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| -rw-r--r-- | ChangeLog | 6 | ||||
| -rw-r--r-- | math/math.h | 9 |
2 files changed, 15 insertions, 0 deletions
diff --git a/ChangeLog b/ChangeLog index 64f5ca7ff3..e3f0faa3da 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,9 @@ +2017-10-17 Romain Naour <romain.naour@gmail.com> (tiny change) + + [BZ #22296] + * math/math.h: Let signbit use the builtin in C++ mode with gcc + < 6.x + 2017-10-17 Adhemerval Zanella <adhemerval.zanella@linaro.org> * scripts/build-many-glibcs.py (Context.add_all_configs): 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 |