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Date: | Wed, 04 Feb 2009 03:26:07 -0500 |
From: | Charles Wilson <cygwin AT cwilson DOT fastmail DOT fm> |
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To: | cygwin AT cygwin DOT com |
Subject: | Re: "Incompatible" typedefs |
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Christopher Faylor wrote: > On Tue, Feb 03, 2009 at 12:06:49PM -0500, Charles Wilson wrote: >> I ran across an oddity in the cygwin headers today. > > This boils down to "What does linux do?". If we are doing something > different then PTC. Errr, it's a little weird. On linux, I have: From <sys/types.h> typedef unsigned int u_int8_t __attribute__ ((__mode__ (__QI__))); typedef unsigned int u_int16_t __attribute__ ((__mode__ (__HI__))); typedef unsigned int u_int32_t __attribute__ ((__mode__ (__SI__))); typedef unsigned int u_int64_t __attribute__ ((__mode__ (__DI__))); From <stdint.h> typedef unsigned char uint8_t; typedef unsigned short int uint16_t; typedef unsigned int uint32_t; From <bits/types.h> typedef signed char __int8_t; typedef unsigned char __uint8_t; typedef signed short int __int16_t; typedef unsigned short int __uint16_t; typedef signed int __int32_t; typedef unsigned int __uint32_t; So it looks like everything is defined in terms of ANSI C types (int, char, etc) without the intermediation that cygwin's headers use. So, all of the [__]u[_]int32_t types are all 'unsigned int'. I'm guessing that "__attribute__ ((__mode__ (__SI__)))" doesn't make u_int32_t different than uint32_t. But apparently there is some heavy duty compiler magic happening, because I would have thought that these two: typedef unsigned int u_int16_t __attribute__ ((__mode__ (__HI__))); typedef unsigned short int uint16_t; are very different. But they are not (in that a variation of my test case I posted earlier, emits no warnings with these two types). I'm not sure what useful conclusions we can draw from looking at how linux does it, Or maybe I just need some sleep. -- Chuck -- Unsubscribe info: http://cygwin.com/ml/#unsubscribe-simple Problem reports: http://cygwin.com/problems.html Documentation: http://cygwin.com/docs.html FAQ: http://cygwin.com/faq/
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