Not sure why this test fails:

Use of uninitialized value $codepage in concatenation (.) or string at D:\a\ExtUtils-MakeMaker\ExtUtils-MakeMaker\blib\lib/ExtUtils/MakeMaker.pm line 229.
Unknown encoding 'cp' at D:\a\ExtUtils-MakeMaker\ExtUtils-MakeMaker\blib\lib/ExtUtils/MakeMaker.pm line 229.
# Looks like you planned 11 tests but ran 9.
# Looks like your test exited with 255 just after 9.
t/prompt.t ................ 

The test does not fail on my laptop..

Not sure why this test fails:

Use of uninitialized value $codepage in concatenation (.) or string at D:\a\ExtUtils-MakeMaker\ExtUtils-MakeMaker\blib\lib/ExtUtils/MakeMaker.pm line 229.
Unknown encoding 'cp' at D:\a\ExtUtils-MakeMaker\ExtUtils-MakeMaker\blib\lib/ExtUtils/MakeMaker.pm line 229.
# Looks like you planned 11 tests but ran 9.
# Looks like your test exited with 255 just after 9.
t/prompt.t ................ 

The test does not fail on my laptop..

Perhaps in your p.r. at line 223 the return value was an empty string. That would be a defined value, but then at 229 the first argument to decode would only be cp.

Perhaps in your p.r. at line 223 the return value was an empty string

@jkeenan Added a test for empty string, see last commit

I'm not sure if we can use Encode here like that; MakeMaker is part of perl's bootstrap which means it's used before Encode is built. ExtUtils::MakeMaker::Locale is some prior art in this area.

I'm not sure if we can use Encode here like that

Then as an alternative, would it be possible to apply this patch to e.g. IO::Prompt::Tiny instead and patch consumers like CPAN::Shell to use IO::Prompt::Tiny::prompt as a replacement for ExtUtils::MakeMaker::prompt ?

Then as an alternative, would it be possible to apply this patch to e.g. IO::Prompt::Tiny instead and patch consumers like CPAN::Shell to use IO::Prompt::Tiny::prompt as a replacement for ExtUtils::MakeMaker::prompt ?

No. CPAN::Shell is core so can't use any module outside of core.

And I didn't you can't use Encode at all, I'm just saying it should handle its absence gracefully.

ExtUtils::MakeMaker::Locale is some prior art in this area.

Yes, nice one! For reference here is a link to the PR from 2014: #125

MakeMaker is part of perl's bootstrap which means it's used before Encode is built.

@Leont But why then can ExtUtils::MakeMaker::Locale use Encode itself? See line 15:

@Leont But why then can ExtUtils::MakeMaker::Locale use Encode itself? See line 15:

Because this

I'm not sure if we can use Encode here like that

Trying with ExtUtils::MakeMaker::Locale instead, see latest commit. Also added a test case.