Examples taken from the Fortran 2003 standard, Section C.11.2.
They are not recognized as invalid.
* * *
INTERFACE BAD8 ! this interface is invalid !
! despite the fact that it is unambiguous !
SUBROUTINE S8A(X,Y,Z)
REAL,OPTIONAL :: X
INTEGER :: Y
REAL :: Z
END SUBROUTINE S8A
SUBROUTINE S8B(X,Z,Y)
INTEGER,OPTIONAL :: X
INTEGER :: Z
REAL :: Y
END SUBROUTINE S8B
END INTERFACE BAD8
This interface fails rule (3) because there are no required arguments that can
be distinguished from the positionally corresponding argument, but in order for
the mismatch of the optional arguments not to be relevant, the later arguments
must be specified as keyword arguments, so distinguishing by name does the
trick. This interface is nevertheless invalid so a standard-conforming Fortran
processor is not required to do such reasoning. The rules to cover all cases
are too complicated to be useful.
* * *
module x
INTERFACE BAD9 ! this interface is invalid !
! despite the fact that it is unambiguous !
SUBROUTINE S9A(X)
REAL :: X
END SUBROUTINE S9A
SUBROUTINE S9B(X)
INTERFACE
FUNCTION X(A)
REAL :: X,A
END FUNCTION X
END INTERFACE
END SUBROUTINE S9B
SUBROUTINE S9C(X)
INTERFACE
FUNCTION X(A)
REAL :: X
INTEGER :: A
END FUNCTION X
END INTERFACE
END SUBROUTINE S9C
END INTERFACE BAD9
end module x
The real data objects that would be valid arguments for S9A are entirely
disjoint from procedures that are valid arguments to S9B and S9C, and the
procedures that valid arguments for S9B are disjoint from the procedures that
are valid arguments to S9C because the former are required to accept real
arguments and the latter integer arguments. Again, this interface is invalid,
so a standard-conforming Fortran processor need not examine such properties
when deciding whether a generic collection is valid. Again, the rules to cover
all cases are too complicated to be useful.
--
Summary: Ambigous interfaces not detected
Product: gcc
Version: 4.3.0
Status: UNCONFIRMED
Keywords: accepts-invalid
Severity: normal
Priority: P3
Component: fortran
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: burnus at gcc dot gnu dot org
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30068
