[Development] Hardcoded strings and qstricmp comparison

Edward Welbourne edward.welbourne at qt.io
Wed Nov 14 11:03:22 CET 2018

Andy Shaw (14 November 2018 09:34) wrote:
> ... there may be some problems that are connected to using qstricmp
> and other functions that are expecting latin1 strings for one reason
> or another. The reason that this might be a problem is because we are
> encoding our source code as UTF-8 and there is a theoretical problem
> that due to this that we are not protecting the strings correctly to
> ensure that they are treated as latin1 when we explicitly write them
> internally. It could be that reality is that this will never be a
> problem, and if that is the case then please give me the background on
> that so I can pass this on too.
> For user code I get that we can just say that they should do something
> like:
>   qstricmp(str, QLatin1String("a").latin1());
> and that would be ensuring it is correctly seen as a latin1 encoded
> string. If this is how it should be done, then shouldn’t we change our
> usage of it in the Qt code as well to do the same thing? Or am I
> missing something?

Well, as long as the source string is actually printable ASCII, there
should be no problem, as UTF-8 and Latin-1 agree on those.

If the source string contains bytes > 127, such bytes should be encoded
using suitable escapes; if the string is to be read as Latin-1 and the
source file is encoded in UTF-8, the raw form of the bytes would not be
displayed as the character it would actually be read as.

So I'm not quite sure what problem you're referring to, but if a string
in the source is meant to be Latin-1, it shouldn't be entered in literal
form in the source code, it should be entered using escapes,

  QLatin1Char yUmlaut('\xff');

for example.


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