diff options
Diffstat (limited to 'lib/compiler/test/beam_type_SUITE.erl')
| -rw-r--r-- | lib/compiler/test/beam_type_SUITE.erl | 41 |
1 files changed, 39 insertions, 2 deletions
diff --git a/lib/compiler/test/beam_type_SUITE.erl b/lib/compiler/test/beam_type_SUITE.erl index 5189afde58..65e4e59be9 100644 --- a/lib/compiler/test/beam_type_SUITE.erl +++ b/lib/compiler/test/beam_type_SUITE.erl @@ -25,7 +25,7 @@ cons/1,tuple/1,record_float/1,binary_float/1,float_compare/1, arity_checks/1,elixir_binaries/1,find_best/1, test_size/1,cover_lists_functions/1,list_append/1,bad_binary_unit/1, - none_argument/1,success_type_oscillation/1]). + none_argument/1,success_type_oscillation/1,type_subtraction/1]). suite() -> [{ct_hooks,[ts_install_cth]}]. @@ -52,7 +52,8 @@ groups() -> list_append, bad_binary_unit, none_argument, - success_type_oscillation + success_type_oscillation, + type_subtraction ]}]. init_per_suite(Config) -> @@ -596,5 +597,41 @@ sto_1(case_4_1) -> {b, [sto_1(case_3_1)]}; sto_1(case_4_2) -> {b, [sto_1(case_3_2)]}; sto_1(step_4_3) -> {b, [sto_1(case_3_3)]}. +%% ERL-1440: On inequality, we subtracted the type *common to* both variables +%% rather than the left-hand type from the right-hand variable and vice versa, +%% giving an erroneously narrow type. +%% +%% In the test below, we have functions returning integers ranged 1..2 and +%% 2..3 and test for their equality. We know that it can only succeed when both +%% return 2, but they can fail when the former returns 1 or the latter returns +%% 3, so we must not subtract 2 on the failure path. +type_subtraction(Config) when is_list(Config) -> + true = type_subtraction_1(id(<<"A">>)), + ok. + +type_subtraction_1(_x@1) -> + _a@1 = ts_12(_x@1), + _b@1 = ts_23(_x@1), + case _a@1 /= _b@1 of + false -> error; + true -> _a@1 =:= 3 andalso _b@1 =:= 2 + end. + +ts_12(_x@1) -> + case _x@1 == <<"A">> of + false -> + 2; + true -> + 3 + end. + +ts_23(_x@1) -> + case _x@1 == <<"A">> of + false -> + 1; + true -> + 2 + end. + id(I) -> I. |