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Re: [Patch, fortran] PR30236 - alternate-return subroutine in generic interface causes ice/segfault

Paul Thomas wrote:
A wrinkle here is whether or not this is valid fortran. Most compilers that I have access to seem to quietly compile this..... well, noisily, actually, since they complain about the obsolescent feature, but compile it they do. However, in the thread on comp.lang.fortran;
Michael Metcalf offers the advice that this is invalid because the alternate returns are not data object arguments and should not be counted.

Brooks, as reporter and correspondent on the fortran thread, what do you think? Is this a -std=gnu or unconditionally an error?

There's a tiny-but-significant difference between this testcase and what I described on the comp.lang.fortran thread. This case is unambiguously legal (unless I'm missing something like "alternate returns are not allowed in generic interfaces at all", which Mike's answer on to my question on c.l.f. implies that I'm not).

Specifically, in the testcase here, the two specific subroutines have argument lists like so:

+   subroutine with(i,*)
+   subroutine without()

These are distinguishable even if the alternate-return dummy argument is ignored. The c.l.f. question applied to the more subtle case where the second one has an argument list of "(i)", so the alternate-return is the _only_ difference; that's why that case was arguably illegal.

So, yeah, the code in the testcase in your patch is completely valid.

- Brooks

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