ERL-778: Internal consistency check failed - uninitialized register

[OTP-Maintainer]

Original reporter: emfa
Affected version: OTP-21.1.1
Fixed in version: OTP-21.2
Component: compiler
Migrated from: https://bugs.erlang.org/browse/ERL-778

---

When trying to compile our project with 21 for the first time I got an error and was told to report this. I tried to de still the function to the smallest possible which still failed. Have not had time to do any more digging.


{code:erlang}
-module(test).

-export([test/2]).

test(F, M) ->
    NewValue = case is_function(F, 0) of
                true -> F();
                false when F =:= undefined -> undefined
            end,
    case NewValue of
        undefined -> undefined;
        _ -> M#{test => NewValue}
    end.
{code}


{noformat}
emfa >> erlc /tmp/test.erl
test: function test/2+6:
  Internal consistency check failed - please report this bug.
  Instruction: {bif,is_function,{f,0},[{x,0},{integer,0}],{x,2}}
  Error:       {uninitialized_reg,{y,0}}:
{noformat}

[OTP-Maintainer]

bjorn said:

Thanks for the bug report.

Here is a fix:

https://github.com/erlang/otp/pull/2025

The correction will be included in OTP 21.2.