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-rw-r--r--erts/emulator/test/num_bif_SUITE.erl39
1 files changed, 37 insertions, 2 deletions
diff --git a/erts/emulator/test/num_bif_SUITE.erl b/erts/emulator/test/num_bif_SUITE.erl
index d950179882..f15217814a 100644
--- a/erts/emulator/test/num_bif_SUITE.erl
+++ b/erts/emulator/test/num_bif_SUITE.erl
@@ -1,7 +1,7 @@
%%
%% %CopyrightBegin%
%%
-%% Copyright Ericsson AB 1997-2017. All Rights Reserved.
+%% Copyright Ericsson AB 1997-2018. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
@@ -146,7 +146,7 @@ t_float_to_string(Config) when is_list(Config) ->
123456789012345678.0, [{decimals, 237}])),
{'EXIT', {badarg, _}} = (catch float_to_binary(
123456789012345678.0, [{decimals, 237}])),
- test_fts("1." ++ string:copies("0", 249) ++ "e+00",
+ test_fts("1." ++ lists:duplicate(249, $0) ++ "e+00",
1.0, [{scientific, 249}, compact]),
X1 = float_to_list(1.0),
@@ -161,6 +161,7 @@ t_float_to_string(Config) when is_list(Config) ->
test_fts("1.000",1.0, [{decimals, 3}]),
test_fts("1.0",1.0, [{decimals, 1}]),
test_fts("1.0",1.0, [{decimals, 3}, compact]),
+ test_fts("10",10.0, [{decimals, 0}, compact]),
test_fts("1.12",1.123, [{decimals, 2}]),
test_fts("1.123",1.123, [{decimals, 3}]),
test_fts("1.123",1.123, [{decimals, 3}, compact]),
@@ -213,6 +214,20 @@ fts_rand_float_decimals(N) ->
[begin
F0 = rand_float_reasonable(),
L0 = float_to_list(F0, [{decimals, D}]),
+ case conform_with_io_lib_format_os(F0,D) of
+ false -> ok;
+ true ->
+ IOL = lists:flatten(io_lib:format("~.*f", [D, F0])),
+ true = case L0 =:= IOL of
+ true -> true;
+ false ->
+ io:format("F0 = ~w ~w\n", [F0, <<F0/float>>]),
+ io:format("decimals = ~w\n", [D]),
+ io:format("float_to_list = ~s\n", [L0]),
+ io:format("io_lib:format = ~s\n", [IOL]),
+ false
+ end
+ end,
L1 = case D of
0 -> L0 ++ ".0";
_ -> L0
@@ -234,6 +249,26 @@ fts_rand_float_decimals(N) ->
fts_rand_float_decimals(N-1).
+conform_with_io_lib_format_os(F, D) ->
+ case os:type() of
+ {win32,_} ->
+ %% io_lib:format("~.*f") buggy on windows? OTP-15010
+ false;
+ _ ->
+ conform_with_io_lib_format(F, D)
+ end.
+
+conform_with_io_lib_format(_, 0) ->
+ %% io_lib:format("~.*f") does not support zero decimals
+ false;
+conform_with_io_lib_format(_, D) when D > 10 ->
+ %% Seems float_to_list gets it slightly wrong sometimes for many decimals
+ false;
+conform_with_io_lib_format(F, D) ->
+ %% io_lib:format prints '0' for input bits beyond mantissa precision
+ %% float_to_list treats those unknown input bits as if they were zeros.
+ math:log2(abs(F) * math:pow(10,D)) < 54.
+
max_diff_decimals(F, D) ->
IntBits = floor(math:log2(abs(F))) + 1,
FracBits = (52 - IntBits),