From: "Eregon (Benoit Daloze) via ruby-core" Date: 2022-12-20T12:10:13+00:00 Subject: [ruby-core:111346] [Ruby master Feature#19245] Strict mode for Array#pack that doesn't silently truncate numbers that are too large for the given directive Issue #19245 has been updated by Eregon (Benoit Daloze). FWIW, #15460 was another discussion about "implicit modulo". I'm of the opinion it's better to error there and I think this behavior is rarely if ever wanted. FFI::Pointer does raise for out-of-bounds integers, and that feels very similar to `pack`: ``` > FFI::MemoryPointer.new(16).write_int(2**32) (irb):11:in `write_int32': integer 4294967296 too big to convert to `int' (RangeError) ``` Which seems like the right thing to do, losing data should never be silent IMHO. ---------------------------------------- Feature #19245: Strict mode for Array#pack that doesn't silently truncate numbers that are too large for the given directive https://bugs.ruby-lang.org/issues/19245#change-100720 * Author: byroot (Jean Boussier) * Status: Open * Priority: Normal ---------------------------------------- ```ruby >> [256].pack("C").unpack1("C") => 0 >> [257].pack("C").unpack1("C") => 1 ``` This is specified: ```ruby it "encodes the least significant 32 bits of a negative number" do [ [[-0x0000_0021], "\xdf\xff\xff\xff"], [[-0x0000_4321], "\xdf\xbc\xff\xff"], [[-0x0065_4321], "\xdf\xbc\x9a\xff"], [[-0x7865_4321], "\xdf\xbc\x9a\x87"] ].should be_computed_by(:pack, pack_format()) end ``` But not documented in `Array#pack`. I think that in many case this may lead to silent bugs. ### Possible solutions We could have a strict version of `pack`, either `pack(template, strict: true)` or `pack!(template)`. Or alternatively if we think this is never a desired behavior, we could change `pack` to first warn on truncation and later raise. -- https://bugs.ruby-lang.org/ ______________________________________________ ruby-core mailing list -- ruby-core@ml.ruby-lang.org To unsubscribe send an email to ruby-core-leave@ml.ruby-lang.org ruby-core info -- https://ml.ruby-lang.org/mailman3/postorius/lists/ruby-core.ml.ruby-lang.org/