------- Comment #2 from lopezibanez at gmail dot com 2006-09-16 01:38 ------- Richard, could you tell which bug report do you mean?
The -Wconversion warnings does not apply to this case. Wconversion warns about the effect of adding a prototype, not about sign conversions. Anyway, I still don't understand where is the bug. Unary minus applied to unsigned (what typically is the type of sizeof()) gives: " `2^n - i', where `n' is the number of bits in the unsigned type." [1] So actually -sizeof(int) is 4294967292 (assuming sizeof(int) is 4). This number fits well in a signed long long. However, it doesn't fit in a signed int, and thus, it wraps around and produces -4. The -Wcoercion flag provided by the Wcoercion project [2] warns for the wrap-around as: pr26298.c:15: warning: coercion as 'int' alters 'unsigned int' constant value [1] http://gcc.gnu.org/ml/gcc/1999-06n/msg00754.html [2] http://gcc.gnu.org/wiki/Wcoercion -- lopezibanez at gmail dot com changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |lopezibanez at gmail dot | |com, rguenth at gcc dot gnu | |dot org http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26298
