Re: [HACKERS] Tightening isspace() tests where behavior should match SQL parser - Mailing list pgsql-hackers

From Tom Lane
Subject Re: [HACKERS] Tightening isspace() tests where behavior should match SQL parser
Date
Msg-id 1716.1495572263@sss.pgh.pa.us
Whole thread Raw
In response to Re: [HACKERS] Tightening isspace() tests where behavior should matchSQL parser  (Heikki Linnakangas <hlinnaka@iki.fi>)
Responses Re: [HACKERS] Tightening isspace() tests where behavior should match SQL parser  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Heikki Linnakangas <hlinnaka@iki.fi> writes:
> On 05/20/2017 01:48 PM, Tom Lane wrote:
>> Attached is a proposed patch.  I'm vacillating on whether to
>> back-patch this --- it will fix a reported bug, but it seems
>> at least somewhat conceivable that it will also break cases
>> that were working acceptably before.  Thoughts?

> +1 for back-patching. If I understand correctly, it would change the 
> behavior when you pass a string with non-ASCII leading or trailing 
> whitespace characters to those functions. I suppose that can happen, but 
> it's only pure luck if the current code happens to work in that case. 

Well, it'd work properly for e.g. no-break space in LATINn.  But that
seems like a very narrow use-case, and probably not enough to justify
the misbehavior you might get in multi-byte character sets.

A compromise possibly worth considering is to apply isspace() only in
single-byte encodings.  I think that's more complication than it's
worth, but others might think differently.
        regards, tom lane



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