To: J3                                                     J3/26-173r1
From: /HPC
Subject: Mark C_*_COMPLEX as obsolescent
Date: 2026-June-15

References: 26-007r1 26-172 25-205r1

In 26-007r1, the Editor identified unresolved technical issue (UTI) 003
"Redundant synonyms are unnecessary and unhelpful." In paper 26-172, the
HPC subgroup recommended (in agreement with the Editor) that the new
named constants of the form C_*_COMPLEX added by paper 25-205r1 be
removed. This paper proposes applying the same reasoning consistently to
existing C_*_COMPLEX named constants.

========

01. Background

In 26-007r1, the Editor introduced UTI 003:

      Redundant synonyms are unnecessary and unhelpful.

      Adding all those *_COMPLEX named constants just confuses people
      who haven't completely understood that type complex kind numbers
      are by definition identical to the real kind numbers for their
      parts. It bloats the language, the module, and the user programs
      that we thereby encourage to use these names. It's too late to get
      rid of the old ones, but we should not continue to add more
      useless and unnecessarily verbose names.

In 26-172, the HPC subgroup recommended reverting the addition of
*_COMPLEX named constants. Here, the subgroup recommends going further
and marking the other named constants as obsolescent, so as to actively
discourage new programs from using them.

========

Edits:

[xv] Add to introduction, under Intrinsic Modules bullet:

      The redundant named constants C_FLOAT_COMPLEX, C_DOUBLE_COMPLEX,
      C_LONG_DOUBLE_COMPLEX are now considered to be obsolescent.

----

[604:14-15] Add footnotes to C_FLOAT_COMPLEX, C_DOUBLE_COMPLEX, and
C_LONG_DOUBLE_COMPLEX which state, respectively:

      The C_FLOAT_COMPLEX named constant is obsolescent.

      The C_DOUBLE_COMPLEX named constant is obsolescent.

      The C_LONG_DOUBLE_COMPLEX named constant is obsolescent.

----

[613:table 19.2] Modify the first three rows of the COMPLEX section of
the table to read:

+---------+-------------------------------------------+----------------------+
|         | C_FLOAT (or C_FLOAT_COMPLEX*)             | float _Complex       |
| COMPLEX | C_DOUBLE (or C_DOUBLE_COMPLEX*)           | double _Complex      |
|         | C_LONG_DOUBLE (or C_LONG_DOUBLE_COMPLEX*) | long double _Complex |
+---------+-------------------------------------------+----------------------+

where the asterisks are footnotemarks with the same obsolescence text as
the edit on page 604.

----

[667:32] Add a new item to the list of obsolescent features:

(XX) C_FLOAT_COMPLEX, C_DOUBLE_COMPLEX, and C_LONG_DOUBLE_COMPLEX named
constants - see B.3.15+.

[670:4] Add a new subclause and paragraph:

B.3.15+  C_FLOAT_COMPLEX, C_DOUBLE_COMPLEX, and C_LONG_DOUBLE_COMPLEX
named constants

C_FLOAT_COMPLEX, C_DOUBLE_COMPLEX, and C_LONG_DOUBLE_COMPLEX named
constants are redundant to, and have the same values as, the named
constants C_FLOAT, C_DOUBLE, and C_LONG_DOUBLE, respectively. Use the
latter constants instead of the former.

==END==