diff options
Diffstat (limited to 'math/math.h')
| -rw-r--r-- | math/math.h | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/math/math.h b/math/math.h index faa2481731..5ad8156555 100644 --- a/math/math.h +++ b/math/math.h @@ -448,6 +448,15 @@ enum /* Return nonzero value if sign of X is negative. */ # if __GNUC_PREREQ (6,0) # define signbit(x) __builtin_signbit (x) +# elif defined __cplusplus + /* In C++ mode, __MATH_TG cannot be used, because it relies on + __builtin_types_compatible_p, which is a C-only builtin. + The check for __cplusplus allows the use of the builtin instead of + __MATH_TG. This is provided for libstdc++, only to let its configure + test work. No further use of this definition of signbit is expected + in C++ mode, since libstdc++ provides its own version of signbit + in cmath (which undefines signbit). */ +# define signbit(x) __builtin_signbitl (x) # elif __GNUC_PREREQ (4,0) # define signbit(x) __MATH_TG ((x), __builtin_signbit, (x)) # else |