public inbox for gcc-bugs@sourceware.org help / color / mirror / Atom feed
* [Bug c++/25808] New: constant on rhs of conditional assignment @ 2006-01-16 14:23 dcb314 at hotmail dot com 2006-01-16 15:27 ` [Bug c++/25808] " pinskia at gcc dot gnu dot org ` (3 more replies) 0 siblings, 4 replies; 5+ messages in thread From: dcb314 at hotmail dot com @ 2006-01-16 14:23 UTC (permalink / raw) To: gcc-bugs Given the following C++ source code void g(); void h(); void f( int a, int b) { if (b = 1) // case 1 - fixed constant on rhs. g() always executed. g(); if (b = a) // case 2 - variable on rhs. h() might be executed. h(); } then GNU C++ 4.2 snapshot says dcb@linux:~/C++/Alphasrc> ~/gnu/42-20060114/results/bin/g++ -c -Wall jan15b.cc jan15b.cc: In function 'void f(int, int)': jan15b.cc:6: warning: suggest parentheses around assignment used as truth value jan15b.cc:8: warning: suggest parentheses around assignment used as truth value dcb@linux:~/C++/Alphasrc> We can see the compiler fails to distinguish case 1 and case 2. Suggest enhance the compiler to say something different for case 1. Fixed constant on rhs is much more likely to be a programmer error, IMHO. Here is Intel C++ 9.0 doing what I want jan15b.cc(6): warning #187: use of "=" where "==" may have been intended if (b = 1) ^ -- Summary: constant on rhs of conditional assignment Product: gcc Version: 4.2.0 Status: UNCONFIRMED Severity: enhancement Priority: P3 Component: c++ AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: dcb314 at hotmail dot com GCC host triplet: x86_64-suse-linux http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25808 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/25808] constant on rhs of conditional assignment 2006-01-16 14:23 [Bug c++/25808] New: constant on rhs of conditional assignment dcb314 at hotmail dot com @ 2006-01-16 15:27 ` pinskia at gcc dot gnu dot org 2006-01-16 22:28 ` dcb314 at hotmail dot com ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: pinskia at gcc dot gnu dot org @ 2006-01-16 15:27 UTC (permalink / raw) To: gcc-bugs ------- Comment #1 from pinskia at gcc dot gnu dot org 2006-01-16 15:27 ------- Both of these are questionable, I don't see why there should be a different diagnostic. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25808 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/25808] constant on rhs of conditional assignment 2006-01-16 14:23 [Bug c++/25808] New: constant on rhs of conditional assignment dcb314 at hotmail dot com 2006-01-16 15:27 ` [Bug c++/25808] " pinskia at gcc dot gnu dot org @ 2006-01-16 22:28 ` dcb314 at hotmail dot com 2006-01-17 11:51 ` rguenth at gcc dot gnu dot org 2006-03-08 5:09 ` bangerth at dealii dot org 3 siblings, 0 replies; 5+ messages in thread From: dcb314 at hotmail dot com @ 2006-01-16 22:28 UTC (permalink / raw) To: gcc-bugs ------- Comment #2 from dcb314 at hotmail dot com 2006-01-16 22:28 ------- (In reply to comment #1) > Both of these are questionable, I don't see why there should be a different > diagnostic. Because the two different diagnostics make it easier to grep for. For example, Intel C++ compiler finds case 1, but says nothing about case 2. Easy to grep for. GNU C++ produces the same message for case 1 and case 2, leading to a lot of time wasting manual checking of diagnostics. Surely case 1 is much more likely to be programmer error than case 2 ? -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25808 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/25808] constant on rhs of conditional assignment 2006-01-16 14:23 [Bug c++/25808] New: constant on rhs of conditional assignment dcb314 at hotmail dot com 2006-01-16 15:27 ` [Bug c++/25808] " pinskia at gcc dot gnu dot org 2006-01-16 22:28 ` dcb314 at hotmail dot com @ 2006-01-17 11:51 ` rguenth at gcc dot gnu dot org 2006-03-08 5:09 ` bangerth at dealii dot org 3 siblings, 0 replies; 5+ messages in thread From: rguenth at gcc dot gnu dot org @ 2006-01-17 11:51 UTC (permalink / raw) To: gcc-bugs ------- Comment #3 from rguenth at gcc dot gnu dot org 2006-01-17 11:51 ------- I agree with Pinskia here - also the detection of a constant RHS is difficult and will cause followup PRs that we do not catch all cases. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25808 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug c++/25808] constant on rhs of conditional assignment 2006-01-16 14:23 [Bug c++/25808] New: constant on rhs of conditional assignment dcb314 at hotmail dot com ` (2 preceding siblings ...) 2006-01-17 11:51 ` rguenth at gcc dot gnu dot org @ 2006-03-08 5:09 ` bangerth at dealii dot org 3 siblings, 0 replies; 5+ messages in thread From: bangerth at dealii dot org @ 2006-03-08 5:09 UTC (permalink / raw) To: gcc-bugs ------- Comment #4 from bangerth at dealii dot org 2006-03-08 05:09 ------- I agree with Richard and Andrew. I don't see why we should issue different diagnostics for essentially the same case. W. -- bangerth at dealii dot org changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |bangerth at dealii dot org Status|UNCONFIRMED |RESOLVED Resolution| |WONTFIX http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25808 ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2006-03-08 5:09 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2006-01-16 14:23 [Bug c++/25808] New: constant on rhs of conditional assignment dcb314 at hotmail dot com 2006-01-16 15:27 ` [Bug c++/25808] " pinskia at gcc dot gnu dot org 2006-01-16 22:28 ` dcb314 at hotmail dot com 2006-01-17 11:51 ` rguenth at gcc dot gnu dot org 2006-03-08 5:09 ` bangerth at dealii dot org
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).