[Bug fortran/98701] I compiled a program with gfortran on Mac (Big Sur, version 11.1) and g77 on Windows 10. I get two very different results for identical input files with the results from the one compiled by gfortran being wrong.

[tkoenig at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98701

Thomas Koenig <tkoenig at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |tkoenig at gcc dot gnu.org

--- Comment #15 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
Just one final remark.

Using gfortran -O2 -Wall FiberAnalysis.f

will give you

FiberAnalysis.f:146:72:

  146 |       if(eincr.gt.0) xnumber=(esfinal-estart)/eincr
      |                                                                       
^
Warnung: »estart« may be used uninitialized [-Wmaybe-uninitialized]
FiberAnalysis.f:146:44:

  146 |       if(eincr.gt.0) xnumber=(esfinal-estart)/eincr
      |                                            ^
Hinweis: »estart« ist hier deklariert
FiberAnalysis.f:148:9:

  148 |       if(xnumber.gt.500) then
      |         ^
Warnung: »xnumber« könnte in dieser Funktion uninitialisiert verwendet werden
[-Wmaybe-uninitialized]


which pretty well shows where problems could occur.