LANG.PREPROC.PASTEHASH : ## Follows # Operator

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An application of the # operator in a macro definition is immediately followed by an application of the ## operator.

The # and ## operators will also trigger Macro Uses # Operator and Macro Uses ## Operator warnings, respectively (if these classes are enabled).

Class Name

## Follows # Operator

Significance

style

Mnemonic

LANG.PREPROC.PASTEHASH

Categories

MisraC2023	MisraC2023:20.11	A macro parameter immediately following a # operator shall not immediately be followed by a ## operator
Misra2012	Misra2012:20.11	A macro parameter immediately following a # operator shall not immediately be followed by a ## operator
AUTOSARC++14	AUTOSARC++14:A16-0-1	The pre-processor shall only be used for unconditional and conditional file inclusion and include guards, and using the following directives: (1) #ifndef, (2) #ifdef, (3) #if, (4) #if defined, (5) #elif, (6) #else, (7) #define, (8) #endif, (9) #include.
	AUTOSARC++14:M16-3-1	There shall be at most one occurrence of the # or ## operators in a single macro definition.
MisraC++2023	MisraC++2023:19.3.2	A macro parameter immediately following a # operator shall not immediately be followed by a ## operator
CWE	CWE:710	Improper Adherence to Coding Standards
CERT-C	CERT-C:PRE30-C	Do not create a universal character name through concatenation
POW10	POW10:8	Limit the use of the preprocessor to file inclusion and simple macros.
JPL	JPL:20	Make only very limited use of the C pre-processor.

Availability

Available for C and C++.

Enabling

Checks for this warning class are disabled by default. To enable them, add the following WARNING_FILTER rule to the project configuration file.

WARNING_FILTER += allow class="## Follows # Operator"

#define A( x, y ) #x ## y  /* '## Follows # Operator' warning issued here.
                            * (also 'Macro Uses # Operator' and
                            * 'Macro Uses ## Operator' warnings, when enabled)
                            */


#define B( x, y ) #x x+y ## y         /* ## does not directly follow #.
                                       * ('Macro Uses # Operator' and
                                       * 'Macro Uses ## Operator' warnings only, when enabled)
                                       */

The following configuration file parameters affect checks for this warning class.

LANG.PREPROC.PASTEHASH : ## Follows # Operator

Summary

Properties

Example

Relevant Configuration File Parameters