CODEWITHSUNDEEP
cc-preprocessorkeil
Mohammad Kholghi
Mohammad Kholghi

Reputation: 783

Can't use "__has_include" preprocessor in Keil IDE

I'm using Keil to code for STM32 microcontrollers. In main.h file, I use this code:

#if defined __has_include //Keil recognizes this preprocessor. If it was unavailable, Keil would have marked it as gray
#if __has_include("Debugg.h")
    #include "Debugg.h"
#endif
#endif

This, checks if the Debugg.h file exists. Let's imagine I have a #define in Debugg.h file:

#define    DEBUGGING    1

Now, I expect that in main.h, the DEBUGGING is defined. Again main.h:

#if defined __has_include //Keil recognizes this preprocessor. If it was unavailable, Keil would have marked it as gray
#if __has_include("Debugg.h")
    #include "Debugg.h"
#endif
#endif

#ifdef  DEBUGGING
#define MAIN_DEBUG                  1 //This line runs
#else
#define MAIN_DEBUG                  0 //Keil IDE mark this line as gray, meaning "unavailable code"
#endif

But, whenever I try to print MAIN_DEBUG or use it, it is 0!

NOTE: It seems that Keil IDE recognizes the __has_include preprocessor, but the compiler DOES NOT; because when I comment out these lines:

//#if defined __has_include
#if __has_include("Debugg.h")
    #include "Debugg.h"
#endif
//#endif

I get these errors:

compiling main.c...
..\Library\main.h(5): error:  #59: function call is not allowed in a constant expression
  #if __has_include("Debugg.h")
..\Library\main.h(5): error:  #31: expression must have integral type
  #if __has_include("Debugg.h")
..\Library\main.c: 0 warnings, 2 errors

I also use the default ARM compiler version 5. Any suggestions?

Thanks.

Upvotes: 0

Views: 621

Answers (1)

KamilCuk
KamilCuk

Reputation: 141523

Any suggestions?

Do not use non-portable extensions like __has_include. Build systems are used to detect information about environment, like available headers.

For example, CMake build system has check_include_file that you can check if an include file exists. Then if the include file Debugg.h (why upper+lower case mix?) exists, then add a macro HAS_DEBUGG_H to compilation and if that macro is defined, then include the header.

a libX.c, a libX.h and libX_conf.h file. the checking for Debugg.h is in config file. If it was available, it checks for the prints of a specific thread. If not, debugging is deactivated

That should be done with a macro, not with "detecting header file". There should be a macro, called like LIBX_DEBUG_ENABLE and if defined, libX should output debugging information. I.e. it is a user configuration setting done with a macro, not with deleting a file.

Upvotes: 1

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