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* [Bug c/105581] New: boolean types and relational operators problem @ 2022-05-12 10:11 dcb314 at hotmail dot com 2022-05-12 10:23 ` [Bug c/105581] " pinskia at gcc dot gnu.org ` (5 more replies) 0 siblings, 6 replies; 7+ messages in thread From: dcb314 at hotmail dot com @ 2022-05-12 10:11 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105581 Bug ID: 105581 Summary: boolean types and relational operators problem Product: gcc Version: 12.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c Assignee: unassigned at gcc dot gnu.org Reporter: dcb314 at hotmail dot com Target Milestone: --- For this C code: void g( int ); void f( bool a, bool b) { if (a < b) g( 1); } recent gcc doesn't find a problem: $ /home/dcb/gcc/results/bin/gcc -c -g -O2 -Wall -Wextra -pedantic may12a.cc $ Here is cppcheck complaining: $ /home/dcb/cppcheck/trunk.git/cppcheck --enable=all may12a.cc may12a.cc:6:8: style: Comparison of a variable having boolean value using relational (<, >, <= or >=) operator. [comparisonOfBoolWithBoolError] if (a < b) ^ $ There is an example in the gcc source code: trunk.git/gcc/sreal.h:72:25: style: Comparison of a variable having boolean value using relational (<, >, <= or >=) operator. [comparisonOfBoolWithBoolError] Source code is return negative > other_negative; ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/105581] boolean types and relational operators problem 2022-05-12 10:11 [Bug c/105581] New: boolean types and relational operators problem dcb314 at hotmail dot com @ 2022-05-12 10:23 ` pinskia at gcc dot gnu.org 2022-05-12 10:46 ` schwab@linux-m68k.org ` (4 subsequent siblings) 5 siblings, 0 replies; 7+ messages in thread From: pinskia at gcc dot gnu.org @ 2022-05-12 10:23 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105581 --- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> --- Well. There is a meaning for the code though. That is negative > other_negative Means negative is true while other_negative is false the result will be true which is exactly what it is testing here. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/105581] boolean types and relational operators problem 2022-05-12 10:11 [Bug c/105581] New: boolean types and relational operators problem dcb314 at hotmail dot com 2022-05-12 10:23 ` [Bug c/105581] " pinskia at gcc dot gnu.org @ 2022-05-12 10:46 ` schwab@linux-m68k.org 2022-05-12 11:49 ` dcb314 at hotmail dot com ` (3 subsequent siblings) 5 siblings, 0 replies; 7+ messages in thread From: schwab@linux-m68k.org @ 2022-05-12 10:46 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105581 --- Comment #2 from Andreas Schwab <schwab@linux-m68k.org> --- Equivalent to negative && !other_negative. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/105581] boolean types and relational operators problem 2022-05-12 10:11 [Bug c/105581] New: boolean types and relational operators problem dcb314 at hotmail dot com 2022-05-12 10:23 ` [Bug c/105581] " pinskia at gcc dot gnu.org 2022-05-12 10:46 ` schwab@linux-m68k.org @ 2022-05-12 11:49 ` dcb314 at hotmail dot com 2022-05-12 12:12 ` schwab@linux-m68k.org ` (2 subsequent siblings) 5 siblings, 0 replies; 7+ messages in thread From: dcb314 at hotmail dot com @ 2022-05-12 11:49 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105581 --- Comment #3 from David Binderman <dcb314 at hotmail dot com> --- (In reply to Andrew Pinski from comment #1) > Well. There is a meaning for the code though. > That is negative > other_negative > Means negative is true while other_negative is false the result will be true > which is exactly what it is testing here. In abstract, false and true can't be compared with "<". In the implementation choice of false as 0 and true as 1, then relying on the implementation values does make "<" valid. I think that's the bad style cppcheck is complaining about. It's just better style to have it as a logical expression, as Andreas shows. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/105581] boolean types and relational operators problem 2022-05-12 10:11 [Bug c/105581] New: boolean types and relational operators problem dcb314 at hotmail dot com ` (2 preceding siblings ...) 2022-05-12 11:49 ` dcb314 at hotmail dot com @ 2022-05-12 12:12 ` schwab@linux-m68k.org 2022-10-27 6:45 ` [Bug c/105581] new warning about boolean types and relational operators pinskia at gcc dot gnu.org 2022-10-27 6:45 ` pinskia at gcc dot gnu.org 5 siblings, 0 replies; 7+ messages in thread From: schwab@linux-m68k.org @ 2022-05-12 12:12 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105581 --- Comment #4 from Andreas Schwab <schwab@linux-m68k.org> --- There is nothing abstractly wrong with ordering false and true. ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/105581] new warning about boolean types and relational operators 2022-05-12 10:11 [Bug c/105581] New: boolean types and relational operators problem dcb314 at hotmail dot com ` (3 preceding siblings ...) 2022-05-12 12:12 ` schwab@linux-m68k.org @ 2022-10-27 6:45 ` pinskia at gcc dot gnu.org 2022-10-27 6:45 ` pinskia at gcc dot gnu.org 5 siblings, 0 replies; 7+ messages in thread From: pinskia at gcc dot gnu.org @ 2022-10-27 6:45 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105581 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Blocks| |87403 Summary|boolean types and |new warning about boolean |relational operators |types and relational |problem |operators --- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> --- This is just a style issue really ... Referenced Bugs: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87403 [Bug 87403] [Meta-bug] Issues that suggest a new warning ^ permalink raw reply [flat|nested] 7+ messages in thread
* [Bug c/105581] new warning about boolean types and relational operators 2022-05-12 10:11 [Bug c/105581] New: boolean types and relational operators problem dcb314 at hotmail dot com ` (4 preceding siblings ...) 2022-10-27 6:45 ` [Bug c/105581] new warning about boolean types and relational operators pinskia at gcc dot gnu.org @ 2022-10-27 6:45 ` pinskia at gcc dot gnu.org 5 siblings, 0 replies; 7+ messages in thread From: pinskia at gcc dot gnu.org @ 2022-10-27 6:45 UTC (permalink / raw) To: gcc-bugs https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105581 Andrew Pinski <pinskia at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Severity|normal |enhancement ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2022-10-27 6:45 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2022-05-12 10:11 [Bug c/105581] New: boolean types and relational operators problem dcb314 at hotmail dot com 2022-05-12 10:23 ` [Bug c/105581] " pinskia at gcc dot gnu.org 2022-05-12 10:46 ` schwab@linux-m68k.org 2022-05-12 11:49 ` dcb314 at hotmail dot com 2022-05-12 12:12 ` schwab@linux-m68k.org 2022-10-27 6:45 ` [Bug c/105581] new warning about boolean types and relational operators pinskia at gcc dot gnu.org 2022-10-27 6:45 ` pinskia at gcc dot gnu.org
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