Re: patch applied (cabal): Make UTF-8 decoding errors in .cabal files non-fatal

In message <20080327160333.GA10636@soi.city.ac.uk> cabal-devel@haskell.org writes:

On Thu, Mar 27, 2008 at 08:45:29AM -0700, Duncan Coutts wrote:

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Wed Mar 26 20:17:40 PDT 2008 Duncan Coutts * Make UTF-8 decoding errors in .cabal files non-fatal Previously we checked for invalid UTF-8 in the first phase of the parser, which splitting the file up into nested sections and fields. This meant the whole parser falls over if there is invalid UTF-8 anywhere in the file. Sadly there are already packages on hackage with invalid UTF-8 so we would fail when parsing the hackage index. The solution is to move the check into the parsing of the individual fields and making it a warning not an error. We most typically get invalid UTF-8 in free text fields like author name, copyright, description etc so this should work out ok usually. We now get pretty decent error messages, like: Warning: hsx.cabal:5: Invalid UTF-8 text in the 'author' field. The warning type is now structured so that hackage will be able to distinguish general non-fatal warnings from UTF-8 decoding problems which really should be fatal errors for package uploads.

These invalid UTF-8 strings are usually valid Latin-1 in people's names, which the web interface needs to show.

Can't we just reject them with the error message and ask people to fix the latin-1 sequences and re-upload using proper UTF-8? Is the web interface sending UTF-8 now? I don't know if we've done an end-to-end test yet. If we have then we should close ticket #145: http://hackage.haskell.org/trac/hackage/ticket/145

So would it be possible give the warning, but either to treat bytes that comprise an encoding error as Latin-1 Chars, or to reparse a string (or file) with UTF errors as a Latin-1 string? In almost all cases, the problematic sequence is a single non-ASCII byte surrounded by ASCII bytes.

I really don't think we should continue to allow mixed/undefined encodings. We should be strict about enforcing UTF-8, but of course we should provide helpful error messages to make it easy for people to make the corrections. So I think hackage should reject them with a suitable error message. I can send a patch. On that topic in fact, I think all parser warnings should be fatal errors as far as hackage is concerned. I'll send a separate patch for that. The more permissive hackage is, the more legacy of weird corner cases we accumulate. You suggested previously that we should add a warning for the cases where an isolated latin-1 char in someone's name turns out to be valid UTF-8 (but encoding for an unexpected char). I think that's a good idea. Obviously that'd want to be a non-fatal warning. Hmm, I now can't find the note where you made that suggestion. Can you give more details on how that check would work exactly? Duncan