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Using Visual Studio 2010. I have a resource.h file which TortoiseHg thinks is binary so it won't display a diff for it in the commit window. I can easily open the file in a text editor and see that it is plain text.

I saw a related question (Why does Mercurial think my SQL files are binary?) which suggests it has to do with file encoding. Indeed opening the file in Notepad++ says the file is in "UCS-2 Little Endian". How can I fix this? I, obviously, don't want to break some Visual Studio expectation.

Community
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User
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2 Answers2

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For display purposes only, Mercurial treats all files containing NUL bytes as binary due to long-standing UNIX convention. This is just about always right.. except for UTF-16 (formerly known as UCS-2).. where half your file is NUL bytes!

Internally, Mercurial treats all files as binary all the time, so this issue is only relevant for things like whether or not we try to display diffs.

So you have two options:

  • ignore it, Mercurial will work just fine
  • use an encoding other than UTF-16

Some web searched for "resource.h utf-16" suggest that VS2010 will be just fine if you save this file in UTF-8 or ASCII, which should be perfectly fine choices for C source code.

http://social.msdn.microsoft.com/Forums/en/vssetup/thread/aff0f96d-16e3-4801-a7a2-5032803c8d83

mpm
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    As described in that thread, from within Visual Studio I opened the resource.h file and went to the menu File->Advanced Save Options and chose the encoding "Unicode (UTF-8 with signature) - Codepage 65001". After two commits I can now see a proper diff. – User Oct 07 '11 at 13:41
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    Correction, upon choosing "Unicode (UTF-8 with signature) - Codepage 65001" after editing in the resource editor Visual Studio complains about the file not being a Visual Studio file. Instead I used "US-ASCII" (as described in the linked thread in this answer). Maybe the problem was the UTF-8 signature? There is an option for no signature, but for now I'm considering the problem solved. – User Oct 07 '11 at 20:26
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    Always prefer the no-signature option. The BOM (the signature in question) is a common source of problems in many programs. And as even without BOM it is relatively simple to auto-detect the difference between UTF-8 and ISO-8859-1 once it contains a character outside the ASCII range, it does not really add value either. – Laurens Holst Oct 08 '11 at 14:10
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Try explicitly converting / changing the encoding to UTF-8 / ASCII and see. You can do that from Notepad++'s Encoding menu ( choose Encode in UTF-8)

Visual Studio will work with the UTF-8 file just fine.

manojlds
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    This not true for the .rc file, tested in Visual Studio 2008 and 2013. I get lots of errors like "error RC2135: file not found: 0x07" when compiling. Resource.h can be UTF-8, though. – Felix Dombek Jul 18 '14 at 18:52