[Bug fortran/94978] [8/9/10/11 Regression] Bogus warning "Array reference at (1) out of bounds in loop beginning at (2)"
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94978 Thomas Koenig changed: What|Removed |Added Status|ASSIGNED|NEW Assignee|tkoenig at gcc dot gnu.org |unassigned at gcc dot gnu.org
[Bug fortran/94978] [8/9/10/11 Regression] Bogus warning "Array reference at (1) out of bounds in loop beginning at (2)"
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94978 Richard Biener changed: What|Removed |Added Priority|P3 |P4
[Bug fortran/94978] [8/9/10/11 Regression] Bogus warning "Array reference at (1) out of bounds in loop beginning at (2)"
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94978 anlauf at gcc dot gnu.org changed: What|Removed |Added CC||trnka at scm dot com --- Comment #4 from anlauf at gcc dot gnu.org --- *** Bug 97320 has been marked as a duplicate of this bug. ***
[Bug fortran/94978] [8/9/10/11 Regression] Bogus warning "Array reference at (1) out of bounds in loop beginning at (2)"
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94978 Thomas Koenig changed: What|Removed |Added Assignee|unassigned at gcc dot gnu.org |tkoenig at gcc dot gnu.org Status|NEW |ASSIGNED --- Comment #3 from Thomas Koenig --- Let's see what can be done about this.(In reply to Thomas Koenig from comment #2) > Two ways to fix this: When checking for outer do loops, also check > if the inner one will be executed at all. > > Or PR 90302, which is looking more attractive than ever.
[Bug fortran/94978] [8/9/10/11 Regression] Bogus warning "Array reference at (1) out of bounds in loop beginning at (2)"
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94978 Thomas Koenig changed: What|Removed |Added Ever confirmed|0 |1 Blocks||90302 Status|UNCONFIRMED |NEW Last reconfirmed||2020-05-18 CC||tkoenig at gcc dot gnu.org --- Comment #2 from Thomas Koenig --- Two ways to fix this: When checking for outer do loops, also check if the inner one will be executed at all. Or PR 90302, which is looking more attractive than ever. Referenced Bugs: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=90302 [Bug 90302] Implement __builtin_warning
[Bug fortran/94978] [8/9/10/11 Regression] Bogus warning "Array reference at (1) out of bounds in loop beginning at (2)"
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94978 Richard Biener changed: What|Removed |Added Target Milestone|--- |8.5 Keywords||diagnostic
[Bug fortran/94978] [8/9/10/11 Regression] Bogus warning "Array reference at (1) out of bounds in loop beginning at (2)"
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94978 --- Comment #1 from Fritz Reese --- The regression is caused by r253156, which introduces the warning in the first place. The relevant code is in frontend-passes.c (do_subscript). Apparently, the FE is aware that when there is a conditional it cannot correctly simplify the subscript bounds. However, in the testcase there is an inner DO-loop which, when the bounds are reduced to the empty set, prevents the code from becoming invalid. Therefore no warning should be issued. The warning can be bypassed by guarding the inner DO-loop with any conditional, including a vacuously true one: $ diff -auw pascal.f03 pascal2.f03 --- pascal.f03 2020-05-06 19:14:50.966646632 -0400 +++ pascal2.f03 2020-05-06 19:23:48.209569659 -0400 @@ -9,9 +9,11 @@ do i = 0, 8 pascal(i,0) = 1 + if (.true.) then do j = 1, i-1 pascal(i,j) = pascal(i-1,j) + pascal(i-1,j-1) enddo + endif do j = i, 8 pascal(i,j) = 0 enddo $ gfortran pascal2.f03 Normally the warning can be suppressed with -Wno-do-subscript, but the code in do_subscript() determines that this is "definitely" an issue and therefore moves the warning to category 0. (An interesting note: moving the code in the testcase into a subroutine, rather than the main program, suppresses the warning for GCC 8, but not GCC 9, 10, or 11.)
