J3 01-182
To:      J3
From:    /interop
Date:    21 March 2001
Subject: Unresolved issue 243

Unresolved issue 243 (p. 395) asks about the interaction between C
and Fortran exception handling.

There are really two issues discussed in issue 243.

Issue #1: What is the interaction between C and Fortran IEEE
exception flags.

Issue #2: What is the interaction between C signal handlers
and Fortran.

Issue #1 was addressed in an earlier paper that resulted
in edits to 15 (see, for example, note 15.5).

Issue #2 has not been addressed. C contains a function called
signal which takes as an argument a pointer to a function.
The function pointed to is called a signal handler. When
certain asynchronous events (called signals) occur, the signal
handler is invoked.

There are numerous restrictions on the C environment and
on the actions that a signal handler may take. These restrictions
make it unreasonable to allow Fortran procedures to invoke
signal handlers.

Fortunately, Fortran procedures do not interoperate with C
function pointers, so there is no way to establish a Fortran
procedure as a signal handler. Thus no edits to disallow this
case are required.

There might also be a problem if a signal was raised while
executing a Fortran subprogram, and a C signal handler was
invoked. Subgroup believes that such issues are outside of
the scope of this standard.

Edits:

Delete unresolved issue
[393:1-6] delete