MISRA.DEFINE.SHARP.ORDER.2012

MISRA C 2012 Rule 20.11: A macro parameter immediately following a # operator shall not immediately be followed by a ## operator

A macro parameter immediately following a '#' operator shall not immediately be followed by a '##' operator.

C90 [Unspecified 12], C99 [Unspecified 25]

Category: Required

Analysis: Decidable, Single Translation Unit

Applies to: C90, C99

Rationale

The order of evaluation associated with multiple #, multiple ## or a mix of # and ## preprocessor operators is unspecified. The use of # and ## is discouraged by Rule 20.10. In particular, the result of a # operator is a string literal and it is extremely unlikely that pasting this to any other preprocessing token will result in a valid token.

Example

#define A( x )         #x          /* Compliant     */ 
#define B( x, y )      x ## y      /* Compliant     */ 
#define C( x, y )      #x ## y     /* Non-compliant */

See also

Rule 20.10