https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80975
--- Comment #2 from Thomas Koenig <tkoenig at gcc dot gnu.org> ---
Restricted to the library version, the inline
version is OK:
ig25@linux-d6cw:~/Krempel/MMZero> cat t1.f90
program bogus_matmul
implicit none
real :: M(3,0), v(0), w(3)
w = 7
w = matmul(M,v)
print *,w
if( any(w .ne. 0) ) then
call exit(1)
end if
end program bogus_matmul
ig25@linux-d6cw:~/Krempel/MMZero> gfortran t1.f90 && ./a.out
7.00000000 7.00000000 7.00000000
ig25@linux-d6cw:~/Krempel/MMZero> gfortran -O t1.f90 && ./a.out
0.00000000 0.00000000 0.00000000
ig25@linux-d6cw:~/Krempel/MMZero>
