On Sat, Sep 21, 2013 at 06:24:13PM +0100, Jonathan Wakely wrote: > On 21 September 2013 17:46, wrote: > > Is it possible for gcc to produce a > > warning in such situation? > > If ab and bc are 'const' then G++ will warn: > > o.cc: In function ‘int main()’: > o.cc:5:14: warning: integer overflow in expression [-Woverflow] > int r = ab * bc; > ^ > > The C compiler still doesn't warn though, due to different rules for > how constants are handled between C and C++. Hmm, I don't know too much about C++ but why would a C++ compiler produce a warning only if two operands were const? I learned that in C `const' modifier only means that I promise to the compiler that this variable will be read-only, its value can be changed using pointers but the result is undefined and that const != constant expression. So are the differences in const between C and C++ so much complex or is it just a compiler that decides to act this way? From what you said, I believe the differnces are more complex than I thought. Anyway, do you know how to make gcc warn about this in pure C? -- <wempwer@xxxxxxxxx>
