10-153r2
To: J3
From: Robert Corbett/Stan Whitlock
Subject: Interpretation Request: generic resolution with
				 banned argument combinations
Date: 2010 June 16

NUMBER: F08/0006
TITLE: generic resolution with banned argument combinations
KEYWORDS: intrinsic, generic
DEFECT TYPE: interpretation
STATUS: J3 consideration in progress

QUESTION:

The specifications of some intrinsic functions and subroutines
explicitly ban certain combinations of arguments, even though
those combinations are included in the title and the argument
portion of the specification of the function or subroutine.
Examples include CMPLX and RANDOM_SEED.  Suppose one of those
intrinsic functions or subroutines is referenced with one of
the banned combinations of arguments.

Q1. If the process of generic resolution tries to resolve the
reference against the intrinsic, does it resolve the function
or subroutine to the intrinsic or should it continue trying
to resolve the function or subroutine reference?

Q2. For example, given the function reference

      CMPLX(Z, R)

where Z is COMPLEX and R is REAL, should the processor resolve
the generic reference to the intrinsic even if it could be
resolved to a user-defined function with the same signature
later in the process of resolving the reference?

Q3. Similarly, given the subroutine call

      CALL RANDOM_SEED(GET=A, PUT=B)

should the processor skip over the intrinsic subroutine to
possibly resolve the generic reference against a user-defined
subroutine with the same signature?

ANSWER:

The definition of the interface of an intrinsic consists of its
entire description in the standard, not just the names and
keywords in the section header of its definition.  All of that
information must be used to resolve a reference to an intrinsic.

A1. No, generic resolution does not resolve to an intrinsic with
an illegal combination of arguments.  Generic resolution would
continue to search user-defined specifics of the generic if
they exist.  If no match was found, the reference is illegal.

A2. No, the given reference cannot resolve to the intrinsic CMPLX.
Generic resolution would continue searching for another match in
the generic definition if there are any.  If no match is found,
the reference is illegal.

A3. No, the processor cannot resolve the given reference to the
intrinsic RANDOM_SEED since the definition of the intrinsic
RANDOM_SEED requires exactly one or no arguments.  The processor
can use whatever means it wishes to reject interfaces that do not
match the specified reference.

EDITS to 10-007:

None.

SUBMITTED BY: Robert Corbett

HISTORY: 10-153    m192  F08/0006 submitted
         10-153r1  m192  Draft answer
         10-153r2  m192  Revised answer