Compiler should raise an error for certain combinations of #define

Question

In a current project, I'm experimenting around a lot to see the performance influence of different solutions. Since I like to keep all the code, I have a lot of #ifdef directives, which make it easy for me to switch on and off some optimizations. However, some combinations of defines are not covered. I'd like to see a compiler error if this happens, i.e.:

#define A
#define B

#ifdef A
#ifdef B
//invalid combination of defines. Compiler should raise an error.
#endif
#endif

#ifdef A
//do something
#endif
#ifdef B
//do something else
#endif

Is that possible?

score 8 · Accepted Answer · edited May 23 '17 at 11:59

8

Yes. Just use the error directive (#error).

#ifdef A
#ifdef B
#error "invalid combination of defines."
#endif
#endif

edited May 23 '17 at 11:59

Community

1
1

answered Jul 08 '12 at 10:15

kennytm

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Edit: Sorry, seems you edited your post while I figured that out. – mort Jul 08 '12 at 10:20

score 2 · Answer 2 · answered Jul 08 '12 at 10:15

2

#ifdef A
#ifdef B
//invalid combination of defines. Compiler should raise an error.
#error Invalid combination
#endif
#endif

answered Jul 08 '12 at 10:15

Daniel Fischer

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score 2 · Answer 3 · answered Jul 08 '12 at 10:18

2

Use the error Preprocessor directive:

#error "Invalid combination"

answered Jul 08 '12 at 10:18

score 2 · Answer 4 · answered Jul 08 '12 at 10:19

2

#if defined(A) && defined(B)
#error invalid combination of defines
#endif

answered Jul 08 '12 at 10:19

ouah

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Thanks for hte hint with defined! – mort Jul 08 '12 at 10:21

Compiler should raise an error for certain combinations of #define

4 Answers4