Warning at compilation due to potentially uninitialised variable

A warning is produced by GCC Fortran compiler while installing airGR version 1.6.9.27, due to a may be uninitialized variable.

How to reproduce the bug?

1. Clone master branch of repository at commit 88db83a415ac97742353fc06245c40255535f6e7
2. Run R CMD build airgr
3. Run R CMD INSTALL airGR_1.6.9.27.tar.gz

Used software: openSUSE Leap 15.2 with Linux 5.3.18-lp152.60-default kernel; GNU Fortran 11.0.0 20210122 for SUSE Linux; R version 4.0.3

Compilation flags: -fno-optimize-sibling-calls -fpic -std=f2018 -fmessage-length=0 -grecord-gcc-switches -O3 -Wall -pedantic -D_FORTIFY_SOURCE=2 -fstack-protector-strong -funwind-tables -fasynchronous-unwind-tables -fstack-clash-protection

Expected behaviour

Compilation and installation without warning.

Actual behaviour

Warning while compiling frun_GR5H.f90:

gfortran -fno-optimize-sibling-calls  -fpic  -std=f2018 -fmessage-length=0 -grecord-gcc-switches -O3 -Wall -pedantic -D_FORTIFY_SOURCE=2 -fstack-protector-strong -funwind-tables -fasynchronous-unwind-tables -fstack-clash-protection  -c  frun_GR5H.f90 -o frun_GR5H.o
frun_GR5H.f90:93:26:

   93 |       IF (IsIntStore .EQV. .TRUE.) St(3) = StateStart(4)
      |                          ^
Avertissement: « isintstore » may be used uninitialized [-Wmaybe-uninitialized]
frun_GR5H.f90:71:27:

   71 |       logical :: IsIntStore         ! TRUE if interception store is used, FALSE otherwise
      |                           ^
note: « isintstore » déclaré ici

Proposed solution

Change lines 79 and 80 of frun_GR5H.f90 to an if-else statement:

      IF (Imax .LT. 0.) THEN
        IsIntStore = .FALSE.
      ELSE
        IsIntStore = .TRUE.
      ENDIF