Argument error when calling Float.parse

[joshuap]

We've been having the following error when parsing certain log entries:

17:13:19.057 [error] Task #PID<0.12050.1556> started from #PID<0.15023.1556> terminating
** (ArgumentError) argument error
    :erlang.binary_to_float("358.0e5437")
    (elixir) lib/float.ex:67: Float.parse_unsigned/4
    (logfmt) lib/decoder.ex:146: Logfmt.Decoder.coerce_value/1
    (logfmt) lib/decoder.ex:129: Logfmt.Decoder.put_value/3
    (logfmt) lib/decoder.ex:84: Logfmt.Decoder.parse_char/5
    (my_app) lib/my_app/parser.ex:27: MyApp.Parser.parse_match/1
    (elixir) lib/stream.ex:454: anonymous fn/4 in Stream.map/2
    (elixir) lib/enum.ex:2607: Enumerable.List.reduce/3
Function: #Function<4.74185808/0 in MyApp.Router.process/2>
    Args: []

=CRASH REPORT==== 12-Oct-2015::17:13:19 ===
  crasher:
    initial call: Elixir.MyApp.Router:-process/2-fun-0-/0
    pid: <0.12050.1556>
    registered_name: []
    exception exit: {badarg,
                        [{erlang,binary_to_float,[<<"358.0e5437">>],[]},
                         {'Elixir.Float',parse_unsigned,4,
                             [{file,"lib/float.ex"},{line,67}]},
                         {'Elixir.Logfmt.Decoder',coerce_value,1,
                             [{file,"lib/decoder.ex"},{line,146}]},
                         {'Elixir.Logfmt.Decoder',put_value,3,
                             [{file,"lib/decoder.ex"},{line,129}]},
                         {'Elixir.Logfmt.Decoder',parse_char,5,
                             [{file,"lib/decoder.ex"},{line,84}]},
                         {'Elixir.MyApp.Parser',parse_match,1,
                             [{file,"lib/my_app/parser.ex"},{line,27}]},
                         {'Elixir.Stream','-map/2-fun-0-',4,
                             [{file,"lib/stream.ex"},{line,454}]},
                         {'Elixir.Enumerable.List',reduce,3,
                             [{file,"lib/enum.ex"},{line,2607}]}]}
      in function  'Elixir.Task.Supervised':exit/4 (lib/task/supervised.ex, line 105)
    ancestors: [<0.15023.1556>]
    messages: []
    links: []
    dictionary: []
    trap_exit: false
    status: running
    heap_size: 987
    stack_size: 27
    reductions: 1059
  neighbours:

The issue appears to be in Decoder.coerce_value/1:

https://github.com/jclem/logfmt-elixir/blob/master/lib/decoder.ex#L146

To reproduce the error, try calling Float.parse("358.0e5437") from iex. Could this be a bug in Elixir's implementation of Float.parse/1? I would expect exceptions to be caught and :error returned per the documentation.

[joshuap]

After discussing this error on elixir-lang/elixir#3862 I updated the documentation for Float.parse/1; the ArgumentError can be expected for the time being. I think the solution is to rescue those errors when parsing floats; I'll put together a PR for that if you want me to @jclem.

[jclem]

A PR would be great! Not to get into an unrelated discussion on here, but I'm considering removing the value parsing altogether in a future version, and leaving that up to the user.

On Oct 13, 2015, at 12:05 PM, joshuap notifications@github.com wrote:

After discussing this error on elixir-lang/elixir#3862 I updated the documentation for Float.parse/1; the ArgumentError can be expected for the time being. I think the solution is to rescue those errors when parsing floats; I'll put together a PR for that if you want me to @jclem.

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