes, NewAccRet, HadExternal, NewWarns);
handle_apply_or_call([], Args, _ArgTypes, Map, _Tree, State,
- AccArgTypes, AccRet, HadExternal) ->
+ AccArgTypes, AccRet, HadExternal, {_, Warnings}) ->
+ State1 = state__add_warnings(Warnings, State),
case HadExternal of
false ->
NewMap = enter_type_lists(Args, AccArgTypes, Map),
- {State, NewMap, AccRet};
+ {State1, NewMap, AccRet};
true ->
- {had_external, State}
+ {had_external, State1}
end.
apply_fail_reason(FailedSig, FailedBif, FailedContract) ->
@@ -3038,6 +3072,14 @@ state__add_warning(#state{warnings = Warnings, warning_mode = true} = State,
end
end.
+state__remove_added_warnings(OldState, NewState) ->
+ #state{warnings = OldWarnings} = OldState,
+ #state{warnings = NewWarnings} = NewState,
+ {NewWarnings -- OldWarnings, NewState#state{warnings = OldWarnings}}.
+
+state__add_warnings(Warns, #state{warnings = Warnings} = State) ->
+ State#state{warnings = Warns ++ Warnings}.
+
-spec state__set_curr_fun(curr_fun(), state()) -> state().
state__set_curr_fun(undefined, State) ->