Rule 10.3, conversion from complex types to real floating types

[misra-c]

When a value of complex floating type is converted to a real floating type, the imaginary part is discarded (C99 6.3.17(2)) and the real part is converted according to the normal C conversion rules. The normal MISRA C:2012 guidelines apply to the conversion on the real part.

Code:

d = fc;  // permitted float -> double conversion
  f = fc;  // permitted no conversion required as float to float

However the following would violate rule 10.3

Code:

double _Complex dc;
  f = dc;  // violates rule 10.3 since real part undergoes narrowing conversion.

When a value of real floating type is converted to a complex floating type, the imaginary part is given the value of 0 (C99 6.3.17(1)) and the real part is converted according to the normal C conversion rules. The normal MISRA C:2012 guidelines apply to the conversion on the real part.

Code:

fc = d;  // violates rule 10.3 since real part undergoes narrowing conversion.
   fc = f;  // permitted no conversion required as float to float

More discussion on MISRA C:2012 handling of complex types can be found at http://www.misra.org.uk/forum/viewtopic.php?t=1273