Gfortran uninitialized warnings

2

Yes, the -Wuninitialized option of gfortran produces so many false positives that it should usually be turned off, especially if you use the allocation-on-assignment feature of Fortran. For example, for the code

implicit none
integer, allocatable :: v(:)
v = [10,20]
print*,v
end

you get

c:\fortran\test>gfortran -Wall -Wextra xgfortran_warn.f90
xgfortran_warn.f90:3:11:

    3 | v = [10,20]
      |           ^
Warning: 'v.offset' is used uninitialized [-Wuninitialized]
xgfortran_warn.f90:2:28:

    2 | integer, allocatable :: v(:)
      |                            ^
note: 'v' declared here
xgfortran_warn.f90:3:11:

    3 | v = [10,20]
      |           ^
Warning: 'v.dim[0].lbound' is used uninitialized [-Wuninitialized]
xgfortran_warn.f90:2:28:

    2 | integer, allocatable :: v(:)
      |                            ^
note: 'v' declared here
xgfortran_warn.f90:3:11:

    3 | v = [10,20]
      |           ^
Warning: 'v.dim[0].ubound' is used uninitialized [-Wuninitialized]
xgfortran_warn.f90:2:28:

    2 | integer, allocatable :: v(:)
      |                            ^
note: 'v' declared here
xgfortran_warn.f90:3:11:

    3 | v = [10,20]
      |           ^
Warning: 'v.dim[0].lbound' may be used uninitialized [-Wmaybe-uninitialized]
xgfortran_warn.f90:2:28:

    2 | integer, allocatable :: v(:)
      |                            ^
note: 'v' declared here
xgfortran_warn.f90:3:11:

    3 | v = [10,20]
      |           ^
Warning: 'v.dim[0].ubound' may be used uninitialized [-Wmaybe-uninitialized]
xgfortran_warn.f90:2:28:

    2 | integer, allocatable :: v(:)
      |                            ^
note: 'v' declared here
xgfortran_warn.f90:3:11:

    3 | v = [10,20]
      |           ^
Warning: 'v.dim[0].ubound' may be used uninitialized [-Wmaybe-uninitialized]
xgfortran_warn.f90:2:28:

    2 | integer, allocatable :: v(:)
      |                            ^
note: 'v' declared here
xgfortran_warn.f90:3:11:

    3 | v = [10,20]
      |           ^
Warning: 'v.dim[0].lbound' may be used uninitialized [-Wmaybe-uninitialized]
xgfortran_warn.f90:2:28:

    2 | integer, allocatable :: v(:)
      |                            ^
note: 'v' declared here

for gfortran 12.0.1 20220213.

gfortran -Wall -Wextra -Wno-uninitialized xgfortran_warn.f90

is appropriately silent.

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