Description
I discovered that the XLinkLog.h header redefines the critical system macro __attribute__.
The rule is...don't use, change, or redefine things (e.g. macros) with double underscores. Period no exceptions.
https://devblogs.microsoft.com/oldnewthing/20230109-00/?p=107685
XLink is working around this issue by careful ordering of header includes. Not a good solution. One header that is broken by this issue is libusb.h. Other code/headers may be affected silently.
Setup
- all os, platforms
Repro
- Setup a Windows machine to compile with mingw
- Create any .cpp file in the XLink project, e.g.
src\pc\protocols\myfile.cpp - Edit your cpp file to have the following
#define MVLOG_UNIT_NAME xLinkUsb
#ifdef XLINK_LIBUSB_LOCAL
#include <libusb.h>
#else
#include <libusb-1.0/libusb.h>
#endif
#include "XLink/XLinkLog.h"
int myvar = 1;- config, build
Your build should be successful
Now...change the order so that your file has this code...
#define MVLOG_UNIT_NAME xLinkUsb
#include "XLink/XLinkLog.h"
#ifdef XLINK_LIBUSB_LOCAL
#include <libusb.h>
#else
#include <libusb-1.0/libusb.h>
#endif
int myvar = 1;Result
uncountable number of errors, deep within the system headers, usually related to intrinsics. For example...
[build] C:/Users/WDAGUtilityAccount/Desktop/mingw64/lib/gcc/x86_64-w64-mingw32/12.2.0/include/mmintrin.h: In function '__m64 _mm_cvtsi32_si64(int)':
[build] C:/Users/WDAGUtilityAccount/Desktop/mingw64/lib/gcc/x86_64-w64-mingw32/12.2.0/include/mmintrin.h:79:54: error: cannot convert a vector of type '__vector(2) int' to type '__m64' {aka 'int'} which has different size
[build] 79 | return (__m64) __builtin_ia32_vec_init_v2si (__i, 0);
[build] | ^
[build] C:/Users/WDAGUtilityAccount/Desktop/mingw64/lib/gcc/x86_64-w64-mingw32/12.2.0/include/mmintrin.h: In function 'int _mm_cvtsi64_si32(__m64)':
[build] C:/Users/WDAGUtilityAccount/Desktop/mingw64/lib/gcc/x86_64-w64-mingw32/12.2.0/include/mmintrin.h:122:39: error: cannot convert '__m64' {aka 'int'} to '__vector(2) int'
[build] 122 | return __builtin_ia32_vec_ext_v2si ((__v2si)__i, 0);
[build] | ^~~~~~~~~~~
[build] | |
[build] | __m64 {aka int}
[build] <built-in>: note: initializing argument 1 of 'int __builtin_ia32_vec_ext_v2si(__vector(2) int, int)'
[build] C:/Users/WDAGUtilityAccount/Desktop/mingw64/lib/gcc/x86_64-w64-mingw32/12.2.0/include/mmintrin.h: In function '__m64 _mm_packs_pi16(__m64, __m64)':
[build] C:/Users/WDAGUtilityAccount/Desktop/mingw64/lib/gcc/x86_64-w64-mingw32/12.2.0/include/mmintrin.h:161:43: error: cannot convert '__v4hi' {aka 'short int'} to '__vector(4) short int'
[build] 161 | return (__m64) __builtin_ia32_packsswb ((__v4hi)__m1, (__v4hi)__m2);
[build] | ^~~~~~~~~~~~
[build] | |
[build] | __v4hi {aka short int}
[build] <built-in>: note: initializing argument 1 of '__vector(8) char __builtin_ia32_packsswb(__vector(4) short int, __vector(4) short int)'
Notes
The bug is in include\XLink\XLinkLog.h. It redefines the system macro __attribute__. That is forbidden. And causes chaos like libusb header failures and potentially silent failures elsewhere. For example, in usb_host.cpp 4 local headers and 5+ system headers will no longer have a functioning __attribute__ macro.
XLink/include/XLink/XLinkLog.h
Lines 48 to 53 in d209b7e