是否将同一实体传递给具有不同意图未定义行为的参数? [英] Is passing the same entity to arguments with different intent undefined behavior?

问题描述

module foo
contains
   subroutine bar()
      integer :: i(3)

      i(1) = 1
      i(2) = 2
      i(3) = 3
      call baz(i, i)
   end subroutine

   subroutine baz(a,b)
      integer, intent(in) :: a(:)
      integer, intent(inout) :: b(:)

      b(2) = 5
      print *, a
      print *, b
   end subroutine

end module
program xx
   use foo
   call bar()
end program

在这段代码中，我将相同的数组i传递给baz，将其绑定到具有不同意图的参数.当然，当我打印a时，它会改变.这是未定义的行为，还是符合规范?

In this code, I am passing the same array i to baz, binding it to arguments having different intent. Of course, when I print a, it changes. Is this undefined behavior, or it is according to specification ?

请注意，我完全希望这会发生.我对这种行为并不感到困惑，我只想了解它是否有效.

Note that I fully expect this to happen. I am not puzzled by the behavior, I just want to understand if it's valid or not.

推荐答案

这是未定义的行为. Fortran通常禁止参数别名(即，多个参数指向相同的实际数据)，除非这些参数具有POINTER或TARGET属性.

It is undefined behavior. Fortran generally prohibits argument aliasing (i.e. several arguments pointing to the same actual data), unless the arguments have the POINTER or TARGET attributes.

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