Diagnostic 8000: There is a conflict between local interface block and external interface block.

Published: 12/23/2009, Last Updated: 12/23/2009

The Intel Fortran compiler error message:

error #8000: There is a conflict between local interface block and external interface block.

is issued under the following conditions:

  • A source file contains an INTERFACE block for an external Fortran procedure
  • The interface does not match the declared interface of the actual external procedure
  • The application is compiled with the "check routine interfaces" diagnostic option (/warn:interface on Windows*, -warn interface on Linux* or Mac OS* X)
An example source that would give this error is:

program test

interface
subroutine sub(x)
integer x
end subroutine sub
end interface

call sub(3)

end

subroutine sub(x)
real x ! Does not match integer
print *, x
end
In this case, as in many others, error 8000 would be accompanied by error 6633 about the type mismatch on the call.

The recommended solution is to put the called procedure in a module (and then USE the module), or to make it a contained procedure - either one will define an explicit interface without the need for a separate, error-prone INTERFACE block.
The following article describes a compiler defect that can cause this diagnostic to be issued incorrectly:

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