Ruby

Possibly we should raise an exception if the string is not ascii_only?

I agree that at the very least the unknown pack directive warning should be made non-verbose (displayed even with $VERBOSE=false, and would make sense as ArgumentError.

Agreed, I think it should be ArgumentError since it's otherwise silently ignoring characters in the pack format string.
A non-verbose warning is better than the current state if ArgumentError is deemed too incompatible.

Here is real case where the silent warning caused confusion for [1].pack('<L'): https://github.com/oracle/truffleruby/issues/2791

EDIT: extracted to #19150

chrisseaton (Chris Seaton) wrote in #note-1:

Possibly we should raise an exception if the string is not ascii_only?

I think you want to mean "if the string is not ASCII-compatible".

https://github.com/ruby/ruby/pull/6785

I think you want to mean "if the string is not ASCII-compatible".

Can you explain why?

I think a string is only a valid pack format string if it is ascii_only? - if it isn't ascii_only? then there is a silent warning and the output encoding is changed. We're proposing raising an error up front if the string is not ascii_only?.

Checking ascii_only? would reject non-ascii comments which are fine:

p [2, 89].pack(<<~PACK)
  C # 🚗
  c
PACK
p [2, 89].pack('Cc')
# Same output

Template strings should be ASCII compatible, exceptions otherwise.

Matz.