From 89bbe43c61320d6415d2f530df54dc4f6ccf03d4 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= Date: Mon, 3 Feb 2014 12:24:34 +0100 Subject: dialyzer: Silence useless warnings about list comprehensions Dialyzer will warn if the value of list comprehension is ignored by putting it in a sequence like this: [SomeSideEffect(E) || E <- Es], ok To avoid a warning, you'll have to write: _ = [SomeSideEffect(E) || E <- Es], ok Most of the time, this warning is merely annoying because it does not point out any real errors. Kostis Sagonas suggested that by suppressing the warning for list comprehension that return a list of a simple type (e.g. ['ok']), there would be no warning for code such as: [io:format("~p\n", [E]) || E <- Es], ok but there would be still be a warning for: [file:close(Fd) || Fd <- Fds], ok because an error condition is ignored. --- lib/dialyzer/src/dialyzer_dataflow.erl | 14 +++- .../unmatched_returns_SUITE_data/dialyzer_options | 1 + .../results/lc_warnings | 5 ++ .../src/lc_warnings/lc_warnings.erl | 95 ++++++++++++++++++++++ .../src/lc_warnings/opaque_atom_adt.erl | 9 ++ 5 files changed, 122 insertions(+), 2 deletions(-) create mode 100644 lib/dialyzer/test/unmatched_returns_SUITE_data/dialyzer_options create mode 100644 lib/dialyzer/test/unmatched_returns_SUITE_data/results/lc_warnings create mode 100644 lib/dialyzer/test/unmatched_returns_SUITE_data/src/lc_warnings/lc_warnings.erl create mode 100644 lib/dialyzer/test/unmatched_returns_SUITE_data/src/lc_warnings/opaque_atom_adt.erl diff --git a/lib/dialyzer/src/dialyzer_dataflow.erl b/lib/dialyzer/src/dialyzer_dataflow.erl index 33fa107019..288d2dfbeb 100644 --- a/lib/dialyzer/src/dialyzer_dataflow.erl +++ b/lib/dialyzer/src/dialyzer_dataflow.erl @@ -58,10 +58,12 @@ t_fun_range/2, t_integer/0, t_integers/1, t_is_any/1, t_is_atom/1, t_is_atom/2, t_is_any_atom/3, t_is_boolean/2, - t_is_integer/2, t_is_nil/2, t_is_none/1, t_is_none_or_unit/1, + t_is_integer/2, t_is_list/1, + t_is_nil/2, t_is_none/1, t_is_none_or_unit/1, t_is_number/2, t_is_reference/2, t_is_pid/2, t_is_port/2, t_is_unit/1, - t_limit/2, t_list/0, t_maybe_improper_list/0, t_module/0, + t_limit/2, t_list/0, t_list_elements/2, + t_maybe_improper_list/0, t_module/0, t_none/0, t_non_neg_integer/0, t_number/0, t_number_vals/2, t_pid/0, t_port/0, t_product/1, t_reference/0, t_to_string/2, t_to_tlist/1, @@ -293,6 +295,7 @@ traverse(Tree, Map, State) -> t_is_any(ArgType) orelse t_is_simple(ArgType, State) orelse is_call_to_send(Arg) + orelse is_lc_simple_list(Arg, ArgType, State) of true -> % do not warn in these cases State1; @@ -2710,6 +2713,13 @@ is_call_to_send(Tree) -> andalso (Arity =:= 2) end. +is_lc_simple_list(Tree, TreeType, State) -> + Opaques = State#state.opaques, + Ann = cerl:get_ann(Tree), + lists:member(list_comprehension, Ann) + andalso t_is_list(TreeType) + andalso t_is_simple(t_list_elements(TreeType, Opaques), State). + filter_match_fail([Clause] = Cls) -> Body = cerl:clause_body(Clause), case cerl:type(Body) of diff --git a/lib/dialyzer/test/unmatched_returns_SUITE_data/dialyzer_options b/lib/dialyzer/test/unmatched_returns_SUITE_data/dialyzer_options new file mode 100644 index 0000000000..49ac917f61 --- /dev/null +++ b/lib/dialyzer/test/unmatched_returns_SUITE_data/dialyzer_options @@ -0,0 +1 @@ +{dialyzer_options, [{warnings, [unmatched_returns]}]}. diff --git a/lib/dialyzer/test/unmatched_returns_SUITE_data/results/lc_warnings b/lib/dialyzer/test/unmatched_returns_SUITE_data/results/lc_warnings new file mode 100644 index 0000000000..2784f2119e --- /dev/null +++ b/lib/dialyzer/test/unmatched_returns_SUITE_data/results/lc_warnings @@ -0,0 +1,5 @@ + +lc_warnings.erl:32: Expression produces a value of type [opaque_atom_adt:opaque_atom()], but this value is unmatched +lc_warnings.erl:43: Expression produces a value of type [array()], but this value is unmatched +lc_warnings.erl:65: Expression produces a value of type [lc_warnings:opaque_tuple()], but this value is unmatched +lc_warnings.erl:7: Expression produces a value of type ['ok' | {'error',atom()}], but this value is unmatched diff --git a/lib/dialyzer/test/unmatched_returns_SUITE_data/src/lc_warnings/lc_warnings.erl b/lib/dialyzer/test/unmatched_returns_SUITE_data/src/lc_warnings/lc_warnings.erl new file mode 100644 index 0000000000..cb01a8fde3 --- /dev/null +++ b/lib/dialyzer/test/unmatched_returns_SUITE_data/src/lc_warnings/lc_warnings.erl @@ -0,0 +1,95 @@ +-module(lc_warnings). +-compile([export_all]). + +close(Fs) -> + %% There should be a warning since we ignore a potential + %% {error,Error} return from file:close/1. + [file:close(F) || F <- Fs], + + %% No warning because the type of unmatched return will be ['ok'] + %% (which is a list of a simple type). + [ok = file:close(F) || F <- Fs], + + %% Suppressed. + _ = [file:close(F) || F <- Fs], + ok. + +format(X) -> + %% No warning since the result of the list comprehension is + %% a list of simple. + [io:format("~p\n", [E]) || E <- X], + + %% Warning explicitly suppressed. + _ = [io:format("~p\n", [E]) || E <- X], + ok. + +opaque1() -> + List = gen_atom(), + %% This is a list of an externally defined opaque type. Since + %% we are not allowed to peek inside opaque types, there should + %% be a warning (even though the type in this case happens to be + %% an atom). + [E || E <- List], + + %% Suppressed. + _ = [E || E <- List], + ok. + +opaque2() -> + List = gen_array(), + %% This is an list of an externally defined opaque type. Since + %% we are not allowed to peek inside opaque types, there should + %% be a warning. + [E || E <- List], + + %% Suppressed. + _ = [E || E <- List], + ok. + +opaque3() -> + List = gen_int(), + + %% No warning, since we are allowed to look into the type and can + %% see that it is a simple type. + [E || E <- List], + + %% Suppressed. + _ = [E || E <- List], + ok. + +opaque4() -> + List = gen_tuple(), + + %% There should be a warning, since we are allowed to look inside + %% the opaque type and see that it is a tuple (non-simple). + [E || E <- List], + + %% Suppressed. + _ = [E || E <- List], + ok. + +gen_atom() -> + [opaque_atom_adt:atom(ok)]. + +gen_array() -> + [array:new()]. + + +gen_int() -> + [opaque_int(42)]. + +gen_tuple() -> + [opaque_tuple(x, 25)]. + +-opaque opaque_int() :: integer(). + +-spec opaque_int(integer()) -> opaque_int(). + +opaque_int(Int) -> Int. + +-opaque opaque_tuple() :: {any(),any()}. + +-spec opaque_tuple(any(), any()) -> opaque_tuple(). + +opaque_tuple(X, Y) -> + {X,Y}. diff --git a/lib/dialyzer/test/unmatched_returns_SUITE_data/src/lc_warnings/opaque_atom_adt.erl b/lib/dialyzer/test/unmatched_returns_SUITE_data/src/lc_warnings/opaque_atom_adt.erl new file mode 100644 index 0000000000..b5b51fe75b --- /dev/null +++ b/lib/dialyzer/test/unmatched_returns_SUITE_data/src/lc_warnings/opaque_atom_adt.erl @@ -0,0 +1,9 @@ +-module(opaque_atom_adt). +-export([atom/1]). + +-opaque opaque_atom() :: atom(). + +-spec atom(atom()) -> opaque_atom(). + +atom(Atom) -> + Atom. -- cgit v1.2.3