Bug#920022: gfortran: doesn't generate reproducibly the same object file for an unchanged fortran source file
Package: gfortran
Version: 4:8.2.0-2
Severity: normal
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Hi,
I'm filing this bug against gfortran because I can't find any related
piece of information anywhere about this reproducibility problem.
I'm just one step to achieve the Reproducible builds goal for the code-saturne
package, but I'm stuck with unreproducible fortran builds [1].
[1] https://tests.reproducible-builds.org/debian/dbdtxt/unstable/armhf/code-saturne_5.3.1+repack-8.diffoscope.txt.gz
I've narrowed the problem to - at least - one source file: src/base/clptur.f90.
Steps to reproduce:
1- Run a first build code-saturne 5.3.1+repack-8 against unstable
2- In the src/base subdirectory, run this command several times:
gfortran -I../../src -I../../src/alge -I../../src/atmo -I../../src/cfbl -I../../src/cogz -I../../src/comb -I../../src/ctwr -I../../src/darc -I../../src/elec -I../../src/lagr -I../../src/pprt -I../../src/rayt -I../../src/turb -I../../src/user -O -x f95-cpp-input -Wall -pedantic-errors -std=f2003 -fdiagnostics-color=auto -g -O2 -fdebug-prefix-map=$(readlink -f ../..)=. -fstack-protector-strong -fopenmp -c clptur.f90 -fPIC -o .libs/clptur.o 2>/dev/null && readelf -a .libs/clptur.o | grep ntlast && ls -l .libs/clptur.o
Here is an example of what I obtain after two runs in a row:
$ gfortran -I../../src -I../../src/alge -I../../src/atmo -I../../src/cfbl -I../../src/cogz -I../../src/comb -I../../src/ctwr -I../../src/darc -I../../src/elec -I../../src/lagr -I../../src/pprt -I../../src/rayt -I../../src/turb -I../../src/user -O -x f95-cpp-input -Wall -pedantic-errors -std=f2003 -fdiagnostics-color=auto -g -O2 -fdebug-prefix-map=$(readlink -f ../..)=. -fstack-protector-strong -fopenmp -c clptur.f90 -fPIC -o .libs/clptur.o 2>/dev/null && readelf -a .libs/clptur.o | grep ntlast && ls -l .libs/clptur.o
9: 0000000000000000 4 OBJECT LOCAL DEFAULT 3 ntlast.4720
- -rw-rw-r-- 1 pini pini 182504 Jan 21 09:07 .libs/clptur.o
$ gfortran -I../../src -I../../src/alge -I../../src/atmo -I../../src/cfbl -I../../src/cogz -I../../src/comb -I../../src/ctwr -I../../src/darc -I../../src/elec -I../../src/lagr -I../../src/pprt -I../../src/rayt -I../../src/turb -I../../src/user -O -x f95-cpp-input -Wall -pedantic-errors -std=f2003 -fdiagnostics-color=auto -g -O2 -fdebug-prefix-map=$(readlink -f ../..)=. -fstack-protector-strong -fopenmp -c clptur.f90 -fPIC -o .libs/clptur.o 2>/dev/null && readelf -a .libs/clptur.o | grep ntlast && ls -l .libs/clptur.o
9: 0000000000000000 4 OBJECT LOCAL DEFAULT 3 ntlast.4722
- -rw-rw-r-- 1 pini pini 182536 Jan 21 09:07 .libs/clptur.o
First, the size of the generated object file isn't always the same.
Second, the symbol generated for the 'ntlast' variable varies from
'ntlast.4719' to 'ntlast.4722'.
Any help appreciated.
Thanks in advance,
_g.
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