Lcov coverage of gfortran with the testsuite

[Thomas Koenig]

Hello world,

I just looked at

https://gcc.gnu.org/ml/gcc/2017-04/msg00136.html

where Martin Liska shared some results about testsuite
coverage of gcc.  Quite interesting.  Some remarks:

We seem to have quite good coverage overall.

Many of the lines which are never reached are stuff ike internal errors
or gcc_unreachable, which is sort of the point.

Other areas which are not covered deal with specific features, or, more
common, error conditions.  It might be a good idea to write test cases
that specifically test these code paths.  So, if anybody has a few
minutes...

Regards

	Thomas