[PATCH] Test that errno is set to 0 at program startup

[Maciej W. Rozycki]

On Wed, 11 Sep 2024, Andreas Schwab wrote:

> > +static int
> > +do_test (void)
> > +{
> > +  TEST_COMPARE (errno, 0);
> > +  TEST_COMPARE (get_ctor_errno (), 0);
> > +
> > +  return 0;
> > +}
> > +
> > +#include <support/test-driver.c>
> 
> That only tests that the test driver does not modify errno, which is
> uninteresting.

 Good point.  The test is so simple that I think it does not need to use 
the driver as there's hardly if anything that could hang here so that it 
would require the driver's intervention (and if it did hang, so could the 
test driver anyway).

 Alternatively with some macro trickery we could arrange for test driver's 
`main' to be called second from test's local `main', so that things like 
TEST_COMPARE work as expected (and `do_test' only checks copies of `errno' 
values recorded previously).

  Maciej