digitalmars.D.bugs - [Issue 10480] New: Warning against wrong usage of incorrect operator for bits set test
- d-bugmail puremagic.com (36/36) Jun 26 2013 http://d.puremagic.com/issues/show_bug.cgi?id=10480
- d-bugmail puremagic.com (18/18) Jun 26 2013 http://d.puremagic.com/issues/show_bug.cgi?id=10480
- d-bugmail puremagic.com (19/33) Jun 26 2013 http://d.puremagic.com/issues/show_bug.cgi?id=10480
- d-bugmail puremagic.com (13/15) Jun 26 2013 http://d.puremagic.com/issues/show_bug.cgi?id=10480
- d-bugmail puremagic.com (22/22) Jun 27 2013 http://d.puremagic.com/issues/show_bug.cgi?id=10480
http://d.puremagic.com/issues/show_bug.cgi?id=10480 Summary: Warning against wrong usage of incorrect operator for bits set test Product: D Version: D2 Platform: All OS/Version: All Status: NEW Keywords: diagnostic Severity: enhancement Priority: P2 Component: DMD AssignedTo: nobody puremagic.com ReportedBy: bearophile_hugs eml.cc The D compiler 2.064alpha gives no warnings here: bool someFunction() { return true; } uint getFlags() { return uint.max; } void main() { uint kFlagValue = 2u ^^ 14; if (someFunction() || getFlags() | kFlagValue) {} } enum INPUT_VALUE = 2; void f(uint flags) { if (flags | INPUT_VALUE) {} } The warning given by Visual Studio 2012: http://msdn.microsoft.com/en-us/library/f921xb29.aspx warning C6316: Incorrect operator: tested expression is constant and non-zero. Use bitwise-and to determine whether bits are set.< More info: http://randomascii.wordpress.com/2013/06/24/two-years-and-thousands-of-bugs-of-/ Perhaps it's a good idea to add this warning to D/dmd. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 26 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10480 Walter Bright <bugzilla digitalmars.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |bugzilla digitalmars.com 15:44:25 PDT --- I'm unhappy with making this an error or a warning. It's perfectly reasonable to write code that tests something that is (at compile time) always true or false. This can happen: 1. in generic code 2. in reasonable attempts to avoid versioning 3. D code idiomatically does quite a bit more at compile time than other languages do. This change would make that more difficult. 4. in temporary debugging code, like: if (0 && condition) ... -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 26 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10480I'm unhappy with making this an error or a warning. It's perfectly reasonable to write code that tests something that is (at compile time) always true or false. This can happen: 1. in generic code 2. in reasonable attempts to avoid versioning 3. D code idiomatically does quite a bit more at compile time than other languages do. This change would make that more difficult. 4. in temporary debugging code, like: if (0 && condition) ...Thank you for your answer. I have opened this issue because: - I think a bit of static analysis from the compiler goes a long way avoiding common simple programmer mistakes. - I think being aware of a problem is important even when I don't know how to solve it, so having this enhancement request in Bugzilla is important to remember it. - In both the article that has spurred this ER and in the warning in the Visual Studio, some intelligent persons think it's a common bug and a good to have warning for C++. I have now gained some experience on how D is designed and how you want it to be designed (nearly no warnings, avoid false positives as much as possible, help generic code and compile time coding), so I understand such problems. If you want I will close down this issue. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 26 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10480 bearophile_hugs eml.cc changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution| |WONTFIX Walter, from: http://forum.dlang.org/post/kqfr0k$52o$1 digitalmars.comWe've discussed this one before. I oppose it, on grounds I added to the enhancement request.So let's close this down, wontfix. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 26 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10480 yebblies <yebblies gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|RESOLVED |REOPENED CC| |yebblies gmail.com Resolution|WONTFIX | I'm not seeing the problem with this here... I agree with Walter, this should be allowed, it happens all the time. if (0 && anything) Same with this: if (1 || anything) But this...? if (1 | anything) At best, they meant to write ||, and this is a typo. At worst, it was supposed to be an && and this is a bug. I think an error here would be very unlikely to be a false positive. I can't think of a single use for a logical or expression as a condition. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 27 2013