REPL: Internal error: unhandled encoding (Readline)

[cfa]

The Problem

Intermittent internal errors from Readline, e.g.

$ perl6
> $*ENV<RAKUDO_HIST> ?? $*ENV<RAKUDO_HIST>.IO !! ($*HOME || $*TMPDIR).add('.perl6/rakudo-history');
Internal error: unhandled encoding
  in method CALL-ME at /Users/cfa/.rakudup/2019.03/install/share/perl6/sources/947BDAB9F96E0E5FCCB383124F923A6BF6F8D76B (NativeCall) line 587
  in method readline at /Users/cfa/.rakudup/2019.03/install/share/perl6/site/sources/EBC1B2DDA59A9D91D483BD81DAA416714D2D1276 (Readline) line 1460
^D
$ perl6
$*ENV<RAKUDO_HIST> ?? $*ENV<RAKUDO_HIST>.IO !! ($*HOME || $*TMPDIR).add('.perl6/rakudo-history');
"/Users/cfa/.perl6/rakudo-history".IO

Note how the same input triggers the exception in one run but not the next. This has occurred with a variety of input and seemingly at random—though frequently enough to make the REPL nigh unusable.
Also note that errors usually occur midway through a REPL session; the above was cherrypicked for clarity.

Expected Behavior

Handled encoding!

Actual Behavior

See above.

Following a discussion in #perl6, I also tried with MVM_SPESH_DISABLE=1 and MVM_JIT_DISABLE=1; neither helped:

$ MVM_SPESH_DISABLE=1 p6
To exit type 'exit' or '^D'
> %*ENV<MVM_SPESH_DISABLE>
Internal error: unhandled encoding
  in method CALL-ME at /Users/cfa/.rakudup/2019.03/install/share/perl6/sources/947BDAB9F96E0E5FCCB383124F923A6BF6F8D76B (NativeCall) line 587
  in method readline at /Users/cfa/.rakudup/2019.03/install/share/perl6/site/sources/EBC1B2DDA59A9D91D483BD81DAA416714D2D1276 (Readline) line 1460

> %*ENV<MVM_SPESH_DISABLE>
1

and

$ MVM_JIT_DISABLE=1 p6
To exit type 'exit' or '^D'
> %*ENV<MVM_SPESH_DISABLE>
Internal error: unhandled encoding
  in method CALL-ME at /Users/cfa/.rakudup/2019.03/install/share/perl6/sources/947BDAB9F96E0E5FCCB383124F923A6BF6F8D76B (NativeCall) line 587
  in method readline at /Users/cfa/.rakudup/2019.03/install/share/perl6/site/sources/EBC1B2DDA59A9D91D483BD81DAA416714D2D1276 (Readline) line 1460

> %*ENV<MVM_JIT_DISABLE>
1
> %*ENV<MVM_SPESH_DISABLE>
(Any)

(Again, quite a few runs were required to reproduce the error at the beginning of the session.)

Environment

• Operating system: macOS.
• Compiler version (perl6 -v): 2019.03. Problem first noticed following upgrade from 2018.12.

[cfa]

Potentially related: https://gist.github.com/0racle/c7e65b6946a30479cf8493fbafc04f53.

[cfa]

Also, in case anyone else hits this error: My current workaround is the following wrapper script (p6):

#!/bin/sh

# workaround for https://github.com/rakudo/rakudo/issues/2759
RAKUDO_LINE_EDITOR='none' rlwrap perl6 "$@"

—no need to uninstall Readline or fall back on Linenoise.

[Kaiepi]

I thought this was an OpenBSD exclusive thing since it uses its own version of Readline... huh.
Times like this are when it'd be nice to have wchar_t support so Editline can be used instead of Readline in cases like this or if you just don't like the GPL.

[Kaiepi]

Does this still happen? I can't get the error to appear on HEAD

[AlexDaniel]

Ping @cfa :)

[AlexDaniel]

I also can't reproduce. Blocker label removed.

If anybody stumbles upon this ticket in the future, just close it.