To: J3                                                     J3/23-203
From: Malcolm Cohen
Subject: Consecutive operators
Date: 2023-June-14
Reference: 23-161

Paper 23-161 suggests permitting consecutive operators when the
second is + or -. The remark is made that "Users presume this is
standard-conforming based on it being allowed by both Intel and gfortran."

However, gfortran 11.3.1 produces an extension warning by default,
signalling that it is not standard-conforming. Intel likewise if
standards conformance checking is requested.

Furthermore, at least two compilers give a hard error for this.

There is no functionality - as gfortran says, "use parentheses".

It is also noted that in
   a + - b ** c
the b**c is done first by both Intel and gfortran - the unary operator
does not have higher priority than **. If written
  a + -b**c
the user could get very confused.

In the case of
    a * - b
the * has higher priority than unary minus, but would be missing its
operand!

Changing Fortran's expression rules that have withstood the test of time
(since 1956) would be a risky thing to do when there is no actual
functionality improvement.

Therefore, DATA subgroup does not intend to pursue this suggestion
at this time.

===END===