On Thu, 21 Dec 2006, Paul Eggert wrote: > But because bigtime_test wants an int, this causes the test > program to compute the equivalent of (int) ((unsigned int) > INT_MAX + 1), and C99 says that if you cannot assume > wrapping semantics this expression has undefined behavior in > the common case where INT_MAX < UINT_MAX.
Conversion of out-of-range integers to signed types is implementation-defined not undefined, and GCC duly documents the modulo semantics for that conversion. I don't know if you have to deal with compilers applying different semantics there, but shared overflow checking functions in gnulib could deal with the differences between compilers. (Conversion of out-of-range floating-point numbers to integer types *is* undefined, but Annex F changes this to returning an unspecified value so bounding the possible behavior, and I believe GCC follows Annex F for this: it's useful not to have to guarantee any particular result, since different machines have conversion instructions that may do different things for out-of-range values, and to be able to return different results for compile-time and run-time conversions, but floating-point conversions don't have the same scope as integer arithmetic for useful optimization based on undefined behavior.) -- Joseph S. Myers [EMAIL PROTECTED]
