Issue 0206: Default argument conversion of float _Complex

This issue has been automatically converted from the original issue lists and some formatting may not have been preserved.

Authors: Clive Feather (UK)
Date: 1999-09-13
Reference document: ISO/IEC WG14 N892
Submitted against: C99
Status: Closed
Converted from: summary-c99.htm, dr_206.htm

Summary

For consistency with real floating types, the type float _Complex should be promoted by the default argument promotions to double _Complex.

Suggested Technical Corrigendum

Change 6.5.2.2p6 in part, from:

and arguments that have type float are promoted to double.

to:

and arguments that have a corresponding real type of float are promoted, without change of type domain, to a type whose corresponding real type is double.

Comment from WG14 on 2001-09-18:

Committee Response

This was intentional because real float promotion to double is in Standard C purely for compatibility with K&R. Since complex is new, that compatibility is not an issue, and having it behave like real float would introduce undesired overhead (and be less like Fortran).

The following words were added the Rationale.

float _Complex is a new type with C99. It has no need to preserve promotions needed by pre-ANSI-C. It does not break existing code.