[Bug fortran/87606] New: Wrong array reference out of bounds warning

[AstroFloyd at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87606

Bug ID: 87606
   Summary: Wrong array reference out of bounds warning
   Product: gcc
   Version: 8.2.0
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: fortran
  Assignee: unassigned at gcc dot gnu.org
  Reporter: AstroFloyd at gmail dot com
  Target Milestone: ---

The following Fortran program (minimum working example) gives an erroneous
array reference out of bounds warning:

program test
  implicit none
  integer :: i,iarr(10)
  do i=1,10
 if(i.gt.1) iarr(i-1) = i
  end do
end program test


$ gfortran -Wdo-subscript test.f90 -o test
test.f90:5:21:

   do i=1,10
   2  
  if(i.gt.1) iarr(i-1) = i
 1
Warning: Array reference at (1) out of bounds (0 < 1) in loop beginning at (2)
[-Wdo-subscript]

[Bug fortran/57127] New: gfortran gives unintended warning on uninitialized optional dummy array of undetermined size

[AstroFloyd at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57127

 Bug #: 57127
   Summary: gfortran gives unintended warning on uninitialized
optional dummy array of undetermined size
Classification: Unclassified
   Product: gcc
   Version: 4.7.2
Status: UNCONFIRMED
  Severity: normal
  Priority: P3
 Component: fortran
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: astrofl...@gmail.com


Created attachment 29985
  -- http://gcc.gnu.org/bugzilla/attachment.cgi?id=29985
Source file example.f90 used in the example in the bug report

gfortran-4.7.2 -O1 -Wall gives unintended warning about uninitialized array
elements when a routine is called with an optional dummy array of undetermined
size (example.f90 is attached below):

$ gfortran -O1 -Wall example.f90 -o example  ./example
example.f90: In function ‘example_routine’:
example.f90:8:0: warning: ‘array.0’ may be used uninitialized in this function
[-Wmaybe-uninitialized]

Expected behaviour: no warning message.

The warning goes away when:
  * -O0 is used rather than -O1 or higher
  * -Wall is replaced by -Wmaybe-uninitialized
  * the line  write(op,'(A)') 'foo'  is commented out

[Bug fortran/57127] gfortran gives unintended warning on uninitialized optional dummy array of undetermined size

[AstroFloyd at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57127



--- Comment #2 from AstroFloyd AstroFloyd at gmail dot com 2013-04-30 
20:57:55 UTC ---

Hmmm, this looks very strongly like

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52370 but is not identical(?)

[Bug fortran/55352] Erroneous gfortran warning of unused module variable when variable is only used in namelist

[AstroFloyd at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55352



--- Comment #5 from AstroFloyd AstroFloyd at gmail dot com 2012-11-18 
17:53:36 UTC ---

Created attachment 28726

  -- http://gcc.gnu.org/bugzilla/attachment.cgi?id=28726

My adaptation of the patch in #3



This solves the problem for me, thank you very much - I'm impressed by your

quick and competent work :-)



Somehow, your patch didn't work in my Gentoo version; I applied your changes

manually and created the attached patch, which can be added to the Gentoo

ebuild for sys-devel/gcc-4.7.2.

[Bug fortran/55352] New: Erroneous gfortran warning of unused module variable when variable is only used in namelist

[AstroFloyd at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55352



 Bug #: 55352

   Summary: Erroneous gfortran warning of unused module variable

when variable is only used in namelist

Classification: Unclassified

   Product: gcc

   Version: 4.7.2

Status: UNCONFIRMED

  Severity: normal

  Priority: P3

 Component: fortran

AssignedTo: unassig...@gcc.gnu.org

ReportedBy: astrofl...@gmail.com





Created attachment 28709

  -- http://gcc.gnu.org/bugzilla/attachment.cgi?id=28709

Minimal example source code



gfortran-4.7.2 -Wall gives a warning about unused module variables when those

variables are only used in a namelist.



Test: compile the attached minimal example source file test.f90 with:

gfortran -v -Wall -Werror test.f90 -o test



The following warning is printed:

test.f90:14.6:



  use data, only: a

  1

Warning: Unused module variable 'a' which has been explicitly imported at (1)



The warning goes away when print*,a is uncommented in line 20.  Verbose output

is in the attached file compile_output.txt





Get: warning about unused module variable

Expect:  no warning

Reproduceable:  always

gfortran version: gcc version 4.7.2 (Gentoo 4.7.2 p1.3, pie-0.5.5)

[Bug fortran/55352] Erroneous gfortran warning of unused module variable when variable is only used in namelist

[AstroFloyd at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55352



--- Comment #1 from AstroFloyd AstroFloyd at gmail dot com 2012-11-16 
13:43:25 UTC ---

Created attachment 28710

  -- http://gcc.gnu.org/bugzilla/attachment.cgi?id=28710

Verbose output from compilation of example source file