[Bug testsuite/32956] Compiling equiv_7_db.f90 gives an error with -fdefault-integer-8

[dominiq at lps dot ens dot fr]

------- Comment #3 from dominiq at lps dot ens dot fr  2007-08-02 16:37 -------
Subject: Re:  Compiling equiv_7_db.f90 gives an error
 with -fdefault-integer-8

> These two examples are the poster child for
> 1) Why -fdefault-integer-8 is a bad option and should only be
>    used by people who are prepared to have broken results.
> 2) Why EQUIVALENCE is a horribly abused construct.

This reminds me a very old joke I have read about a famous computer company:

... is like death or taxes, you don't like them, but you cannot escape them!

More seriously I find the -fdefault-integer-8 option of rather dubious
interest, at least as a physicist. However -fdefault-real-8 is one of
the feature my colleagues keep asking for. It is very handy to test the
benefits
of doubles in term of accuracy and their drawbacks in term of CPU and memory.
Indeed if you find a critical application relying on these options, you are
right
to be worried.

> In fact, from equiv_7.f90, this is invalid

Yes, g95 emits a lot of warnings about nonstandard equivalences in that case
and gfortran detects the problem.  However this construct is the only way I
know
in f77 to access memory in different ways (as done in the two cases to cope
with endnian madness) so you are likely to find it in many old libraries.

What is more interesting is why the problem is not detected in the second case
and why the executable hangs?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32956