------- Additional Comments From pinskia at gcc dot gnu dot org 2005-06-27 21:02 ------- (In reply to comment #21) > 1. Sometimes using "undefined" simplifies the compiler and improves > generated code. > 2. (OTOH) Undefind situations are unhelpful the the users, they complicate > debugging, and make programming harder. Reducing rules that imply > undefined behavior semantics is good for the users.
No I disagree with that, most undefined behaviors are very easy to debug, the most obvious one and most invoked undefined behavior in terms of bug reports is violating C/C++ aliasing rules (see PR 21920 which has 69 duplicates). In fact if you look at GCC, it is the only compiler were people run into violating C/C++ aliasing rules beause we use them to check if two addresses can alias. This is unlike almost all other compilers which represent their aliasing info as base+address and they only invoke the C/C++ aliasing rules when they cannot figure out if they point to the same address. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22200
