[erlang-bugs] Regression on match in 17.0-rc1

Björn Gustavsson <>
Tue Feb 4 10:52:17 CET 2014

On Mon, Feb 3, 2014 at 7:34 PM, José Valim
<> wrote:
> There is a regression in 17.0-rc1. The following code will execute io:format/2 twice:
> -module(test).
> -export([test/0]).
> test() ->
>   X = Y = io:format(<<"foo~n">>),
>   X,
>   Y.

Thanks for the bug report (and thanks Anthony for pointing out the commit).

Here is a correction:

git fetch :bjorng/otp.git bjorn/compiler/optimizations/OTP-11584

Please try it out. We will run it for a couple of days in our daily builds
before merging it to master.


Björn Gustavsson, Erlang/OTP, Ericsson AB

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