diff options
Diffstat (limited to 'lib/verify.h')
-rw-r--r-- | lib/verify.h | 47 |
1 files changed, 28 insertions, 19 deletions
diff --git a/lib/verify.h b/lib/verify.h index fbabd82c0..328980fa3 100644 --- a/lib/verify.h +++ b/lib/verify.h @@ -23,24 +23,33 @@ /* Each of these macros verifies that its argument R is a nonzero constant expression. To be portable, R's type must be integer (or - boolean). Unlike assert, there is no run-time overhead. */ - -/* A type that is valid if and only if R is a nonzero constant expression. - The symbols verify_type__ and verify_error_if_negative_size__ are - private to this header file. */ - -# define verify_type__(R) \ - struct { unsigned int verify_error_if_negative_size__ : (R) ? 1 : -1; } - -/* Verify requirement R at compile-time, as a declaration. */ - -# define verify(R) \ - extern int (* verify_function__ (void)) [sizeof (verify_type__ (R))] - -/* Verify requirement R at compile-time, as an expression. - This macro can be used in some contexts where verify cannot, and vice versa. - Return void. */ - -# define verify_expr(R) ((void) ((verify_type__ (R) *) 0)) + boolean). Unlike assert, there is no run-time overhead. + + There are two macros, since no single macro can be used in all + contexts in C. verify_true (R) is for scalar contexts, where it + may be cast to void if need be. verify (R) is for declaration + contexts, e.g., the top level. + + The symbols verify_error_if_negative_size__ and verify_function__ + are private to this header. */ + +/* Verify requirement R at compile-time, as an integer constant expression. + Return true. */ + +# ifdef __cplusplus +template <int w> + struct verify_type__ { unsigned int verify_error_if_negative_size__: w; }; +# define verify_true(R) \ + (!!sizeof (verify_type__<(R) ? 1 : -1>)) +# else +# define verify_true(R) \ + (!!sizeof \ + (struct { unsigned int verify_error_if_negative_size__: (R) ? 1 : -1; })) +# endif + +/* Verify requirement R at compile-time, as a declaration without a + trailing ';'. */ + +# define verify(R) extern int (* verify_function__ (void)) [verify_true (R)] #endif |