Date: Thu, 15 Nov 2012 08:26:03 -0500 From: Rich Felker <dalias@...ifal.cx> To: musl@...ts.openwall.com Subject: Re: type of wchar_t On Thu, Nov 15, 2012 at 04:36:31PM +0400, Yuri Kozlov wrote: > > so we either use the __WCHAR_TYPE__ defined by the > > compiler (when it's defined), or use the abi specs > > (which gives the align+size+sign information and > > hopefully compilers agree on a single int type when > > there are multiple choices) > > Thanks for clarification. > Hah, gcc emit a __WCHAR_TYPE__ for arm as unsigned. Wow. > $ arm-linux-gnueabi-gcc -dM -E - < /dev/null |grep __WCHAR_T > #define __WCHAR_TYPE__ unsigned int Yes. Whoever designed this aspect of the ARM EABI did not know what they were doing. They probably came from a Windows background where wchar_t is unsigned short (to be able to represent all of the Unicode BMP) and did not realize that making it unsigned is unnecessary and even harmful when it's 32-bit and thus able to store all of Unicode (and much more) in a signed type. As already explained, I wanted to just always use a signed type on musl, but since L"" must match the type of wchar_t* (otherwise, passing L"" to a function that expects wchar_t* is a constraint violation and the compiler should throw an error), we need the definition to agree with whatever the compiler thinks it is, and real-world compilers follow the EABI document that defines it as unsigned. Rich
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