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| author | Hans Bolinder <[email protected]> | 2018-08-27 13:14:29 +0200 |
|---|---|---|
| committer | Hans Bolinder <[email protected]> | 2018-08-28 08:27:52 +0200 |
| commit | fd9b5ae4193fbab66093c88728c0dbeaa3b57312 (patch) | |
| tree | fd3f8b46afb4b5745f0f9a02b2498cad7826bedc /lib/dialyzer | |
| parent | 00401985f1c9227b6e94309ae5526c2ebf341527 (diff) | |
| download | otp-fd9b5ae4193fbab66093c88728c0dbeaa3b57312.tar.gz otp-fd9b5ae4193fbab66093c88728c0dbeaa3b57312.tar.bz2 otp-fd9b5ae4193fbab66093c88728c0dbeaa3b57312.zip | |
dialyzer: Improve handling of complex guards
See also https://bugs.erlang.org/browse/ERL-680.
The right associative short circuit expressions 'andalso' and 'orelse'
are expanded by the Compiler (see v3_core) into 'case' expressions. If
parentheses are used to enforce left associativeness, variables are
introduced, and the time needed by Dialyzer increases exponentially.
Rather than trying to fix Dialyzer itself, v3_core now rewrites
repeated use of 'andalso' ('orelse') into right associative
expressions before creating the 'case' expressions.
Diffstat (limited to 'lib/dialyzer')
| -rw-r--r-- | lib/dialyzer/test/small_SUITE_data/results/left_assoc | 2 | ||||
| -rw-r--r-- | lib/dialyzer/test/small_SUITE_data/src/left_assoc.erl | 96 |
2 files changed, 98 insertions, 0 deletions
diff --git a/lib/dialyzer/test/small_SUITE_data/results/left_assoc b/lib/dialyzer/test/small_SUITE_data/results/left_assoc new file mode 100644 index 0000000000..58cdad29de --- /dev/null +++ b/lib/dialyzer/test/small_SUITE_data/results/left_assoc @@ -0,0 +1,2 @@ + +left_assoc.erl:93: The variable __@2 can never match since previous clauses completely covered the type binary() diff --git a/lib/dialyzer/test/small_SUITE_data/src/left_assoc.erl b/lib/dialyzer/test/small_SUITE_data/src/left_assoc.erl new file mode 100644 index 0000000000..0250e4ab49 --- /dev/null +++ b/lib/dialyzer/test/small_SUITE_data/src/left_assoc.erl @@ -0,0 +1,96 @@ +-module(left_assoc). + +%% As pointed out in ERL-680, analyzing guards with short circuit +%% operators becomes very slow as the number of left associations +%% grows. + +-spec from_iso8601('Elixir.String':t(), 'Elixir.Calendar':calendar()) -> + {ok, t()} | {error, atom()}. + +-export_type([t/0]). + +-type t() :: + #{'__struct__' := 'Elixir.Date', + calendar := 'Elixir.Calendar':calendar(), + day := 'Elixir.Calendar':day(), + month := 'Elixir.Calendar':month(), + year := 'Elixir.Calendar':year()}. + +-export([from_iso8601/1, + from_iso8601/2]). + +from_iso8601(__@1) -> + from_iso8601(__@1, 'Elixir.Calendar.ISO'). + +from_iso8601(<<45/integer,_rest@1/binary>>, _calendar@1) -> + case raw_from_iso8601(_rest@1, _calendar@1) of + {ok,#{year := _year@1} = _date@1} -> + {ok,_date@1#{year := - _year@1}}; + __@1 -> + __@1 + end; +from_iso8601(<<_rest@1/binary>>, _calendar@1) -> + raw_from_iso8601(_rest@1, _calendar@1). + +raw_from_iso8601(_string@1, _calendar@1) -> + case _string@1 of + <<_y1@1/integer, + _y2@1/integer, + _y3@1/integer, + _y4@1/integer, + 45/integer, + _m1@1/integer, + _m2@1/integer, + 45/integer, + _d1@1/integer, + _d2@1/integer>> + when + ((((((((((((((_y1@1 >= 48 + andalso + _y1@1 =< 57) + andalso + _y2@1 >= 48) + andalso + _y2@1 =< 57) + andalso + _y3@1 >= 48) + andalso + _y3@1 =< 57) + andalso + _y4@1 >= 48) + andalso + _y4@1 =< 57) + andalso + _m1@1 >= 48) + andalso + _m1@1 =< 57) + andalso + _m2@1 >= 48) + andalso + _m2@1 =< 57) + andalso + _d1@1 >= 48) + andalso + _d1@1 =< 57) + andalso + _d2@1 >= 48) + andalso + _d2@1 =< 57 -> + {ok, + #{year => (_y1@1 - 48) * 1000 + (_y2@1 - 48) * 100 + + + (_y3@1 - 48) * 10 + + + (_y4@1 - 48), + month => (_m1@1 - 48) * 10 + (_m2@1 - 48), + day => (_d1@1 - 48) * 10 + (_d2@1 - 48), + calendar => _calendar@1, + '__struct__' => 'Elixir.Date'}}; + __@1 -> + case __@1 of + _ -> + {error,invalid_format}; + __@2 -> + error({with_clause,__@2}) + end + end. |