Path: utzoo!utgpu!water!watmath!clyde!rutgers!ames!ucbcad!beeblebrox!rudell From: rudell@beeblebrox.uucp (Richard Rudell) Newsgroups: comp.lang.c Subject: Re: X3J11 meeting notes Summary: re-arranging parentheses (integer expressions) Keywords: ANSI C standard Message-ID: <2149@ucbcad.berkeley.edu> Date: 18 Dec 87 03:44:17 GMT References: <6829@brl-smoke.ARPA> <406@mn-at1.UUCP> <6852@brl-smoke.ARPA> <13899@think.UUCP> Sender: news@ucbcad.berkeley.edu Reply-To: rudell@beeblebrox.UUCP (Richard Rudell) Organization: U.C. Berkeley EECS CAD Group Lines: 23 Simple comment on re-arrangement of integer expressions ... Doesn't ANSI leave the affect of integer overflow implementation defined ? (Someone please correct me if this has also changed since the last review draft.) Doesn't this mean that for integer expressions such as: (a - 1) + 1 the compiler is still free to re-arrange the parentheses ? The claim has been made "but if integer traps are enabled, the compiler can't change this". But an ANSI conforming compiler is free to do whatever it wants whenever it wants when integer overflow occurs. Thus, an ANSI compiler can re-arrange these parentheses and still meet the "as if" condition which controls the entire interpretation of the ANSI C specification. The point is, ANSI never promised what might happen if 'a' was the most positive integer. Has this interpretation also changed ? Rick.