[gmx-users] Regarding the broken compiler gcc 4.1.x

[rashmi_chem at iitb.ac.in]

Dear gmxusers,

The warning on the GROMACS download page says :

WARNING: do not use the gcc 4.1.x set of compilers. They are broken. These
compilers come with recent Linux distrubutions like Fedora 5/6 etc.


So I installed CentOS 4.3 with gcc 3.4.5 and Fedora 10 with gcc 4.3.2 on
two different machines with same configuration( quad core dual xeon
machine clock 2 GHz). In both the machines Gromacs-4.0.4 was installed and
tetsed using corresponding gmxtest set. Many tests failed as following:

All 16 simple tests PASSED
FAILED. Check files in field
FAILED. Check files in tip4p
FAILED. Check files in tip4pflex
FAILED. Check files in water
4 out of 14 complex tests FAILED
FAILED. Check files in kernel020
FAILED. Check files in kernel120
FAILED. Check files in kernel121
FAILED. Check files in kernel122
FAILED. Check files in kernel123
FAILED. Check files in kernel124
FAILED. Check files in kernel220
FAILED. Check files in kernel221
FAILED. Check files in kernel222
FAILED. Check files in kernel223
FAILED. Check files in kernel224
FAILED. Check files in kernel320
FAILED. Check files in kernel321
FAILED. Check files in kernel322
FAILED. Check files in kernel323
FAILED. Check files in kernel324
16 out of 63 kernel tests FAILED
 pdb2gmx tests PASSED


But when the same tests were performed on CentOS 5.0 with "gcc 4.1.2" (so
called "broken compiler"), all tests passed except one.

All 16 simple tests PASSED
FAILED. Check files in dec+water
1 out of 14 complex tests FAILED
All 63 kernel tests PASSED
All 45 pdb2gmx tests PASSED


These results are quite confusing and puts a question about the validity
of the gmxtest set. The reference files in gmxtest-4.0.4 set (new) are
similar to gmxtest-3.3.2 set (old) and have not been updated.
If so how can one perform these tests on gromacs-4.0.4 and compare the
newly  generated files with the reference files?


If gcc 4.1.x is supposed to be "broken" and should not be used for
installing Gromacs, then why are gmxtests performing better in this case?


Are gcc 4.1.x series of compilers still broken? because the message on
gromacs download page is quite old.

Thanxs in advance.

regards
Rashmi