[Octave-bug-tracker] [bug #32120] complex times complex failure

[Michael C. Grant]

Follow-up Comment #15, bug #32120 (project octave):

I have to admit I am stumped. Looking at config.log, I see signs that
configure is performing the *right* tests to see what to do. Here is the test
that it runs:

       program main
 
       double complex zdotu,a(1),b(1),w
       external zdotu
       a(1) = dcmplx(1d0,1d0)
       b(1) = dcmplx(1d0,2d0)
       w = zdotu(1,a,1,b,1)
       if (w .ne. a(1)*b(1)) stop 1
 
       end

This program *fails* when compiled with "gfortran -framework vecLib", but
succeeds when compiled with "gfortran -ff2c -framework vecLib". Just to make
sure that this test just "got lucky" because it use n=1, I created this:

       program main
 
       double complex zdotu,a(3),b(3),w
       external zdotu
       a(1) = dcmplx(1d0,1d0)
       a(2) = dcmplx(2d0,1d0)
       a(3) = dcmplx(3d0,1d0)
       b(1) = dcmplx(4d0,1d0)
       b(2) = dcmplx(5d0,1d0)
       b(3) = dcmplx(6d0,1d0)
       w = zdotu(3,a,1,b,1)
       write(*,*) a(1), b(1), w
 
       end

Sure enough, this test passes with -ff2c, and fails without it. Then I tried
this:

       program main
 
       double complex a(3),b(3),w
       external xzdotu
       a(1) = dcmplx(1d0,1d0)
       a(2) = dcmplx(2d0,1d0)
       a(3) = dcmplx(3d0,1d0)
       b(1) = dcmplx(4d0,1d0)
       b(2) = dcmplx(5d0,1d0)
       b(3) = dcmplx(6d0,1d0)
       call xzdotu(3,a,1,b,1,w)
       write(*,*) a(1), b(1), w
 
       end

And I compiled this with the *exact* code used in liboctave/cruft/blas-xtra.
And again, with the -ff2c flag, it works. And this is exactly how it is
compiled in Octave:

libtool: compile:  /usr/local/bin/gfortran -ff2c -O -c blas-xtra/xzdotu.f 
-fno-common -o blas-xtra/.libs/libcruft_la-xzdotu.o

And yet, I verified, by inserting WRITE statements in xzdotu.f, that it *is*
the call to zdotu that is failing within Octave. 

The wrapper is working in isolation, when compiled using the same flags Octave
uses, but it's not working within Octave itself. I don't get it.

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