------- Comment #7 from manu at gcc dot gnu dot org 2009-07-09 15:35 ------- @Jacob,
The C/C++ standards have some precise rules of what can and cannot be done about pointer casts. See http://gcc.gnu.org/onlinedocs/gcc-4.4.0/gcc/Optimize-Options.html#index-fstrict_002daliasing-749 See also the documentation of -Wstrict-aliasing. This is warned by GCC by using -Wall. m...@localhost:~$ gcc --version gcc (GCC) 4.2.4 (Ubuntu 4.2.4-1ubuntu4) Copyright (C) 2007 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. m...@localhost:~$ g++ -Wall -O2 pr40698.c -c pr40698.c: In function TwoPointers InterlockedExchange(TwoPointers*, TwoPointers): pr40698.c:55: warning: dereferencing type-punned pointer will break strict-aliasing rules pr40698.c:55: warning: dereferencing type-punned pointer will break strict-aliasing rules pr40698.c:56: warning: dereferencing type-punned pointer will break strict-aliasing rules pr40698.c: In function int main(): pr40698.c:80: warning: dereferencing type-punned pointer will break strict-aliasing rules pr40698.c:81: warning: dereferencing type-punned pointer will break strict-aliasing rules pr40698.c:63: warning: unused variable i pr40698.c:64: warning: unused variable j If you have more questions, please do ask. -- manu at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |manu at gcc dot gnu dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=40698
